Biological Molecules Flashcards
What is a molecule
A molecule is made up of two or more of the same or different elements chemically bonded together
What are biological molecules
Compounds that living organisms are made up of
Examples of Biological molecules
Proteins
Carbohydrates
Lipids
Nucleic acids
Biological molecules are… (1)
Large and complex macromolecules made up of many atoms bonded together
Many but not all are polymers
Biological molecules are… (2)
Organic- carbon forms main structural part of each biological molecule
- all contain C-C or C-H bonds
What is the opposite of organic and why
Inorganic- do not contain C-C or C-H bonds
Examples of inorganic biological molecules
C02
CaCO3
Biological molecules are… (3)
Made up of maximum of 6 elements
- carbon
-hydrogen
-nitrogen - oxygen
-phosphorus - sulphur
What elements can be found in the macromolecule carbohydrate
Carbon
Hydrogen
Oxygen
What elements can be found in the macromolecule lipids
Carbon
Hydrogen
Oxygen
What elements can be found in the macromolecule proteins
Carbon
Hydrogen
Oxygen
Nitrogen
Sulphur
What elements can be found in the macromolecule nucleic acids
Carbon
Hydrogen
Oxygen
Nitrogen
Phosphorus
What are most of the atoms in biological molecules and how are they bonded together?
Most atoms= non-metals, are held together by covalent bonds through sharing electrons
Define monomer
Small units which are linked together to form larger molecules e g. monosaccharides
Define polymer
Long chain molecules made up of monomers which are linked together in a repeating pattern
Give examples of polymers
Proteins
Carbohydrates
Nucleic acids
Give example of what’s not a polymer
Lipids
Why are polymers great biological molecules
Can easily be broken down into monomers when necessary and join back together to make polymers
Explain how monomers are turned into polymers
Monomers are joined together in a condensation reaction where water is released to make polymers
What is dehydration synthesis also known as
Condensation reaction
What is also known as a condensation reaction
Dehydration synthesis
How are polymers broken down to make monomers
Polymers are broken down to make monomers by addition of water in Hydrolysis reaction
What is an ion
Atom that has lost or gained electron
Benefits of inorganic ions
Essential for functioning of living organisms e.g. communication between cells and controlling the movement of water in and out of cells and tissues
What charge do metals have and what are the known as?
- Positive
- known as cations
Why are metals positively charged
Because they lose electrons
What charge do non metals have and what are they known as?
-negative
-anions
Why are non metals negatively charged
Because they gain electrons
Name all cations that are used within living organisms
Calcium, sodium, potassium, hydrogen, ammonium
The cation calcium is useful in the human body because?
Ca2+ :
-transmission of nerve impulses across synapses
-Muscle contraction
-Cofactor in blood clotting
-Bone and tooth enamel structure (Calcium Phosphate)
The cation Sodium is useful in the human body because?
Na+ =
-nerve impulse transmission
- reabsorption of water in kidneys
- involved in co-transport
The cation potassium is useful in the human body because?
K+ =
-nerve impulse transmission
-water reabsorption in the nephron
- control of stomatal opening
The cation hydrogen is useful for the human body because?
H+ =
-catalysis of reactions
-ph determination
-involved in chemiosmosis
-formation of H bonds
-ATP formation
-control of blood pH + CO2 transport
The cation ammonium is useful for the human body because?
NH4 + =
- production of nitrate ions by bacteria from ammonium ions
- involved in nitrogen cycle
-involved in the deamination of proteins
The anion nitrate is useful for the human body and plants because?
NO3 minus = nitrogen supply to plants for amino acids and protein formations
The anion hydrogen carbonate is useful for the human body because?
HCO3 minus =
-maintains blood pH
-involved in CO2 transport in blood
The anion chloride is useful for the human body because?
Cl- =
-to balance positive charge of sodium and potassium ions in cells by providing negative charge
-maintains the pH balance in RBCs during CO2 transport
The anion phosphate is useful for the human body because?
PO4 3- =
-cell membrane formations from phospholipids
-Nucleic acids and atp formations
-bone formation
-part of calcium phosphate in bones + tooth structure
The anion hydroxide is useful for the human body because?
OH- =
-catalysis of reactions
-ph determination
-involved in bonding between biochemical molecules
What is an ionic compound
- anion + cation are joined together= an ionic compound
What can ions join to make
Many cations + anions can join together to make a giant ionic lattice
What is an example of a biologically important ionic compound
Sodium chloride (NaCl)
Give 3 properties of ionic compounds
-conducts electricity when molten/in aqueous solution
- strong electrostatic force of attraction
- high melting/boiling point
What is a monomer
Small units which can be linked together to form larger molecules. e.g. monosaccharides
What is a polymer
long chain molecules -made up of monomers bonded together in a repeating pattern
What is the name of the reaction in which monomers are joined together
Dehydration synthesis or Condensation reaction- water is released
What is the name of the type of reaction in which monomers are separated apart
Hydrolysis and it requires water
Human pancreatic lipase breaks the bonds between fatty acids and glycerol. What is the name given to this reaction
Hydrolysis
Plant seedlings were grown in a solution that contained various dissolved ions.
The function of the ion is that it supplies elements that form part of the structure of amino acids and nucleotides, what is the name of this ion
Nitrates
N03, minus
Plant seedlings were grown in a solution that contained various dissolved ions. The function of the ion is that it forms part of the structure of DNA and phospholipids, what is the name this ion
Phosphate
PO4, 3 minus
Why is water important
Because of its unique life-supporting properties that are caused by hydrogen bonding
Why do living organisms need water
-Aquatic organisms- obtain oxygen from water
-Maintain homeostasis when excreting- it keeps us hydrated for water we have lost
-Sweating- water loss to keep us cool in hot temperatures
- Excellent solvent- good for transport of glucose+ salt in blood+ transport other minerals in xylem and phloem cells of plants
-water provides medium for chemical reactions in cytoplasm
Draw a water molecule.
Page 10 of introduction to water booklet
Draw a dot and cross diagram of a water molecule
Page 10 of introduction to water booklet
Show the structural or displayed formula of water
Page 10 of introduction to water booklet
What is a hydrogen bond
A weak bond formed between a slightly electronegative atom and a slightly electropositive atom in different molecules
How many hydrogen bonds can each water molecule form
Each water molecule can form up to 4 hydrogen bonds
How many hydrogen bonds are there in one drop of water
6.68 * 10 to the power of 21
hydrogen bonds
What is special about hydrogen bonds
One hydrogen bond is weak but many collectively are strong
Why does water form hydrogen bonds
Water = polar molecule- there is an uneven charge distribution across molecule- one part is a little bit + and one part is a little bit -
Describe the bonding between 2 oxygen molecules
1) Oxygen atoms are same size- they have the same electronegativity so exert the same pull on the pair of electrons in covalent bond between them
-electrons stay exactly in middle between 2 oxygen atoms
- means that charge distribution across molecules is equal therefore it is non polar
Describe the bonding between Oxygen and Hydrogen atoms
-Oxygen atom-much larger than hydrogen atom
- oxygen atom has a greater electronegativity it exerts a stronger pull on the pair of electrons in the bond
-the electrons are pulled closer to the oxygen atom than the hydrogen atom
-means that there is a slightly more negative charge around the oxygen atom and slightly less around the hydrogen atom
Describe how a water molecule is formed
-water molecule has 2 O-H bonds so it has 2 slightly positive regions over the hydrogen atoms and 1 slightly negative regions over the oxygen atom
Describe the property and structure of water and how this makes it a good solvent
-Universal solvent
- polar (hydrophilic)- so charged molecules dissolve readily in it
- the slightly + charge on H will attract any - solutes
- the slightly - charge on O atom of water will attract any+ ions in solutes
Describe using structure and properties of water, how it is a good transport medium
-Polar substance- dissolve, easily transported in H20 in blood of animals + xylem of plat cells where needed in organisms
-Cohesion between H2O molecules allows it to transport dissolved solutes
- Cohesion= ‘sticking together’ by H bonds- formed between H + O atoms in different molecules
- H20 moves up xylem of plants due to transpiration- as a continuous column of water
- Adv= when H20 evaporates out of stomata in leaves - it leaves a negative pressure which pulls on the continuous column of water so it is easily transported up the stem as it is all coheased/ stuck together
- if seperate, molecules- would be much harder/ impossible for H20 molecules to move up xylem
- properties allow for efficient transport of nutrients + waste in organisms
How does water form hydrogen bonds?
- -region of O atom of one H2O molecule is attracted to the + region of the H atoms of another H20 molecule
Choose the write option:
In a water molecule,
a)all of the atoms have a slightly positive charge
b) the oxygen atom has a slightly negative charge and the hydrogen atoms have a slightly positive charge
c) the oxygen atom has a slight positive charge and the hydrogen atoms have a slightly negative charge
d) all of the atoms have a slight negative charge
B
The bond between one hydrogen atom and the oxygen atom in a water molecule is a:
a) hydrogen bond
b) ionic bond
c)covalent bond
d)James bond
In a water molecule= covalent
between water molecules= hydrogen bond
answer= c
The electrons are shared ____________ between the atoms in a water molecule.
a) equally
b) unequally
c) fairly
d) unfairly
Answer= b
unequally
A water molecule is:
a) electronegative
b) polar
c) non-polar
d) charged
b
polar
Water molecules are attracted to one another because they are:
a) fit
b) polar
c) non-polar
d) electronegative
b= Polar
Hydrogen bonds are formed between:
a) The oxygen and each hydrogen atom in a water molecule
b) 2 hydrogen atoms in a hydrogen molecule
c)between hydrogen atoms in different molecules
d) between a slightly electronegative atom in 1 molecule and a slightly electropositive atom in a different molecules
d
Practical observations made:
Water has a much higher specific heat capacity than other substances/materials e.g. oil or aluminum
How does Hydrogen bonding cause this ?
Many hydrogen bonds that link water molecules let water absorb large amount of heat without changing its chemical state e.g. liquid to gas
How does water having high specific heat capacity help organisms
-stabilizes temp in large bodies of water e.g. ponds /lakes/ oceans +helps organisms maintain homeostasis as water temperature changes over a period of time rather than rapid change
-provides good aquatic habitat e.g. pond stays at a relatively constant temperature- allows survival of organisms
How does Hydrogen bonding cause Cohesion in water molecules?
Water molecules show a strong attraction to one another, hydrogen bonds in water allow water molecules to stick together
Why is cohesion good in water molecules for us?
This property allows for efficient transport of nutrients and waste in organisms.
Water molecules formed a sphere like a thick layer of water molecules stuck to each other- useful for water striding insects that live on water as this creates a high surface tension.
Why is ice less dense than water. Use hydrogen bonding in your answer to explain this.
Configuration of hydrogen bonds in water cause it to expand when it freezes- expansion causes ice to have lower density than liquid water so it floats on top.
Why is ice being able to float on liquid water good for us?
Bodies of water freeze from the top down- acts as insulator to protect water below it from freezing this protects aquatic organisms so they can survive winter
Sugar, water, oil, salt do not dissolve / combine in the water rather separate into layers (oil+ water) precipitates (sugar +salts) at the bottom- How does hydrogen bonding cause this
To do with the polarity and hydrogen bonding ability of water molecules- makes it a universal solvent as long as the other substances are also polar
Why is that good in living organisms?
Cells are mostly made up of water- these solutions of ions + molecules allow chemical reactions to occur much more frequently- important as it allows organisms to respond to their environment
Why does a paper clip float on water using hydrogen bonding?
Surface tension of water-water molecules at surface are much more strongly attracted to each other than the air above so cling tightly onto each other on which paperclip balances
Why is high surface tension good within water molecules- how can this be beneficial to living organisms?
Water beads upon waxy surfaces+ water striding insects are able to walk and live on the surface of water
Define polar compound
When a compound has an uneven charge distribution
Define hydrogen bond
Weak bond formed between slightly electronegative atom and a slightly electropositive atom of different molecules
Define Cohesion in terms of water
water molecules sticking to each other
Define adhesion in terms of water
water molecules sticking to other surfaces
When NaCl is dissolved in water the sodium ions
a) are attracted to the oxygen atoms of water molecules
b) are attracted to the hydrogen atoms of the water molecules
c) are attracted to each other
d) do not dissociate from the sodium chloride
A
Hydrogen bonds
a) form between hydrogen atoms in different molecules
b) are strong bonds
c) hold water molecules to one another
d) hold the 2 hydrogen atoms together in a molecule of hydrogen gas
c
When a glass is filled to the brim with water, the water appears to bulge from the sides of the glass due to
a) Capillarity
b) thermal energy
c) adhesion
d) cohesion
Cohesion
When liquid water is heated most of the energy that the water initially absorbs is used to
a) raise the temperature of water
b) break the covalent bonds between the hydrogen and oxygen atoms in water
c) make the water boil
d) break the hydrogen bonds between the water molecules
D
Why is water a good solvent
Because of the polarity (uneven charge distribution) of the hydrogen bonding ability of water- oppositely charged ions are attracted to each other
What kinds of substances decides water can be involved in hydrogen bonding?
Ammonia (NH3) and Hydrogen fluoride gas (HF)
What property of water allows it to stick to a dry surface such as wooden countertop?
Adhesion- sticks to to other surfaces
How does water help cells to keep an uneven temperature despite temperature changes in the environment ?
Water has a high specific heat capacity- acts as a buffer in cells, helps maintain an even temperature and avoid sudden temp changes
- also helps to evenly disperse heat in our bodies- it can absorb a lot of heat before changing temperature
Explain why water forms large round drops as it falls from a faucet with a slow leak?
Cohesive forces allow water molecules in each drop to move as close as possible to one another, making the drop round
Water is often called the universal solvent because it dissolves most substances that are important to living things. What does this suggest about the nature of those substances?
Because those other substances are also polar e.g. Glucose and water dissolve however non-polar substances e.g. oil do not dissolve in water
Draw 3 water molecule and show the hydrogen bonding between them.
See water booklet page 17
The density of water decreases as the temperature falls below 4*c , so ice floats on the top of the pond
-Ice floats as it is less dense- water molecules are spread out and form crystal/ lattice structure
-this forms insulating layer- acts as a barrier to cold
- water below ice does not freeze- kept at higher temperature
-hence organisms do not freeze- animals/ organisms can still swim/ move allows currents/ nutrients to circulate and organisms to survive as a result
Water acts as a solvent for ions such as nitrates- why is this good for organisms that live in ponds?
Solubility- ions (polar/ charged) are attracted to other- charged ions /bind to other charged ions within water
-so fish or other organisms can uptake minerals and nutrients easily
A large quantity of energy is required to raise the temperature of water by 1 * c. Why is this good for organisms that live in large bodies of water?
Temperature stability- many stable hydrogen bonds between molecules
- requires a lot of energy to break bonds as it has a high specific heat capacity
-therefore temperature stays constant- small variation in temperature- stays cool in summer + warm in winter
-temperature does not have an affect on enzymes/ they wont denature so metabolic rates of fish/other aquatic organisms
State the name of the bond that holds water molecules together.
Hydrogen bond
DNA is one of many substances which will dissolve in water. Explain why water is a good solvent.
Because it is a polar molecule so it attracts ions from other substances to bind together.
- e.g. sodium chloride. Sodium is a cation so is attracted to the delta negative oxygen and Chlorine an anion so is attracted to the delta positive hydrogen atoms.
A student studies the pack of plant food, supplied by some cut flowers, the list of ions included hydrogen and sodium. Suggest what roles this may play in helping the cut flowers to last longer.
Hydrogen= used to regulate pH
Sodium= used to regulate water potential
Explain how properties relating to the density of water contribute to the survival of organisms. (3 marks)
During winter, large bodies of water freezes e.g. in lakes, ponds etc.
- when it freezes it becomes less dense as there is more distance between the hydrogen bonds which are in a fixed position so ice floats on the top
-this ice acts as an insulator to protect the water below it and protects aquatic organisms and helps them survive during winter and so provides habitat for species.
Outline the properties of water which make it an ideal habitat for an amphibian? ( 2 marks)
-H2O has high surface tension- water molecules are strongly attracted to one another- more so than the air above- so cling tightly onto each other creating a surface on which water striding insects can walk or live on.
Describe the formation of a hydrogen bond between 2 molecules of water and explain why water can form these bonds.
Hydrogen bonds occurs between a delta positive (hydrogen) and delta negative (oxygen) in different molecules. -Because oppositely charged atoms are attracted to each other and therefore form a weak bond- hydrogen bond.
-because of the charges water is known as a polar substance.
Why is the ability of water to act as a solvent important for the survival of organisms? ( 3 marks)
-it acts as a medium for metabolic reactions
-and allows ionic compounds to separate e.g. sodium chloride so that it can be transported around the body.
What are all carbohydrates made up of?
Carbon
Hydrogen
Oxygen
What are the 3 types of carbohydrates?
Monosaccharides
Disaccharide
Polysaccharides
What is a monosaccharide
a simple sugar e.g. glucose that constitutes the building block of a more complex form of sugar
What is a disaccharide
2 sugar molecules joined together
Define polysaccharide
Many sugar molecules joined together
What are the properties of monosaccharides
Glucose= sweet+ soluble
Fructose= quickly broken down in respiration to release energy
Galactose= classified according to the number of carbons in molecule
What are the properties of disaccharide
-two monosaccharides joined together
-less sweet than monosaccharides
-used for short term energy storage e.g. for transport for monosaccharides in plants
What are the properties of polysaccharides?
-many simple sugar molecules joined together to make complex structures
Uses:
-Long term energy storage in plants
-medium term energy storage in animals
-cellulose cell wall in plants
Name 4 carbohydrate monosaccharides
-ribose
-glucose
-fructose
-galactose
Ronaldo, greatest, footballer
Name 3 carbohydrate disaccharides
-maltose
-lactose
-sucrose
Messi lacks skills
Name 3 Carbohydrate Polysaccharides
Starch
Cellulose
Glycogen
Speed could grow
Monosaccharides like glucose are:
- soluble
-small
-quickly broken down to release energy
-molecules can join together in a number of different ways
What are monosaccharides with 3 carbons called
Triose sugar
What are monosaccharides with 5 sugars called
Pentose sugars
What are monosaccharides with 6 sugars called
Hexose sugars
Monosaccharides are classified by what
The number of carbon atoms they have
What is the general formula for a hexose monosaccharide like glucose
CNH2NON
Glucose= C6H1206
Give an example of a hexose monosaccharide
Glucose
What is a similarity between an alpha and beta glucose
They have the same molecular formula
What is an isomer
They have the same molecular formula but different structure e.g. glucose
True for false:
Most monosaccharides have a number of different isomers
True
What is the OH group called
Hydroxyl Group
The monomer glucose makes what polymer
Starch, Cellulose and Glycogen
The monomer amino acids makes what polymer
Amino acids make the polymer protein
The monomer Nucleotide makes what polymer
DNA and RNA
What is the difference between alpha and beta glucose
In alpha glucose the hydroxyl group is attached facing down and away from main structure while in the beta glucose the hydroxyl group is attached above the carbon ring and on the first carbon
How can you remember where the hydrogen and hydroxyl group is located on an alpha and on a beta glucose
Alpha= hydrogen on top
Beta= hydrogen on bottom
of carbon ring structure
What is ribose an example of
Pentose sugar which is used to make the nucleic acid RNA
What is deoxyribose an example of
a pentose sugar which is used to make nucleic acid DNA
What is the general formula of a pentose monosaccharide e.g. DNA
CN H2N 0N-1
Draw the pentose sugar Ribose
Page 5 carbohydrates booklet
Draw the pentose sugar deoxyribose
page 5 carbohydrates booklet
Why does deoxyribose not have the same general formula as ribose?
Deoxyribose has one less oxygen than ribose
-deoxyribose has a hydrogen whilst ribose has OH (hydroxyl)
Due to this, the deoxyribose is more stable than ribose sugar
Why is deoxyribose more stable than ribose sugar
Because deoxyribose has one less oxygen atom and instead has a Hydrogen instead of hydroxyl group present like in ribose
Fructose is a what sugar and why
-Hexose sugar because it has 6 carbons present in its structure
Galactose is what sugar and why
Hexose sugar because it has 6 carbons present in its structure
Disaccharides are made up of…
2 monosaccharides joined together with a glycosidic bond via a condensation reaction whereby water is released.
Polysaccharides are made up of…
multiple monosaccharides joined up together
Describe a similarity between synthesis of disaccharides and polysaccharides.
Both are formed by the creation of glycosidic bonds in a condensation reaction which releases
Describe a similarity between the breakdown of disaccharides and polysaccharides
They are broken down using enzymes by the addition of water to break the glycosidic bonds in a hydrolysis reactions
What is a condensation reaction
It is the joining up of 2 molecules together by removing water- a chemical bond is formed.
What is a hydrolysis reaction
It is the splitting apart of molecules through the addition of water, a chemical bond is broken
How do you make maltose
Glucose+ glucose= maltose + water
How do you make lactose
glucose+ galactose=lactose +water
How do you make sucrose
glucose+ fructose= sucrose+ water
How do we know the number of the carbon which is involved in the synthesis of the glycosidic bond e.g. 1-4 is between carbon 1 and carbon 4
We start counting by the first carbon after the oxygen in the carbon ring for when we are naming glycosidic bonds e.g. 1-4 glycosidic bond
What is the symbol equation of the synthesis of maltose
C6H1206+C6H1206= C12H22011+ H20
Description of the synthesis of maltose
The hydroxyl group on carbon 1 of one glucose monomer reacts with the hydroxyl group on carbon 4 of the second glucose monomer in a condensation reaction to release 1 water molecule. A 1-4 glycosidic bond is formed between them.
What is the precise name of the bond formed in a maltose disaccharide
1-4 glycosidic bond
What is the symbol equation of the synthesis of lactose
C6H12O6+C6H12O6= C12H22O11+ H20
Describe the synthesis of lactose
The hydroxyl group on carbon 1 of one glucose monomer reacts with the hydroxyl group on carbon 4 of the galactose monomer in a condensation reaction to release 1 water molecule. A 1-4 glycosidic bond is formed between them.
What is the precise name of the bond formed in a lactose disaccharide
1-4 glycosidic bond
What is the symbol equation for the synthesis of sucrose
C6H1206+C6H12O6= C12H22O11+ H20
Describe the synthesis of sucrose
The hydroxyl group on carbon 1 of one glucose monomer reacts with the hydroxyl group on carbon 2 of fructose- second monomer in a condensation reaction to release 1 water molecule. A 1-2 glycosidic bond is formed between them.
What is the precise name of the bond formed formed in a sucrose disaccharide
1-2 glycosidic bond
What is the symbol equation for the breakdown of maltose
C12H22O11+ H20= C6H12O6 + C6H12O6
What is the symbol equation for the breakdown of sucrose
C12H22O11+ H20= C6H12O6 + C6H12O6
What is the symbol equation for the breakdown of lactose
C12H22O11+ H20= C6H12O6 + C6H12O6
Describe the breakdown of maltose
The water molecule is used to hydrolyse the hydroxyl groups on the maltose disaccharide in a hydrolysis reaction whereby 2 hydroxyl groups are reformed to produce 2 glucose monomers using a water molecule. An enzyme is required to catalyze this reaction- Maltase. The 1-4 glycosidic bond is therefore broken.
Describe the breakdown of sucrose
The water molecule is used to hydrolyse the sucrose while it breaks down by the use of the enzyme sucrase in a hydrolysis reaction whereby one molecule of glucose and one molecule of fructose monomers are formed. The hydroxyl (OH) is formed by carbon 1 of one glucose molecule and Hydrogen (H) on carbon 2 of fructose molecule. the 1-2 glycosidic bond is therefore broken.
Describe the breakdown of lactose
The water molecule is used to hydrolyse the lactose disaccharide in a hydrolyses reaction whereby glucose and galactose are formed. Carbon 1 of galactose forms a hydroxyl group on top of the carbon ring and carbon 4 of the glucose molecule forms a hydrogen bond on top of the carbon ring therefore the 1-4 glycosidic bond is broken.
What enzyme is required in the hydrolyses of maltose
Maltase
What enzyme is required in the hydrolyses of sucrose
Sucrase
What enzyme is required in the hydrolyses of lactose
Lactase
State the precise name of the covalent bond that forms between the 2 glucose molecules and the name of the disaccharide that is formed
Bond = 1-4 Glycosidic bond
Disaccharide= Maltose
State 2 other structural similarities between lactose and maltose
-Both contain 6 carbons on the carbon ring- therefore are both hexose sugars
-they both have the same 1-4 glycosidic bond
State 4 differences between the maltose disaccharide and lactose disaccharide
Maltose=
-both monomers are glucose
-Alpha glucose
-Alpha glycosidic bond
-Both monomers in the same direction
Lactose=
-1 glucose monomer and 1 galactose monomer
-beta glucose
-beta glycosidic bond
-sugars are flipped and are not facing each other
Sucrase is the enzyme that breaks down sucrose. Which bond is broken by sucrase.
Alpha glycosidic
What are polysaccharides and their uses
They are made up of 1000s of monosaccharide monomers
-not classified as sugars- not sweet
-insoluble- so will have no osmotic effects
-most are energy storing molecules
-except for cellulose- a structural compound within cell wall
How does the structure of starch (amylose) relate to its function
The angle of the bond means the long chain of glucose twists in on itself to form a helix. It is further stabilized by hydrogen bonding between adjacent hydroxyl groups. This makes the molecule more compact and be able to fit more glucose in a small space and much less soluble than glucose making it an ideal structural and storage carbohydrate.
Where is starch ( amylose) found
Found in: plants as a chemical store- in cells
In amylose- starch what type of glucose monomers are joined together by a glycosidic bond
Types of glucose: Alpha glucose monomers
What types of bonding occurs in amylose starch between the alpha glucose monomers
Type of bonding: 1-4 glycosidic, hydrogen bonding
Describe how the structure of amylopectin relates to its function
- chains of glucose molecules made up of preferred respiratory substrate- means many glucose molecules are available- more free ends, so more respiration can take place +more glucose can be released in form of energy when needed. -has a branched structure which increases surface area + exposes multiple free ends of molecules- provides larger s.a. for enzymes to attach therefore can rapidly hydrolyse starch back to glucose, resulting in a rapid supply of energy
-Polysaccharides= insoluble in water so wont affect water potential and will have no osmotic effect, meaning excess water wont be moving into cells causing them to become turgid.
Where is amylopectin found
plants as a chemical energy store
What type of glucose monomers link together in amylopectin
Alpha glucose
What type of bonding takes place in amylopectin
1-4 glycosidic bonding between the monomers and 1-6 glycosidic bonding between branches
How does the structure of glycogen relate to its function
- highly branched molecule- it has more 1-6 glycosidic bonding than amylopectin – can be even more rapidly hydrolysed back to glucose- advantage speeds up process of storing + releasing glucose molecules required by the cell especially in animals as they are more mobile ad movement requires energy, glucose is needed in respiration to release that energy
- Highly Branched structure increases s.a- exposes multiple free ends of glucose molecule- provides larger surface area for enzymes to attach- therefore can be rapidly hydrolysed when excess glucose is stored, resulting in a rapid supply of energy
Insoluble in water so won’t affect water potential and will have no osmotic effect, meaning excess water won’t be moving into cells causing cell lysis.
Where is glycogen found
animals as a chemical energy storage for glucose in muscles and liver cells
What types of glucose monomers are needed in structure of glycogen
Alpha glucose
What type of bonding is formed between alpha glucose molecules in glycogen
1-4 glycosidic bonding between the monomers and 1-6 glycosidic bonding between branches
How does the structure of cellulose relate to its function
-Polymers form long straight chains of beta glucose- joined together by 1-4 glycosidic bond. -Microfibrils =strong threads made up of long cellulose chains joined together by hydrogen bonds
- provides structural supports in plants so it will hold its shape,
-Insoluble= won’t affect water potential, no osmotic effect- cell won’t become turgid
Where is cellulose found
plants as a structure to strengthen cell wall
What type of glucose monomers are needed to form cellulose
beta glucose
What type of bonding occurs in cellulose
1-4 glycosidic bonding
How many polysaccharides is starch made up of
It is made up of 2 polymers amylose (insoluble) and amylopectin (soluble)
What is starch used for and in which type of cell
Glucose is stored as starch in plants- used in respiration and is converted into energy source through hydrolysis reaction and addition of H20
What is the precise name of monomers that amylose is made up of
Alpha glucose monomers joined together by a 1-4 glycosidic bond
What shape beginning with h does amylose take
helix shape
What is it about the bonds between the alpha glucose monomers that causes it to be this shape
- angle of 1-4 glycosidic bond means long chain of glucose twists to form a helix
What 2 properties does amylose have
-compact
-insoluble
Amylopectin creates 1-6 glycosidic bonds between chains. What ‘b’ does this bond create
A branched structure
How often does the branches occur in amylopectin
1-6 branching points occur aprox once in every 25 glucose subunits
What is the name of the equivalent energy storage molecule to amylopectin that is found in animals and fungi
Glycogen
What is different about the branching in amylopectin compared to the branching in glycogen
Glycogen forms more branches than amylopectin
Glycogen forms more branches than amylopectin- what properties does this prove
-glycogen is more compact and less space is needed for it to be stored
-more branches= more free ends where glucose molecules can be added or removed
Why is it important for animals to be able to store a lot of energy in less space
It speeds up the process of storing or releasing glucose molecules required by the cell without increasing mass
What word beginning with ‘c’ describes the property that coiling and branching gives to storage polysaccharides
Compact
How and why does branching affect storage and release of glucose molecules
It means glucose can be stored +released quickly when required by cell
-glycogen+ amylopectin have a lot of branches + are compact so take up less space- ideal for storage, especially as animals are mobile +need more energy for respiration
- a plant would require less energy
What type of reaction is used to release glucose from starch or glycogen
Hydrolysis- uses water to breakdown starch in plants or glycogen in animals into glucose
What ‘e’ are these reactions catalyzed by
Enzymes
What are the monomers that join together to make cellulose
beta glucose
Why cant beta glucose join together in the same way that 2 alpha glucose monomers can
Because the hydroxyl group in carbon 1 and carbon 4 of the 2 glucose molecules are too far from each other to react
What has to happen to alternate beta glucose molecules to form the polymer cellulose
Alternate beta glucose molecules have to be turned upside down
What 2 things is a polymer made of beta glucose not able to do so what shape does it take instead
it is unable to coil or form branches so instead a straight chain molecule is formed called cellulose
What type of bond to cellulose molecules form with each other
Hydrogen bonds
What m does cellulose polymer joined together with hydrogen bonding create
microfibrils
What do microfibrils join together to form
Macrofibrils
What are 2 properties of microfibrils and macrofibrils and how does this suit them for their function of forming cell walls
-fibres are strong+ insoluble and need to make cell walls- which help the cell maintain shape+ keep rigid
Cellulose forms which essential part of our diet and why is it necessary for a healthy digestive system.
-very hard to break cellulose down into its monomers +forms the fiber or ‘roughage’- to allow movement of the bowel + is necessary for a healthy digestive system
-decreases risk of metabolic disorder
- decreases cholesterol levels
State similarities between cellulose and amylose
-form 1-4 glycosidic bonds
- both have no branches
State similarities between amylose and amylopectin
-storage of glucose
-very compact - can fit a lot of glucose molecules in a small space
-both use alpha glucose monomers
State similarities between cellulose and amylopectin
- both are organic compounds + carbohydrates
State similarities between cellulose, amylose and amylopectin
-all form glycosidic bonds
-insoluble
-wont affect water potential, no osmotic affect, cell wont burst or become turgid
-free ends for glucose monomers to join or break off
-all polysaccharides
What are properties of cellulose
-structure+ strength for cell wall
-forms long straight chains held together by hydrogen bonds to form fibrils
State similarities between glycogen and amylopectin
-form 1-4 glycosidic bonds between monomers and 1-6 glycosidic bonds between branches
-highly branched, rapid hydrolysis
State similarities between amylose and amylopectin in terms of energy storage
they are both found in plants
State similarities in terms of energy storage between glycogen, amylose, and amylopectin
-made of preferred respiratory substrate
-alpha glucose
-all form glycosidic bonds
- all polysaccharides
- all carbohydrates
-insoluble- wont affect water potential so no osmotic effect so no cell lysis or become turgid
-all used for energy store
Chitin is made up of a macromolecule - N-acetylglucosamin . How does the composition of the N-acetylglucosamin differ from the composition of a monosaccharide sugar.
It is a macromolecule that contains nitrogen (NHCOCH3)
Compare 3 structural differences between Amylose and Cellulose molecules
Amylose:
-coiled
- no hydrogen bond
- form 1-4 glycosidic bond (alpha monosaccharides)
- alpha glucose monomers
Cellulose:
-no coiling
- contains hydrogen bonds to link chain to form fibrils
-forms 1-4 glycosidic bond ( beta monosaccharides)
-beta glucose monosaccharides
Which properties of cellulose make it suitable for forming cell walls
-forms long straight chains- held in parallel by many hydrogen bonds which provide collective strength ( this then forms fibrils)
- insoluble- water potential wont affect + no osmotic affect- means cell will not become turgid or cause cell lysis
Describe the formation of cellulose
Condensation, polymerisation of beta glucose molecules
Name the carbohydrate molecules used to store energy in plants and animals
Plants= starch (amylopectin + amylose)
Animals= glycogen
Glycogen forms a lot of 1-6 glycosidic bonds to produce…
a highly branched molecule for rapid release of alpha glucose
Mammals convert the monosaccharide glucose into a highly branched polysaccharide called glycogen which gets stored in liver cells. Explain why Mammals store glycogen instead of glucose
-Mammals store glycogen as it is insoluble so wont affect water potential so no osmotic affect + cell lysis wont occur
- it is stored as glycogen as glycogen can be rapidly hydrolysed and glucose can be used for energy
-it has a lot of branches so it is very compact ( ideal for storage takes up less space)
Give 3 properties of cellulose that make it suitable as the basis of plant cell walls
1) forms strong hydrogen bonds - strengthens+ supports structure of cell
2) insoluble so wont affect water potential in plant cells- will have no osmotic affect so cell wall wont become turgid
3) unreactive or inert
State one property of glucose that allows it to be easily transported in animals
It is polar and soluble- therefore can be carried in solvents
Explain how the structure of glycogen differs from that of amylopectin to make it better suited as an energy store in animals
-glycogen has more 1-6 glycosidic bonds- meaning more glucose monosaccharides can be formed when glycogen is hydrolysed
-glycogen has a lot more branches- it is much more compact and takes up less space- it is ideal for storage
- glycogen has more free ends when blood glucose levels are too high glucose can be added to the chain of polysaccharides and stored in the form of glycogen
True or False:
Amylose is soluble
False
True or False:
Amylose is formed by condensation reactions
True
True or False:
Amylose is branched
False
What elements are lipids made from
Carbon, Hydrogen, Oxygen and sometimes phosphorus
What are lipids not
Not polymers
What are lipids
macromolecules made up of large sub units that are not the same hence they are not polymers
What is the property that all lipids have in common
They are insoluble in water, so do not dissolve in water. This is because they are mostly non polar structures. This means that they have a hydrophobic property
List 5 properties of lipids
-macromolecules
- not polymers
- insoluble
- non-polar
-hydrophobic
-dissolves in organic solvents such as ethanol
What do lipids dissolve in
Organic solvents such as ethanol
What is a triglyceride made up of
It is made up of 3 fatty acid tails and a glycerol molecule
Draw out the structure of cellulose
carbohydrate booklet page 3
Draw out the structure of amylopectin
carbohydrate booklet page 3
Draw out the structure of amylose
carbohydrate booklet page 3
Draw out the structure of glycogen
Carbohydrate booklet page 3
Draw out an alpha glucose
Carbohydrate booklet page 4
Draw out a beta glucose
carbohydrate booklet page 4
Draw out ribose and deoxyribose- circle the difference
Carbohydrate booklet page 5
Draw out the synthesis of maltose
page 10 carbohydrate booklet
Draw out the synthesis of lactose
page 10 carbohydrate booklet
Draw out the synthesis of sucrose
page 11 of carbohydrate booklet
Draw out breakdown of maltose
Page 12 carbohydrate booklet
Draw out the breakdown of lactose
page 13 carbohydrate booklet
Draw out the breakdown of sucrose
page 12 of carbohydrate booklet
Show 1 to 6 glycosidic bond between alpha glucose and fructose
q 4 page 17 carbohydrate booklet
Close up of bonding of polysaccharide including branches draw it out
page 23 carbohydrate booklet
Draw the structure of triglyceride include the glycerol and fatty acids
Lipids booklet page 4
Draw out the glycerol molecule
Lipids booklet page 4
Draw out the fatty acid chains
Lipids booklet page 4
How can triglycerides differ from each other
-their tales can be saturated or unsaturated
- their tales can be different lengths
What does it mean if a fatty acid is saturated
It contains a lot of hydrogen atoms- it is ‘full’ of as many hydrogens as possible
- saturated fatty acid has no C-C double bonds
What is the general formula for a fatty acid
CN H2N+1 COOH
Draw out the carboxylic acid group on a fatty acid tail
Lipids booklet page 5
What does a monosaturated fatty acid have
they have 1 C–C double bond
Draw out a monosaturated fatty acid
Lipids booklet page 6
What is the general formula for a monosaturated fatty acid
CN H2N-1 COOH
What is a polyunsaturated fatty acid
- can contain a number (more than 1) of double C–C bonds
Draw out a polyunsaturated fatty acid
Lipids booklet page 6
What is the general formula for a polyunsaturated fatty acid
can’t have a formula as it can have any number of unsaturated fatty acids
What is a phospholipid made up of
A phospholipid is made up of a glycerol backbone with 2 fatty acid ‘tails’ and I phosphate hydrophillic head attached to the glycerol molecule
How do the 2 fatty acids bond to the glycerol in a phospholipid
The 2 fatty acids bond to the glycerol via 2 condensation reactions resulting in 2 ester bonds
Draw out what a phospholipid looks like
lipids booklet page 7
What molecule forms the backbone of triglycerides and phospholipids
Glycerol
What elements are triglycerides and phospholipids made up of
They are both made up of Carbon, Hydrogen and oxygen
However phospholipids can also contain phosphate as well
Do triglycerides have a phosphate head
No
What has a phosphate head
Phospholipids
How many fatty acid tails does a triglyceride have
3
How many fatty acid tails does a phospholipid have
2
Compare the nature of fatty acid tail between triglycerides and phospholipids
Triglycerides= any combination of saturated and unsaturated
Phospholipid= 1 saturated fatty acid tails and 1 unsaturated fatty acid tail
What is a macromolecule
Molecule containing very large number of atoms built up of smaller chemical structures
Why is a triglyceride classed as a macromolecule
Because it is made up of glycerol and 3 fatty acid tails- it is not a single molecule
Why is a phospholipid considered a macromolecule
Because of its large size- and because it also contains 2 fatty acid tails and a phosphate head
What is the name of the bond between the glycerol and the fatty acid tail
Ester bond
What is the name of the functional group COOOH at the end of a fatty acid
Carboxylic acid group
What is the difference between a saturated and unsaturated fatty acid
Saturated= no C–C double bond
Unsaturated= has C–C double bond
How many double bonds does a polyunsaturated fatty acid have
Any number- more than 1 of C–C double bond
How many of the phospholipid tails are saturated
1
How can a fatty acid be joined to a glycerol molecule
In a condensation reaction
How many condensation reactions are needed to synthesis a triglyceride
3
What is the word equation for the synthesis of triglycerides
Glycerol+ 3 fatty acid chains= triglyceride + 3 water molecules
Describe the synthesis of a triglyceride
The hydroxyl groups on the glycerol molecule react with the hydroxyl group of the carboxylic acid group of the fatty acid tails in 3 condensation reaction to produce 3 water molecules and form 3 ester bonds.
Draw out the synthesis of a triglyceride
Lipids booklet page 10
Draw out the chemical shorthand version of:
-triglyceride
-saturated fatty acid
-monosaturated fatty acid
-polysaturated fatty acid
Lipids booklet- attempt question
q 1 page 11
What is the chemical formula for a glycerol molecule
The chemical formula for a glycerol molecule is C3H5(OH)3.
What enzymes are needed to catalyze hydrolysis reactions or breakdown of triglycerides
Lipase
Draw out the breakdown of a triglyceride
Lipids booklet page 10
Word equation for breakdown of triglyceride
Triglyceride+ water= glycerol+ 3 fatty acids
Describe the breakdown of triglyceride.
In the hydrolyses of triglycerides, 3 water molecules are added and these complete the hydroxyl groups on the end of each fatty acid tail and glycerol whilst breaking the ester bonds. 3 Hydrolyses reactions are needed.The reactions are catalyzed by lipase enzymes.
Attempt questions 1 and 2 in lipids booklet page 11
Draw a monoglyceride molecule
lipids booklet page 12
Name the bond formed between the glycerol and fatty acids
Ester bond
Name the other molecule formed when this bond is made
Water
Using the structure of triglyceride molecules as an example, explain what is meant by hydrolyses.
Hydrolyses is the breakdown of the 3 ester bonds between the glycerol and fatty acids using 3 water molecules. 1 water molecule reacts with each ester bond, 3 fatty acids and 1 glycerol molecule is produced.
Attempt question 5 a in lipids booklet page 13
What are lipids
lipids are made up of 2 molecules, fatty acids and glycerol and they do not form polymers
How are triglycerides formed
Triglycerides are formed via the condensation between 1 molecule of glycerol and 3 molecules of fatty acids. This forms a ester bond between the R group and COOH group
Compare saturated and unsaturated fatty acids.
Saturated fatty acids= the hydrocarbon chain has only single bonds between carbons
Unsaturated fatty acids= the hydrocarbon chain consists of at least 1 double bond between carbons
The R groups of fatty acids can be saturated or unsaturated
Give a description of the structure of triglycerides
- Formed via 3 condensation reactions between one molecule of glycerol and 3 molecules of fatty acids, 3 ester bonds form.
-3 Water molecules are removed - R group saturated and unsaturated
- saturated hydrocarbon chain has only single bonds between carbons
-unsaturated one double C–C bond
List some functions of triglycerides
- energy store
- metabolic water source=do not affect water potential
- stores unused calories and provide your body with energy and excess fatty acids
- helps to insulate the body and protects vital organs
Relate the structure of triglycerides to their function
- can transfer energy due to large ratio of energy storing C-H bonds compared to no. of carbon atoms- a lot of energy can be transferred when it is broken down or stored within molecule
2) Due to high ratio of H to O atoms; they act as a metabolic water source -because triglycerides can release water when they oxidized= essential for animals in the dessert such as camels when there is very little water present
3) As lipids (triglycerides) are large, hydrophobic molecules they are insoluble in water- means they will not affect the water potential and osmosis
4) Lipids are negatively low in mass. This means a lot can be stored in an animal without it increasing the mass and preventing movement.
Describe the structure of a phospholipid
-Hydrophilic heads of phospholipid can attract or interact with water as it is charged
- due to the phosphate being charged it repels other fats.
-The fatty acid chain is not charged (hydrophobic tail)- it repels water but will mix with fats
-because of these two charged regions- they are polar
- in water they are positioned so that the heads are exposed to water and the tails are not
What is a phospholipid made up of
A phosphate head attached to a glycerol and 2 fatty acid tails
What is the function of phospholipids
-Can form a phospholipid bilayer structure
-allows multiple cellular processes to occur in sub-cellular compartments
-maintains integrity+ stability of cells
Relate the structure of a phospholipid to its function
In water they are positioned so that the heads are exposed in water and the tails are not- forms a phospholipid bilayer membrane structure which makes up the plasma membrane around cells- acts as barrier separating outer environment to inner molecules- it controls substances in and out of cell
-electrical insulation- cell content is maintained- partially permeable so nerves or neurons are surrounded by amylin sheath which act as an electrical insulation
What is cholesterol made up of
27 carbon compound with unique structure with a hydrocarbon tail, a central sterol nucleus made of four hydrocarbon rings, and a hydroxyl group
-made up of lipids
Cholesterol is made up of…
lipids
What is the function of cholesterol
-storage
- maintains/ regulates fluidity of cell surface membrane and its permeability
Relate the function of a cholesterol to its function
-Lipids have relatively low mass- T/ F a lot can be stored without increasing the mass + preventing movement
-Fluidity stabilizes membrane- allows cell membrane to retain fluid but reduces the over all fluidity of the membrane- prevents phospholipids from coming into contact and stiffening or crystalizing
-Permeability= within cell membrane- by phosphate heads and fatty acid tails- embedded= if too much fluid too many molecules would be able to pass into cell if too stiff not enough molecules will be able to pass into cells
- Cholesterol helps reduce the fluidity of membranes at high temperatures and increase fluidity at low temperatures
Why is cholesterol different in its structure
-different in structure as it is a sterol
-sterols have 4 carbon rings and a hydroxyl group at one end and they both have hydrophobic and hydrophilic regions
What is the difference between HDL and LDL and which one is ‘good’ and which one is ‘bad’ and why ?
-HDL carries cholesterol to your liver, where it can be removed from your bloodstream before it builds up in your arteries- helps rid your body of excess cholesterol so it’s less likely to end up in your arteries
-LDL is called “bad cholesterol” because it takes cholesterol to your arteries, where it can collect in your artery walls.
-This is bad especially the build up of cholesterol in coronary arteries- which supply blood to the heart- it narrows the blood vessels so less oxygenated blood can pass through to the arteries and tissues of the heart- depriving it from oxygen and resulting in heart attacks
Fill in the blanks=
Lipids are a diverse group of chemicals that are neither polar nor charged and hence are insoluble in water. The (1) nature of the heads of phospholipids allows them to form the membranes. (2) also contain fatty acids and form part of the membrane. Lipids can be used for energy storage in the form of (3). Some hormones are also lipids and they are similar in structure to (4)
1= hydrophilic
2= glycolipids
3=triglycerides
4= cholesterol molecules
Why can lipids increase the buoyancy of aquatic animals
Lipids can increase the buoyancy of aquatic animals as they are less dense ( low density lipoproteins) than proteins which makes them more dense
Unsaturated fatty acids contain fewer what?
hydrogen atoms, because they contain at least a C–c double bond
Lipids are insoluble so how are they transported in the blood
Lipids are insoluble so need to be transported in the blood by lipoproteins
What is cholesterol used to synthesize
Bile and Steroid hormones e.g. estrogen, progesterone
Name 3 function of triglycerides in living organisms
1) energy storage
2) Electrical insulation
3) Thermal insulation
Explain why melting points of methyl Esters might decrease as the molecular formula increases
M.p decreases as fewer carbon hydrogen bonds are formed, meaning molecules are becoming less saturated and there are more double bonds, hence the low m.p
True or false=
Cholesterol binds to phospholipid fatty acid tails, increasing the packaging of the membrane, therefore reducing the fluidity of the membrane
True- explains function of cholesterol in cell surface membrane in the human body
Synonym for proteins
Polypeptides
Define Proteins/ polypeptides
Proteins are made up of many amino acid monomers
What is the most diverse biological molecule in its structure and function
Proteins
What helps a protein perform a specific function
It is the specific shape of each protein that adapts it to perform a specific function
Draw out the general structure of amino acids
Protein booklet page 4
What do all amino acids contain
-amine group
-carboxylic acid group
-central atom
- R group
What do different amino acids have
Different R group
What is the R group also known as
The variable group
How many different important biological amino acids are there with different R groups
20
What is the reaction that joins up 2 amino acids
Condensation reaction
What are 2 amino acids joined together called
Dipeptides
Many amino acids joined together are called what
A polypeptide
Describe how a peptide bond is formed between 2 different Amino acids
The hydroxyl group of the carboxylic acid group of one amino acid reacts with a hydrogen atom on the amine group of a second amino acid in a condensation reaction. A water molecule is released and a peptide bond is formed
Have a go at the 4 questions on page 6 of the protein booklet
make sure you can do this with any given amino acids
tip= know the basic structure of an amino acid very well
How is a polypeptide formed
-By repeated condensation reactions between many amino acid monomers
Explain what happens when a condensation reaction occurs to form a polypeptide- more about the ‘free’ ends
-as condensation reaction is between each adjacent amine and carboxylic group the completed polypeptide has a ‘free’ amine group called the ‘N- terminus’ at one end and a free carboxylic acid group at the other end called a ‘C-terminus’
How are dipeptides and polypeptides broken down
Broken down by hydrolyses reactions catalyzed by enzymes
What is the name of the enzyme that breaks down poly and di- peptides
Peptidase
What is the name of the enzyme that breaks down proteins
Peptidase
Describe the reaction that takes place when a dipeptide or protein is broken down to form amino acids
Polypeptidase enzymes catalyze a hydrolysis reaction between the dipeptide and water. The water molecule reacts with the peptide bond breaking it and reformed the amine and carboxylic acid groups on the adjacent amino acids.
Have a go at the 4 questions on page 9 in the proteins booklet
Learn to be able to identify how to break and make peptide bonds, do this with good knowledge of the amino acid general formula and condensation and hydrolysis reactions and what groups are involved
Student A said= An amino acid has no carboxylic acid group. Is it still classed as an amino acid. Help explain to Student A your thoughts on this question.
An amino acid must contain a carboxylic acid group without it peptide bonds cannot be formed or broken down
Have a go at Q 2 and 3 in protein booklet
On page 11 and 12
The R group in amino acid Alanine is CH3. Describe the structure of the amino acid Alanine
Alanine has
- an amine group consisting of nitrogen and hydrogen ( NH2) which is bonded to carbon in the middle
-The carboxylic group (COOH) is opposite the amine group and is bonded to central carbon atom
-R group CH3 is bonded to central carbon atom opposite to Hydrogen which is also bonded to central carbon atom
Name the covalent bond between two adjacent amino acids in a chain of amino acids
Peptide bond
Q5 and 6 on page 13+ 14 of proteins booklet
do it- you need to check and reinforce understanding
The process of esterification leads to the formation of ester bonds during the production of triglycerides. Describe what is meant by the term esterification.
- reaction between carboxylic acid and alcohol
-reaction between fatty acids and glycerol
-condensation reaction- removal of water
True or false=
Not all proteins have all 4 levels of structure and some of them even have extra bits
True
Describe the primary structure of a protein
The primary structure is the order or sequence of the amino acids in the polypeptide chain and the peptide bonds between them. It is determined by the sequence of bases on the gene that codes for t the protein.
Proteins are made up of one or more large polymers creating a… what ?
Macromolecule
What are the 4 level of proteins
Primary
Secondary
Tertiary
Quaternary
Describe the secondary structure of a protein
-two types of secondary structure: alpha helix and beta pleated sheets.
-are both created by the formation of hydrogen bonds between the the carboxylic acid and amine groups of 2 amino acids
Describe the tertiary structure of a protein
-tertiary structure described as the overall 3d shape of protein
-created by bonds that form between the R groups (side chains) of the amino acids
-The tertiary structure of each protein is unique because different R groups have different properties which make them form different types of bonds
What are the R groups also known as
side chains
Why is the structure of each protein so unique
Because different R groups have different properties which make them form different types of bonds
Draw out the primary structure of a protein
Protein booklet page 15
Draw out the secondary structure of a protein
Protein booklet page 16
Draw the tertiary structure of a protein
Protein booklet page 16
Name all the bonds that could occur between the tertiary structure
Hydrophobic interactions
Hydrophilic interactions
Disulphide bonds
Hydrogen bonds
Ionic bonds interactions
How many bonds can occur between tertiary structure of a protein
5
Explain how the hydrogen bonds could occur in a tertiary structure of a protein
These are weak bonds formed between polar R groups
Explain how ionic bonds or interactions could occur in the tertiary structure of a protein
-Weaker bonds formed by attraction between oppositely charged R groups
-These are not true ionic bonds because there is no transfer of electrons from one atom to another
- They should be called ionic interactions
Explain how the Disulphide bonds could occur in the tertiary structure of a protein
-Covalent bonds formed between Sulphur containing R groups
- These are the strongest type of bond in the tertiary structure
What is the strongest bond formed in a tertiary structure
Disulphide bonds- covalent bonds
Explain how hydrophobic interactions could occur in the tertiary structure of a protein
-Non polar R groups are hydrophobic
- they are repelled by water found in the cytoplasm so cluster together on the inside of the protein as far away from the water as possible
Explain how the hydrophilic interactions could occur in the tertiary structure of a protein
Polar R groups are attracted to water so they orientate themselves towards the outside of the 3D shape
What are the ionic bonds formed between in the tertiary structure of a protein
Strong bonds formed between R groups of different amino acids
What are the Disulphide bonds formed between in the tertiary structure of a protein
Strong covalent bonds formed between R groups of 2 amino acids that contain sulphur
What must be present in order for the Disulphide bond to occur
Sulphur present in the R groups of the amino acids for bond to occur
Describe the Quaternary structure of a protein
-made up of more than one polypeptide chain so have quaternary structure which includes different amino acid chains and bonds between them
-bonds that hold structure in place can be any of the types that are found in the tertiary structure
What are conjugated proteins and where are they found
-Have 1 or more non protein groups attached to them that help them to carry out their function
-the non protein groups are called prosthetic groups
What are the prosthetic groups also known as
Permanently attached groups
Give an example of a protein that has a prosthetic group present
Glycoproteins- proteins with sugar chains attached that are found in the cell surface membrane and involved in cell signaling
Is conjugation a part of the quaternary structure
Conjugation is not part of the quaternary structure it is a separate feature that can occur with or without the quaternary structure
The primary structure is the order of amino acids. Precisely where is the code that determines the order of the amino acids in a polypeptide chain.
It is determined by the sequence of bases on the gene that codes for protein found the DNA
What is the name of the type of bond in the tertiary structure
Hydrogen bonds
Describe the reaction that occurs between Amino acids to form a polypeptide chain
-condensation reaction between the carboxylic acid group and the amine group that are next to each other- this forms the peptide bonds and water is released
Which type of bond forms the secondary structure and what 2 forms can the secondary structure take
Alpha helix
Beta pleated sheets
Hydrogen bonds form between carboxylic acid and amine group resulting in alpha helix and beta pleated sheets
Which bond is the strongest bond in a tertiary structure
Disulphide bonds- covalent bonds between Sulphur containing R groups are the only offered covalent bonds
How is a protein with a quaternary structure different to one without this level of structure
A protein with quaternary structure has many polypeptide chains- are held together by 2 Disulphide bonds, third Disulphide bond would mean it is part of the tertiary structure
Do question 10 on page 21 in the protein booklet
Describe how R groups can interact to determine the tertiary structure of the protein
Name bonds and describe what they do their properties
Which bond is not formed when a conjugated protein folds into its quaternary structure
A= Disulphide
B= Hydrogen bonds
C= peptide bonds
D= ionic
C- peptide bonds occur in the primary structure
What is the function of globular proteins
- are functional proteins as they carry out specific functions in the body as opposed to being structural
- They include enzymes, hormones and transport proteins such as protein
Describe the structure of globular proteins
Compact and spherical in shape due to clusters of hydrophobic R groups on the inside of the protein and hydrophilic R groups on the outside (in the cytoplasm)
Properties of globular proteins
-Water soluble, many hydrophilic R groups on outside of the polypeptide chains- make them water soluble
-means they can be easily transported in the blood
-Specific shapes and irregular arrangements of amino acid gives them very precise shapes needed for their function e.g.
-Enzymes have specific shaped active site
What are globular proteins known as
Functional proteins
Globular or functional proteins have relatively unstable structure, how can this affect the proteins
-Relatively unstable structure makes proteins sensitive to their environment -means their action can be controlled by changes to environment
-many of these bonds are weak + susceptible to effects of a changing environment
- e.g. Ionic interactions can be broken by an increase or decrease in PH and hydrogen bonds are easily broken by vibration at higher temperatures
-These bonds are critical for maintaining the shape and function of these proteins
How is hemoglobin adapted or structured for its function
Hemoglobin= quaternary protein made up of 4 polypeptide chains joined together- 2 Alpha and 2 beta sub-units
Each unit contains prosthetic Fe2+ group in each Haem group- red oxygen carrying pigment found in RBC
- this is what enables hemoglobin to bind to oxygen in the lungs and transport around the body in the cells that need it where it is released
How is insulin adapted or structured for its function
Insulin= quaternary protein- globular protein, made up of 2 polypeptide chains joined together by Disulphide bonds
-when in pancreas six of these molecules bind together to form a large globular protein
-hormone secreted by pancreas, helps to regulate blood glucose concentration
-hormones transported through blood stream to the tissue where it acts so needs to be soluble
- also have to fit into receptors, specific receptors on cell surface membranes to have their effect and therefore need to have precise shapes
How is salivary amylase adapted or structured for its function
Salivary Amylase= Quaternary protein contains 4 Haem prosthetic groups
- Fe2+ ions in prosthetic groups - allow catalase to interact with hydrogen peroxide+ speed up its breakdown
-hydrogen peroxide= common by product of metabolism but is damaging to cells and cell components if allowed to accumulate
- catalase makes sure this doesn’t happen
-primary structure consists of 496 amino acids
-secondary structure contains sections of both alpha helix and beta pleated sheets
-tertiary structure contains 5 Disulphide bonds amongst larger numbers of hydrogen and ionic bonds
Amylase =enzyme, catalyses the breakdown of starch in the digestive system
- Catalase= enzyme, catalyzes reactions+ increase reaction rates - each enzyme is specific to a particular reaction or type of reaction
Summarise the structure of globular proteins
Then state what property the structure gives it
How does property link to function
Structure 1:
-spherical in shape
-many hydrophilic R groups on the outside
-many hydrophobic R groups on the outside
Property 1:
-compact + water soluble
Function 1:
-transported easily around the body
Structure 2:
weaker bonds in tertiary and quaternary structures
Property 2:
unstable
Function 2:
sensitive to change in environment
Structure 3:
Irregular amino acid sequences
Property 3:
unique shapes
Function 3 : cell signaling- hormones, enzymes- active site
Function of Fibrous proteins
Fibrous proteins are usually structural proteins- used to build+ strengthen and protect cells and tissues
Structure of Fibrous proteins
Strong, insoluble molecules with a high proportion of hydrophobic R groups in their primary structures
-Repetitive amino acid sequences, leading to very regular, linear structures
Properties of Fibrous proteins
-long
- strong
-insoluble in water
In the primary structure of collagen every third amino acid is…
-Other common amino acids are…
every third amino acid is glycine
other common amino acids are proline and hydroxyproline
What does collagen, keratin and elastin make up
Collagen= Skin
Keratin= hair+ nails
Elastin= alveoli in lungs + skin
Keratin is a Fibrous protein- explain its structure, property and function
-has a large proportion of Sulphur containing amino acid, cysteine
-this results in many strong Disulphide bonds (Disulphide bridges) forming strong, inflexible, and insoluble materials
-degree of Disulphide bonds determines the flexibility- hair contains fewer bonds making it more flexible than nails, which contains more bonds
- unpleasant smell produced when hair or skin is burned is due to presence of relatively large quantities of Sulphur in those proteins
Elastin is a Fibrous protein- explain its structure, property and function
- found within elastic fiber’s, e.g. in the walls of blood vessels & surrounding the alveoli in lungs
-Elastin is actually made up from many stretchy protein fiber’s called ‘tropoelastin’
-These have the ability to stretch and recoil, helps in blood vessels especially arteries that transport blood at higher pressures around the body
Collagen is a fibrous protein- explain its structure, property and function
-a fibrous protein
-it is a connective tissue, found in skin, tendons, ligaments, and the nervous system
- there are a number of different forms but all are made up of 3 polypeptides wound together in a long and strong rope like structure
-like rope collagen has flexibility
true or false:
3 polypeptide chains form a triple helix
true
It is what collagen is made up of
Globular vs Fibrous
Shape=
Purpose (function)=
Amino acid sequence=
Durability=
Examples=
Solubility=
Globular:
S= spherical
P= functional
A= irregular
D=very fragile
E= enzymes, hormones, hemoglobin
S=soluble in water
Fibrous:
S= linear, long molecules
P= structural
A= regular
D= very strong- stable
E= keratin, collagen, elastin
S= insoluble in water
How can you remember the properties of proteins
Using SPADES
What does SPADES stand for
S= shape
P= purpose (function)
A= Amino acid sequence
D= Durability
E= examples
S= solubility
What is a similarity between globular and functional proteins
Both are proteins made up of polypeptide chains
- Both contain a hydrophobic and a hydrophilic group
Why are computer modelling of proteins useful and what are they
Computer modelling systems= predict the structure of protein based on its amino acid sequence (primary structure)
It uses prior knowledge to make predictions about new proteins
Useful= because protein structures can be used in medicine e.g. knowledge could be used in production of synthetic antibodies, enzymes, hormones etc.
What are the 2 different approaches of Computer modelling of protein
1) Ab initio protein modelling
2) Comparative protein modelling / Protein threading
What is Ab initio protein modelling
-Computer interprets physical+ electrical properties of atoms of each amino acid present
-uses this info to predict possible outcomes in terms of secondary & tertiary structure of the final protein
- sometimes there are several different outcomes
What is comparative Protein modelling/ Protein threading
-scans amino acid sequences against a data base of known protein structures
- produces models of what the final structure of the protein might be
- there may be more than one possible outcome
Genes code for what
Proteins
What is protein misfolding
-base sequence of genes determines amino acid sequence of polypeptide
-if mutation happens in genetic sequence, alternative amino acid could be inserted into polypeptide chain or polypeptide chain could be cut short
-either of these effects will change the way the proteins fold
-means protein may not function properly
What is cystic fibrosis, whats the cause of it
Genetic disease caused by misfolding of a membrane protein
- called cystic fibrosis transmembrane conductance regulator (CFTR)
- most common mutation for gene in this protein results in the deletion of an amino acid, called phenylalanine, at position 508
-this causes protein to misfold, so that chloride ions can no longer pass along the pore in the protein
-this results in build up of thick, sticky mucus int the lungs, as well as other symptoms
What does CFTR stand for
Cystic fibrosis transmembrane conductance
Name the bond that are present in the tertiary structure of a protein and the parts of the amino acids that these bonds are between
Tertiary structure held together by multiple bonds ( hydrogen bonds, Disulphide bonds, and ionic interactions) which form between atoms on adjacent amino acids i
In people with cystic fibrosis the CFTR protein is mutated. The most common mutation is the deletion of one amino acid. How could the deletion of one amino acid affect the folding of the protein
Atoms on adjacent amino acids will be different, which will affect bonds or interactions between amino acids when the proteins fold- changing its structure
Explain how change in the structure of a protein could affect its properties
-protein misfolds
- CL- ions can no longer pass through pore in the protein
-results in build up of thick, sticky mucus in the lungs
Compare protein modelling with being able to see the protein structure directly, e.g. with an electron microscope. What is an adv and a disadv of modelling software
Adv= can view many different proteins, ease of you e.g. you can do it without any specialist equipment ( just a computer)
Disadv= protein isn’t viewed in site (cells or tissues) so can’t be used to study interactions e.g. between protein/ drug and hormone
Scientists use modelling software to predict the shapes of proteins. Describe the feature of modelling software, that helps scientists to make predictions about proteins
-it shows the individual polypeptides and the type of secondary structure it contains is shown
-you can zoom into the protein to see the structure more clearly / individual amino acids
Suggest how protein modelling could help to develop new treatment or even a cure for cystic fibrosis
- the effect of a specific mutation in the DNA / change in amino acid in the tertiary structure
- The reason for the difference between a normal protein and a misfolded one in terms of a primary structure
are both shown so cures or treatments can be used to directly compare how structure would change to help a person with cystic fibrosis
Fill in the blank:
The secondary structure of a protein may contain many regions folded in zig zag patterns known as …..
Beta pleated sheets
Fill in the blank:
The secondary structure of a protein is determined by the arrangement of ……. bonds which stabilize the structure
Hydrogen bonds
The ….. structure of collagen is described as a left handed helix because of the direction in which the polypeptides twist.
Secondary
Polypeptides known as alpha and beta …… form part of the …… structure of haemoglobin
sub-units / chains
quaternary
Collagen is a fibrous protein. State 3 properties of a fibrous protein that are different from those of a globular protein
-insoluble
-strong
-unreactive
Do question 3 and 4 on page 39 in protein booklet
good practice of knowledge application
Describe and explain why Collagen is a fibrous protein
- it is a long chain of amino acids
-has little to no tertiary structure
-insoluble and has many non-polar amino acids
-has only 2 different amino acids- glycine and proline- small range of amino acids - has a structural function and provides strength to the artery wall
Suggest why collagen is such a strong molecule
-has many hydrogen bonds between polypeptides and has many covalent bonds between collagen molecules
-polypeptides also overlap
Which of these is a function of fibrous proteins?
A= aids rigidity of membrane
B= involved in cell signaling
C= provides elasticity in alveoli
D= speeds up reactions
C
Explain how hydrophilic and hydrophobic interactions contribute to a spherical shape.
Hydrophobic regions /R groups are on the inside of the molecule/ protein and the hydrophilic regions R groups are on the outside of the molecule/ protein
Describe the differences between Globular and Fibrous proteins using haemoglobin and collagen as examples.
( 8 marks)
Globular=
-spherical
-hydrophilic R group /regions are on outside of 3D structure and hydrophobic R groups/ regions are on inside of 3d structure
-they form Hydrogen bonds with water
- are soluble e.g. insulin
-Hemoglobin transports O2 / CO2 +contains a prosthetic group (haem group has Fe3+ ions to allow oxygen to be carried)
- polypeptide chains within hemoglobin have tertiary structure (in a ball/ spherical shape)
Fibrous=
-linear/ long chains
- chains can form hydrogen bonds with adjacent chains within a molecule
- insoluble / has few hydrophilic groups
- strong- provides strength, has a structural role
- has high proportion of glycenine so chains can lie close together
-collagen forms crosslinks/ covalent bonds between molecules
- the crosslinks / ends of molecules are staggered to avoid weak points
Collagen forms part of cartilage/tendons /ligaments / connective tissue
Identification of lipids
-insoluble
-fatty, waxy, oily compounds- soluble in organic solvents
-insoluble in polar solvents e.g. water
Explain why lipids are insoluble
because of the hydrophobic tails which repel water
Margarine vs butter (hydrogenation)
Margarine is made from oil that has been infused with hydrogen atoms, firming it into a somewhat solid form
allows margarine to contain less saturated fat than butter
What is a sterol
lipid- regulates biological processes and sustains structure membrane
what is fat under skin called
Subcutaneous fat- long term energy storage
What is Viceral fat
around organs for protection
Why is water described as being polar
There is an uneven charge distribution across the molecule. Oxygen is delta negative and bigger than electropositive hydrogen atoms, so attracts electron strongly towards it
What is metabolism
the chemical reactions in the bodys cells that changes food into energy
What is the carbohydrate monomer called
monosaccharides
What is the carbohydrate polymer called
polysaccharides
what is a 3 membered ring called
carbohydrates
Triose
what is a 5 membered ring called
carbohydrates
pentose
what is a 6 membered ring called
carbohydrates
hexose
What is the function of proteins
-helps repair + builds your bodys tissue
- secondary source of energy
- structure= collagen, keratin, etc.
-transport= haemoglobin
Amino acids in plants
- synthesized in the chloroplast and transported into cytosol for protein synthesis + secondary metabolite production or transported and stored in the vacuole
Amino acids in animals
found in muscles and tissues- get there from eating plants
Why are some amino acids essential amino acids
not synthesized by mammals therefore dietarily essential
Describe the formation of peptide bonds
Covalent bonds between 2 adjacent amino acids in a chain of amino acids
Where are proteins synthesized
Ribosomes in a cell in which protein synthesis takes place
How are polypeptides synthesized
transcription and translation
- a long chain of amino acids emerges as the ribosome decodes the mRNA sequence into a polypeptide or a new protein
Increasing temperature on tertiary structure and protein function
As you increase temperature, bonds in the active site begin to break and the tertiary structure is disrupted- alters specific shape of active site so it may no longer be complementary to substrate
Enzymes that breakdown peptide bonds
Protease
Hydrochloric acid
How do you calculate the different possibilities of amino acid sequences
20n
n= number of amino acid
Excess amino acid in the body
The body has no capacity for mechanisms for their storage
What happens to excess amino acids
It is converted into glucose or ketones or they are decomposed
How do you test for starch and what is the positive result
Iodine solution
positive result= turns blue/ black
Describe the method for testing for starch
Add 1cm3 of sample to a dimple in the spotting tile
Add a few drops of KI solution
observe colour change
How do you test for proteins
and what is the positive result
Biuret solution
positive result= purple /lilac
Describe the method for testing for proteins
Add 2cm3 sample solution to a test tube
Add 2cm3 of biuret solution
Observe colour change
How do you test for lipids
Emulsion test
positive test: milky/ cloudy emulsion
Describe the method for testing for lipids
Add 1cm3 of ethanol to a test tube
Add 1cm3 of sample
Shake vigorously to dissolve solution
Add 1cm3 of cold water
How do you test for reducing sugars
what is the positive result
Benedicts solution
Positive result = green/ red colour or brick red percipitate
Describe the method for testing for reducing sugars
Add 2cm3 of sample solution to a test tube
Add 2cm3 of benedicts reagent
Heat gently in a warm water bath to 85*c for 2 minutes
observe colour change
How would you test for non reducing sugar
What is the positive result
Acid hydrolysis- used for any solution that gives a negative benedicts test
positive result= green/ red colour, or brick red precipitate
Describe the method for testing for non reducing sugars
-Add 2cm3 of sample solution to a test tube
-Add 1cm3 of 1m HCl
-Boil in a water bath for 1 minute
-Carefully neutralize with
-Sodium hydrogen carbonate powder (Effervescence will occur)
-Check pH with indicator paper
-Add 2cm3 of sample solution to a test tube
-Add 2cm3 of benedicts reagent
-Heat gently in a warm water bath to 85*c for 2 minutes
-Observe colour change
Enzymes are important biological molecules. a student decided to use the biuret test to detect the presence of enzyme in a solution. Outline the procedure the student should follow in order to detect the presence of enzyme in a solution using a biuret solution
Add biuret solution to sample and observe the colour change - should go lilac if protein is present
Describe how to do the emotion test for lipids and how a positive would be identified
Add ethanol to sample ,shake vigorously then add water - for a positive result the sample should show a milky emulsion / should go cloudy
biology PAG booklet page 13 Q2,3
Q1 page 4 2.1.2 BioMol booklet
A vet is concerned that a llama is unwell. Vet suspects there maybe hemoglobin in the urine of the lama explain how the vet could confirm the suspicion
-Add biuret solution to urine
-observe colour change (should go from blue to lilac or purple )
-then compare this to urine of llama that does not contain any protein
Describe how to do the emulsion test for lipids and a positive result would be identified
-Add ethanol to sample
-shake vigorously
-Add water to it
-Observe colour change -should turn into a milky emulsion
Some organisms use a disaccharide called trehalose as a respiratry substrate.Trehalose has a similar structure and a very similar chemical properties to sucrose suggest how you could test for the presence of trehalose
-you could use the benedicts solutions and do the benedicts test
-Boil with dilute HCl and retest with bendict solution
what is chromotography
Method of separating mixtures of biologically molecules
-Phisical process = no chemical reaction and no new substances made
What is the stationary phase
filter paper or a silicaplate
how does paper chromatography work
because each chemical/ b.m will be attracted to the stationary phase to a different to a extent
-components of mixture are separated on basis of the solubility in solvent
what compounds will travel furthest up the stationary phase before precipitating out creating a mark on the paper
more soluble compounds
what is the mobile phase
travels up the stationary phase dissolving
chemicals which are strongly attracted to the stationary phase will….
will not move far
chemicals which are weakly attracted stationary phase will..
move further up the paper
What will happen to a pure chemical on the chromatography paper
will produce single spot in all solvents
Chemical in mixtures may…
separate into different spots depending on solvent
Why do we draw the starting line in pencil on chromatogram
-pencil is insoluble if we drew it with pen- which is soluble the ink would travel up the chromatogram with the solvent
What is the stationary phase in chromatography and why
paper- it does not move
what is called the mobile phase in chromatography and why
Solvent because it moves up the paper
Ho do we know whether a substance is pure or a mixture in paper chromatography
Pure= will produce a single spot in all different solvents
Mixture= will produce several spots / move up the chromatogram with the solvent
How does paper chromatography allow us to separate mixtures
Allows us to separate substances based on their different solubilities
What is the solute
Dissolved in the solvent
What is the solvent
Dissolves the solute resulting in a solution
What does soluble mean
Can dissolve in water
What does insoluble mean
Can’t dissolve in water
Describe the method in investigating a solute using paper chromatography
1) Draw horizontal line 2 cm from bottom of chromatogram- in pencil
2) Place first dot on line 2cm from one end of chromatogram- small intense spots are best
3) Place dot of another solute / pen 2cm from last dot
4) repeat until all colours are on paper /reached the end of paper
5) Use pencil to label each solute
6) hang paper in beaker using pencil and paper clips- try not to over lap paper
7) Put water into beaker with depth of 1.5cm and lower paper into beaker- ensure water is below pencil line / solute spots- paper is just touching water to allow solvent to move up paper
8) Leave for 5 minutes/ until water reaches top of paper
9) Mark with pencil level of water/ solvent at the top of chromatography paper- this is your solvent front
10) Allow to chromatogram to dry
Rf= ?
Distance moved by solute / Distance moved by solvent
How do you measure the Rf value in paper chromatography
1) Use ruler to measure distance from origin to solvent front
2) Measure distance from origin to top of each pigment spot
3) Calculate Rf value for each pigment
2.1.2 Biological molecules- PAG booklet do questions on pages 8-17
GREAT exam practice- basically all possibilities of what could come up on exam- eventually you’ll have method memorized
Valline, Citrulline, hydroxyproline and glutamic acid are amino acids that are normally found in considerable amounts of urine. Following certain diets can result in a change in the amino acids present in the urine of some people. Plan a method to compare the amino acids present in the urine of a person who has been following one of these diets with that of a person who has not.
Use chromatography paper- draw horizontal pencil line 2cm from bottom and place dots /dot shaped urine samples on top
Place in beaker with solvent- make sure solvent is below origin line and compare Rf value e.g. of urine sample or different compounds that urine samples are made of- the amino acids present etc
Collagen is a protein found in arterial walls. A collagen molecule has 3 polypeptide chains, each with 1050 amino acids, wrapped into a triple helix. A repeating sequence of the amino acids glycine and proline occur in each polypeptide chain. These amino acids have non-polar side chains. Outline the method of chromatography that will separate the main amino acids into collagen.
-draw horizontal pencil line 2cm from bottom of chromatography paper
- place dots/ dot shaped samples of amino acids- evenly spread out to avoid mixing
-use pencil+ paperclips to balance paper on top of beaker with solvent underneath
- solvent has to be below origin line
-use stain to make amino acid visible
Describe how to carry out the test for reducing sugars- Part 1 of testing glucose concentration of urine
- use permanent marker to label 7 test tubes with different concentrations + the urine sample
- Measure 2cm3 of each concentration + urine sample into correct test tubes
- Using 1cm3 syringe add 1cm3 of Benedicts quantitative solution to each test tubes
-Boil kettle+ fill beaker with freshly boiled water - Place all 7 test tubes into beaker for 5 mins
- Remove test tubes + place them all in test tube rack
–wait until all white precipitate has settled to the bottom of test tube
Describe how to carry out the test for reducing sugars- Part 2 of testing glucose concentration of urine
1) Label cuvette tray with glucose conc +urine- add cuvette in each labeled position
2) Use pipette to remove as much solution as possible from each test tube without disturbing precipitate at bottom
3) Fill labelled cuvette almost top with solution from test tube- labelled with same conc. as cuvette
4) do same with all solutions of diff conc. + urine
5) Fill extra cuvette to top with distilled water- this will be your blank
6) Make sure (680 nm) red filter is in your cuvette
7) Place blank cuvette into colorimeter- press test- should give absorbance of 0.0
8) Place one solution of cuvette into colorimeter press reading button
9) Place blank cuvette- press test
10) Place next cuvette into colorimeter+ press reading button- record absorbance in results table
11) repeat steps 9 +10 with each cuvette including urine sample
What do you do after you have your results from colorimeter
Plot a calibration curve on graph- absorbance of each concentration of glucose (y- axis), against glucose concentration ( x- axis)
Draw line or curve of best fit
Summarize serial dilutions on page 15 of PAG booklet modules 1 &2
Need to be able to do this
- tip: draw out the serial dilutions and label them to understand what is happening to each sample
How do you know a person has diabetes ?
The normal concentration of glucose in urine is 0- 0.0008- a person with diabetes will have higher concentration of glucose in urine
Explain how glucose concentration in urine could indicate diabetes
-high concentration of glucose in sample indicates person is at high risk of diabetes- lack of insulin produced+ liver cells are sensitive to insulin- so higher conc of glucose in blood is present= leads to it not being absorbed efficiently in the kidneys so remaining glucose is still present in urine
How do you make sure that you measure the volume accurately of the glucose concentrated sample / urine
-Use 10cm3 measuring cylinder measure 10cm3 of solution
-use of one dropping pipettes
- to make sure meniscus of solution is exactly on 10cm3 line of measuring cylinder to be accurate
Why is it important to be accurate when measuring the volumes of glucose concentrated solutions
to reduce anomalies/ eliminate errors+ make sure data is accurate so result is accurate
Why do you invert test tubes when carrying out serial dilutions
To ensure that solutions are mixed properly, inadequete mixing will result in inaccurate test results
If you took 1cm3 of 5M glucose solution and added it to 99 cm3 of distilled water what would the concentration be?
0.05M
You carried out the benedicts test for reducing sugars, using benedicts qualitative solution, what colour did the benedicts reagent change into after being in the water bath
Brick red
What do different colours of benedicts reagent tell us, when reacting with reducing sugars
Can these results tell you the exact concentration of glucose present
A positive result for reducing sugars that are present
No, they are subjective to judgment
You measured the absorbance of glucose concentration using the colorimeter.
1)Describe how that colorimeter works
1) The device measures the intensity of concentration of the colour that develops upon introducing a specific reagent into solution.
You measured the absorbance of glucose concentration using the colorimeter.
Explain why it was important to use a blank cuvette to set the absorbance to 0
It is a control- to measure baseline ahylate level, so that absorbance for reducing sugars wont be affected
You measured the absorbance of glucose concentration using the colorimeter.
Why do you set the red filter to 680 nm
It must be the complimentary colour of the compound formed between benedicts and glucose concentration
You measured the absorbance of glucose concentration using the colorimeter.
Explain how a colorimeter allows you to obtain a quantitative measure of the concentration of an unknown solution
A colorimeter contains a photo cell, which is able to detect when a wavelength is passed through the sample- some of the light is absorbed and some passes through, the wavelength of light that passes through is measured
What are nucleic acids
group of information carrying molecules that collectively hold our genetic code and ensure it can be read to make proteins
The term ‘nucleic acids’ comes from the fact that…
Acids of nucleus
Deoxyribonucleic acid
Deoxyribo= contains deoxyribose
Acid= phosphate
Nucleic= of the nucleus
What are the two types of nucleic acids
DNA and RNA
What does DNA stand for
Deoxyribonucleic acid
What does RNA stand for
Ribonucleic acid
Where is DNA found and what does it carry
-in the nucleus
-carries the code to make all of the proteins in the body
What is RNA used for
-used to make proteins
What are the 3 types of RNA
-mRNA= (messenger Ribonucleic acid)
-tRNA= (transfer Ribonucleic acid)
-rRNA= ( ribosomal ribonucleic acid)
Give 2 similarities between DNA and RNA
- both polymers made up of monomers called nucleotides
Nucleotides are the monomers that join together to make what polymer
Polynucleotide nucleic acid
Nucleotides are made up of what 3 subunits
- a pentose sugar
- a nitrogenous base
- a phosphate group
What is a pentose sugar in DNA and RNA called
pentose sugar has 5 carbons- its either ribose in RNA or its deoxyribose in DNA
What is meant by a nitrogenous base
- contains nitrogen
What do bases do
code for proteins
function of a phosphate group in nucleotides
makes nucleotide acidic
How is the Nitrogenous base, the sugar and phosphate group attached together in a nucleotide
- Nitrogenous base is attached to carbon 1 of sugar ( ribose sugar e.g.)
- phosphate group is attached to carbon 5 of sugar
What sugars can form a part of a nucleotide
Deoxyribose and Ribose
What is the structural difference between ribose and deoxyribose
Deoxyribose contains 1 less oxygen from carbon 2- instead of the hydroxyl group like in ribose, it just contains H
The largest 2 bases are made up of how many carbon rings and what are they called and give examples
The largest two bases are made up of 2 carbon rings
- these are called purines
- largest 2 bases are adenine and guanine
What is a mnemonic to help you remember the largest 2 bases, their names and what are they
-Pure As Gold
- Purine= Adenine and Guanine
- They care called purines and they are adenine and guanin
What are the smaller bases called and what are they
- smaller ones are called pyrimidines
- these are known as thymine, cytosine and uracil
How many carbon rings to purines contain
2 carbon rings
How many carbon rings to Pyrimidines
1 carbon ring
Name energy carrying molecules in all living organisms
ATP and ADP
What does Uracil appear in and in place of what
Uracil appears in RNA in place of thymine
What is special about ATP and ADP
- they are phosphorylated nucleotides
ATP and ADP are both phosphorylated molecules. Explain what the term phosphorylation means.
Phosphorylation means adding
(one or more) phosphate groups to a molecule
What does ATP stand for and why
- Stands for Adenosine Triphosphate
-Because it is made up of ribose, adenosine and 3 phosphate groups
What is ATP made up of
-Ribose
-Adenosine
-3 phosphate groups
What does ADP stand for and why
- Adenosine Diphosphate
- because it is made up of adenosine, ribose and 2 phosphate groups
What is ADP made up of
-Adenosine
-Ribose
- 2 Phosphate groups
What is the one difference between ATP and ADP
ATP= contains 3 phosphate groups
ADP= contains 2 phosphate groups
Name 2 nucleotides
DNA and RNA
What pentose sugar is DNA nucleotide made up of
Deoxyribose sugar
What pentose sugar is RNA nucleotide made up of
Ribose sugar
What pentose sugar is ATP made up of
Ribose sugar
What pentose sugar is ADP made up of
Ribose
Number of phosphate groups present in DNA nucleotide
1
Number of phosphate groups present in RNA nucleotide
1
Number of phosphate groups present in ATP
3 phosphate groups
Number of phosphate groups present in ADP
2 phosphate groups
How many possible nitrogenous bases in DNA nucleotide and what are they
4
-A
-T
-G
-C
How many possible nitrogenous bases in RNA nucleotide and what are they
4
-A
-U
-C
-G
Possible nitrogenous bases in ATP
Adenine
Possible nitrogenous bases in ADP
Adenine only
A phosphate group on a nucleotide is what
-makes nucleotide acidic
-negatively charged
-inorganic
An inorganic phosphate group that is negatively charged and makes the nucleotide acidic
What is a nitrogenous base
complex, organic molecule containing one or 2 carbon rings in its structure as well as nitrogen
What type of reaction joins nucleotides together and what molecule is released
A condensation reaction and a water molecule is released for every formation of condensation reaction
What do 2 nucleotides join together to make
Dinucleotide
What do many nucleotides join together to make
polynucleotides
Both DNA and RNA are what
nucleic acids
Describe the reaction between 2 nucleotides
-The phosphate group at the 5th carbon of the pentose sugar of one nucleotide forms a covalent bond with the hydroxyl group at the 3rd carbon of the pentose sugar of an adjacent nucleotide
-These bonds are called phosphodiester bonds
-This forms a long, strong sugar phosphate backbone with a base attached to each sugar
What are the bonds called that form between 2 nucleotides
Phosphodiester bonds
What do dinucleotides form when bonded together
A long, strong sugar phosphate backbone with a base attached to each sugar
Do Q1, Q2, Q3 Q4 page 7, 8 and 9 nucleotides booklet
Do Q1 page 10 nucleotide booklet
Name the type of reaction that occurs when ATP is converted to ADP
Hydrolysis
Identify 2 similarities, 2 differences between DNA nucleotide and a molecule of ATP
Similarities =
-both have same nitrogenous base- adenine
-both have a pentose sugar
Differences =
-ATP has 3 phosphate groups
DNA has 1 phosphate group
-ATP has a ribose pentose sugar
DNA nucleotide has a deoxyribose pentose sugar
ATP is described as the ‘universal energy currency’. Describe how the structure of ATP is similar to and differs from the structure of DNA nucleotide. In your answer you should use appropriate technical terms, spelled correctly.
-Both ATP and DNA nucleotide have adenosine nitrogenous base
-Both have a pentose sugar
-Both ATP and DNA nucleotide contain a phosphate group
-DNA nucleotide has 4 bases (adenosine, thymine, guanin and cytosine) where as ATP can only have 1 base (adenine)
-DNA nucleotide has a deoxyribose pentose sugar whereas ATP has a ribose pentose sugar
Do Q 4 in nucleotide booklet page 11
State 2 differences between a molecule of ADP and a DNA nucleotide that contains adenine
-DNA nucleotide has 1 phosphate group attached to it and ADP has 2 phosphate groups attached to it
-DNA nucleotide has a deoxyribose pentose sugar and ADP has a ribose pentose sugar
ADP binds with an inorganic phosphate to make ATP. Name this reaction
Condensation reaction
Explain how water being a good universal solvent is beneficial to animals
2) Cytosol in eukaryotic + prokaryotic cells mainly water- ensures that many solutes/ solutions of ions+ molecules can dissolve within the cell and then be easily transported
-water being polar + being able to dissolve other polar substances- allows chemical reactions to occur much more frequently- important as it allows organisms to respond to their environment
Glucose is a hexose sugar and is a monomer in many carbohydrates. Name the precise group of carbohydrate molecules of which glucose is an example
Monosaccharide
The cells of living organisms require glucose. State and explain two ways in which the glucose molecule is well suited to its function in living organisms
Soluble- can easily dissolve in other substances e.g. in blood to be carried around the body
Easily broken down to release energy- especially important for animals since they are very mobile and require energy for respiration and movement
Cellulose is a carbohydrate. A student described the structure of cellulose as the following:
The cellulose molecule is insoluble
It contains only the elements carbon, oxygen and hydrogen.
It is made up of alpha glucose sub-units
The glucose sub-units are linked by 1-4 glycosidic bonds formed by hydrolysis reaction
It also has some 1-6 glycosidic bonds
It is made up of many long chains
The chains have branches
1) Identify 3 mistakes made by the student when describing the structure of cellulose
2) Suggest the name of a molecule that closely matches the students descriptions
1) - it is made up of beta glucose sub-units/ monomers
- The glucose sub-units are linked by 1-4 glycosidic bonds formed by a condensation reaction
- cellulose has no 1-6 glycosidic bonds as it is not branched
2) Amylopectin
Do question 2 in 2.1.2 Biological molecules exam practice booklet its on page 7, 8, 9, 10
Agarose forms part of a more complex carbohydrate called agar, which is used as a growth medium for bacteria. Bacteria cannot breakdown the agarose in agar. Suggest why bacteria cannot break down agarose.
Bacteria do not have the correct enzymes to digest agarose
Amino acids form part of the structure of proteins State the name given to the sequence of amino acids in a protein molecule
Primary structure
Is collagen fibrous or globular
Fibrous
Collagen is an important fibrous protein which forms a part of the wall of blood vessels. State one property of collagen that makes it a useful component of blood vessel walls.
Strong
Another protein that is important for mammals is haemoglobin. State one function of haemoglobin
Contains prosthetic haem group which binds to oxygen in the lungs and transports it around the body
Explains why glycogen makes a good storage molecule
It contains a lot of 1-6 glycosidic bond between chains of monosaccharides and 1-4 glycosidic bonds between alpha glucose monomers
This means a lot of glucose monomers can be stored in a small compact way, therefore provide more energy.
It has free ends so glucose can rapidly be hydrolyzed and used especially in animals as they are mobile and need energy for respiration
When glycogen is hydrolysed molecule A is produced. State the precise name of molecule A
Alpha glucose
State one function of alpha glucose
Provides energy when broken down by respiration
Cellulose is a carbohydrate molecule found in plants. Give the difference in structure between glycogen and cellulose.
Glycogen:
-no hydrogen bonding
-1-4 glycosidic bond between glucose monomers and 1-6 glycosidic bonds between branches
- alpha glucose monomers
-branched molecule
Cellulose:
-hydrogen bonding
-1-4 glycosidic bonds only
-beta glucose monomers
-not branched
Give 3 examples of lipid compounds that are important in living organisms
Triglycerides
Phospholipids
Cholestrol
Complete Question 5 part a in Biological molecules exam practice booklet
Describe how to do the emulsion test for lipids and how a positive result would be identified
-Add 1cm3 of sample in test tube
-Add 1cm3 of ethanol
-Add 1cm3 of water
Positive result= milky or cloudy emulsion forms
Two examples of lipid molecules are triglycerides and phospholipids. Identify 2 differences and 2 similarities in the structures of triglycerides and phospholipids
2 Similarities:
- both contain glycerol molecule
- both have fatty acid tails
2 Differences:
Triglyceride= 3 fatty acid tails
Phospholipid= 2 fatty acid tails
Triglyceride= no phosphate head
Phospholipid= contains phosphate head
It is possible to test for the presence of lipids in a food sample. Name the test used to identify the presence of lipids
Emulsion test
Describe how you would carry out an emulsion test on a food sample
1) Crush food with pestle and mortar
2) Filter it using filter paper and filter funnel
3)Add 1cm3 of sample
4) Add 1 cm3 of ethanol
5) Add sudan III stain
6) Add 1 cm3 of water
7) Shake thoroughly
Observe color change: positive result= sample turns milky or cloudy emulsion
Cholesterol is an important biological molecule. State 2 roles of cholesterol in living organisms.
1) Stores excess fat
2) Regulates fluidity in membranes e.g. phospholipid bilayer
Explain one way in which the molecular structure of cholesterol is similar to the molecular structure of a carbohydrate
Contains 6 membered ring
Water is a compound known as the universal solvent as it has the ability to dissolve many ionic and covalent compounds due to its polar nature. Which carbon compound will not form hydrogen bonds with water and therefore will not dissolve in water
Propane
Do question 9 and 10 on page 16 and 17 of biological molecules exam practice booklet
Do question 11and 1 on homework task on page 18 and 19 of biological molecules exam practice booklet
Do question 2 and 3 on homework task on page 20 and 21 of biological molecules exam practice booklet
The students are provided with 3 different fruit juices labelled A, B and C. The benedicts test was tested out on each fruit juice and samples were prepared for the colourimeter.
Explain how the students would use the calibration curve to estimate the glucose concentration of the fruit juices
Read along the percentage absorbance until they meet the line of the best fit and then read down to glucose concentration
A student wrote the following hypothesis. “The higher the concentration of glucose in the fruit juice, the sweeter it will be”
Describe how you would carry out a controlled experiment to test this hypothesis without using a colorimeter.
You could do the benedicts test
- Put 2 cm3 of each fruit juice sample in test tube then Add 2cm3 of Benedicts solution
-Heat in water bath for 2 minutes 85*C
-Observe color change, the darker red the sample is the more glucose is present
A student is using the Benedicts test without using a colourimeter to investigate the concentration of glucose in different fruit juices. State one way in which the results may differ from student to student.
Benedicts test will result in different colours of each sample of fruit juice e.g. dark red, yellow etc.
The test is subjective- different people might think of different colours e.g. one might say its orange while someone else says its red
State 2 ways in which the molecular structure of cholesterol is similar to the structure of glucose
-Both have a 6 carbon ring
-Both contain hydroxyl group
Glucose is an important biological molecule required by cells for cellular respiration. State the physical property of glucose that allows it to be easily transported in the blood stream.
It is soluble
Why is water described as a polar molecule
Because there is an uneven charge distribution across the molecule- a delta + region over the H+ atoms and a delta negative region over the O atom
Do question 2 on page 24 of Biological molecules exam practice booklet
Hydrogen bonds between 3 water molecules
Water is a universal solvent. Why is this important
Helps minerals dissolve in water so aquatic organisms can uptake minerals and nutrients easily
Water is cohesive. Why is this important
Allows long columns of water to rise up narrow tubes, e.g. in xylem so water can serve as a transport medium
It takes a lot of energy to raise the temperature of water. Why is this important.
It means water wont change state from liquid to gas, meaning Hydrogen bonds won’t break as easily. Therefore water stays cool in the summer and warm in the winter.
Ice is less dense than water. Why is this important.
Ice forms on the surface of lakes and insulates the water below so aquatic organisms do not freeze in the winter.
Water has some surface tension. Why is this important.
Allows small insects to use the surface of water e.g. pond skaters
Examine 2 properties of water which are just as important for eukaryotes as they are for prokaryotes.
High heat capacity- to survive extreme temperatures- they need stable temperature to be maintained
Universal indicator- uptake minerals easily- reactions can occur readily in aqueous solution
Fill in the blanks.
A monomer is a single _________molecule that can form covalent bonds with other similar monomers to form a large molecule called a ________. Monomers are joined together by _________ reactions. ________ bonds within polymers can be broken down by hydrolysis reactions.
A monomer is a single sugar molecule that can form covalent bonds with other similar monomers to form a large molecule called a polymer. Monomers are joined together by condensation reactions. Covalent bonds within polymers can be broken down by hydrolysis reactions.
The biological molecule Carbohydrate contains what elements
Carbon
Hydrogen
Oxygen
The biological molecule Nucleic Acid contains what elements
Carbon
Hydrogen
Phosphorous
Oxygen
What is a sugar which contains 6 carbons called
Hexose
What is a sugar which contains 5 carbons called
Pentose
Draw a structure of beta glucose and describe how it differs from alpha glucose
Page 26 Biomol booklet exam practice
Beta glucose has a hydroxyl group on top of main carbon ring whilst alpha glucose has Hydrogen on top of carbon ring
What forms when 2 alpha glucose monomers join together
Maltose
When alpha glucose and fructose join together what does that make
Sucrose is formed
Lactose is a disaccharide made up of what
Alpha glucose and galactose
Do the second set of questions on carbohydrates on page 26 of Biomols exam practice booklet
Name the bond that joins 2 monosaccharides together
Glycosidic Bond
Describe how polysaccharide can be broken down. Ensure you name the type of reaction and what is needed for it to occur.
Polysaccharides can be broken down by hydrolysis reactions whereby 1 water molecule is needed to break down each glycosidic bond
A triglyceride consists of 4 molecules joined together. What are the molecules
3 fatty acid chains or tails
A glycerol molecule
How does a phospholipid differ from a triglyceride
Phospholipid= contains a phosphate head
Triglyceride= No phosphate head
Phospholipid= 2 fatty acid tails
Triglyceride= 3 fatty acid tails
Phospholipid= forms only 2 ester bonds
Triglyceride= forms 3 ester bonds
Why are triglycerides described as macromolecules and not polymers
Because they are made up of large, complex molecules which are not built from repeating units of monomers
Fatty acids can be saturated or unsaturated. What is the difference between them.
What impact does this have on their structure
Saturated= full of ‘h’ bonds and has no C–C double bonds
Unsaturated= has at least 1 C–C double bond
Impact on structure:
Double bonds cause molecules to bend so they cannot pack as closely together. Unsaturated fats are liquid at room temperature, whereas saturated fats are solid
Show how a glycerol molecule can join together with 3 fatty acid tails to form a triglyceride.
Page 28 of Biological molecule exam practice booklet in second set of questions
What is the name of the bond between the fatty acids and glycerol molecule, and what type of reaction leads to the formation of this bond.
Ester bond- forms through a condensation reaction whereby 3 water molecules are formed and 3 ester bonds are formed
What is esterification
look at kerboodle text book and answer question
What reaction causes a triglyceride to break down into its constituent molecules and what is needed for this reaction to occur.
3 Hydrolysis reactions, break 3 ester bonds using 3 water molecules
Give 3 functions of triglyceride
-Insulation= heat+ electrical
-protection= around vital organs
-Buoyancy= for water dwelling animals to stay affloat
One function of Triglycerides is that they are an excellent energy storage, but Why
Because they contain 3 fatty acid tails– provides a lot of storage for energy, 2 x as much energy as equivalent carbohydrate
It’s insoluble so won’t affect water potential and no osmotic effect will occur
Fill in the blanks:
Phospholipids have a _________ phosphate head and hydrophobic ___________tails. This allows them to form _______ with the ___________ heads on the outside and the _____________ tails on the _________, so they play a key role in the formation of _____ ___________.
Phospholipids have a hydrophilic phosphate head and hydrophobic fatty acid tails. This allows them to form bilayers with the hydrophilic heads on the outside and the hydrophobic tails on the inside, so they play a key role in the formation of cell membranes.
Cholesterol plays an important role in cell membranes. Describe this role.
It regulates fluidity of membrane by making sure not all molecules are able to pass through. This ensure membrane stays fluid even when temperature drops and does not fall apart when temperature rises
Proteins are polymers made up of what
A sequence of amino acids joined together by peptide bonds
What type of reaction joins 2 amino acids together
condensation reaction links 2 amino acids together
What is the bond between 2 amino acids called
A peptide bond is formed between 2 amino acids
What type of reaction breaks the bond between 2 amino acids
Hydrolysis reaction breaks the peptide bond between 2 amino acids
Show how 2 amino acids can join together to make a dipeptide
Page 29 Biological molecules exam practice booklet last question on page
The primary structure of a protein is…
The primary structure of a protein is a sequence or chains of amino acids linked together by a peptide bond
Describe the 2 types of secondary structure which can occur in a protein
Alpha helix- coiled
Beta pleated sheets- folded
What holds the secondary structure of a protein together
Hydrogen bonds
The tertiary structure of a protein is…
the overall 3d shape of the protein
What type of bonds or interactions take place in the tertiary structure
Disulphide bonds
Ionic interactions
Hydrogen bonds
Hydrophobic bonds
Describe the strength of a Disulphide bond
very strong covalent bonds between 2 sulphur atoms
Describe the strength of an ionic interaction
Stronger than hydrogen bonds but still weak
Describe the strength of hydrogen bonds
Weak alone but collectively very strong and provides stability
Describe the strength of hydrophobic bonds
Weak interactions
Give 4 properties of globular proteins
- spherical
-functional
-water soluble
-compact
1 a)Describe why globular proteins are soluble
1b) How does this help them to carry out their function
2) Give an example other than haemoglobin
1a)Water molecules can interact with hydrophilic R groups on the outside of protein
1b) Can carry out metabollic reactions in aqueous environment
2) Enzymes, Antibodies
State whether the following statements are true or false:
- Haemoglobin has a quaternary structure
- Haemoglobin does not have a prosthetic group
- Haemoglobin is a simple protein
- True
- False it contains prosthetic haem group
- False
Describe what is a conjugated protein
Has a permanent non- component group called the R group
Why is haemoglobin described as a conjugated protein
Because it contains Fe3+ ions in the haem group and has 4 haem groups as part of its quaternary structure
Describe how the following features assist the globular protein insulin to carry out its function
- Soluble
- Very specific 3D shape
- Has to be soluble to target cells so needs to be carried in the blood
2) Has to bind to receptors in target cells therefore overall 3D structure is very important
Enzymes are also globular proteins. Why is it important that enzymes have a very specific 3D shape.
Give an example of an enzyme
Because they need specific active site to fit substrate in so the reaction can occur
Amylase
Compare:
Globular VS Fibrous
Solubility
Shape
Function
Solubility:
Globular= soluble
Fibrous= insoluble
Shape:
Globular= Spherical+ compact
Fibrous= Long+ thin
Function:
Globular= Metabollic processes
Fibrous= Structural
Collagen is found in…
bones, cartilage and tendons
Keratin is found in…
hair, nails, claws and hooves
Elastin is found in…
blood vessels and the lungs
Complete the statement:
To test for the presence of starch, we add a few drops of ______ solution. If starch is present it will go a ___________ color
To test for the presence of starch, we add a few drops of iodine solution. If starch is present it will go a blue or black color
A student is given 2 sugar solutions. How can she or he distinguish whether each one is a reducing or non-reducing sugar
- Add benedicts solution to 2 samples and gently heat until 85* C for 5 minutes
- If orange or red precipitate formed= reducing sugar
- If no precipitate then take sample and add HCl and boil
- Add NaOH powder to neutralize
- Add benedicts solution and heat
- Orange+ Red precipitate= presence of non-reducing sugar
Name the reagent used to test for the presence of protein. What color is positive results for proteins
Biuret solution
Protein is present= lilac or purple
Describe how you would carry out the emulsion test. What does this test for the presence of
- Add 1cm3 of sample to test tube
-Add 1cm3 of ethanol
-Add 1cm3 of water
-Shake thoroughly - Observe color change
-Milky emulsion= presence of lipids
Describe how you would determine the concentration of glucose in a test solution using a colorimeter
- Prepare serial dilutions of glucose
- Add equivalent volume of Benedicts test to serial dilutions- heat to above 80*C
- Pour off precipitate into cuvette and using blue filter measure absorbance of each concentration
- Plot absorbance against glucose conc.- plot line of best fit
- Take unknown sample react with Benedicts test and heat
- Measure absorbance and read off concentration of glucose at this value on graph.
How do biosensors work
Biosensors work by converting a biological response into an electrical signal
Give 2 uses of biosensors
- measuring blood glucose levels
-measuring contaminants in water
Fill in the blanks.
Chromatography is a technique used to ________ the components in a _______. The stationary phase can be __________ or a ___________________ plate. The mobile phase is the __________ that carries the biological molecules. An example of a solvent is _____ or ___________. Chromatography is used to work out the levels of any contaminants in drugs and food, and to test for drugs in the urine of athletes.
Chromatography is a technique used to separate the components in a mixture. The stationary phase can be chromatogram or a thin layer chromatogram plate. The mobile phase is the solvent that carries the biological molecules. An example of a solvent is water or ethanol. Chromatography is used to work out the levels of any contaminants in drugs and food, and to test for drugs in the urine of athletes.
What are Rf values
Rf values= distance travelled by solute /distance travelled by solvent
Describe how you could separate a mixture of amino acids using thin layer chromatography.
- Wear eye protection+ gloves
- Draw pencil line 2cm from bottom of plate and put dot where mixture will be added
- Spot mixtures of amino acids on dot. Allow to dry+ repeat
- Lower TLC plate into solvent- make sure solvent doesn’t rise above pencil
- Take out TLC when solvent has almost reached to the top of page
- Allow plate to dry + spray with ninhydrin
- Circle amino acid then work out Rf value
What is the monomer, polymer and bond of carbohydrates
Monomer= Monosaccharide
Polymer= Polysaccharide
Bond= Glycosidic bond
What is the monomer, polymer and bond for proteins
Monomer= Amino acids
Polymer= Polypeptides
Bond= Peptide
True or False
Starch is a structural polysaccharide
False
True or False
Cellulose contains Beta glucose
True
True or False
Glycogen is found in plant and animal cells
False
True or False
Storage carbohydrates must be soluble in water
False
True or False
Amylopectin is a branched polysaccharide
True
True or False
Starch turns blue/black in the presence of Benedicts reagent
False
True or False
Polysaccharides are formed by a series of condensation reactions between monosaccharides
Truey
A triglyceride is made up of…
3 fatty acids and a glycerol molecule
Proteins consist of long chains of…
Amino acids
The reaction which joins smaller molecules to form larger molecules is…
Condensation reaction
The reaction which breaks down large molecules to make smaller molecules is…
Hydrolysis reaction
Globular proteins are….
Compact and soluble
Fibrous proteins are…
insoluble and strong
Primary structure refers to…
the sequence and order of amino acids
Quaternary structure refers to…
several polypeptide chains joined together to form a functional protein
Tertiary structure refers to…
the overall 3D shape of a polypeptide
Secondary structure refers to…
the coiling or folding of the polypeptide chain, held together by Hydrogen bonds
Name the reagents used to test for the following biological molecules:
Protein
Starch
Reducing sugar
Lipid
Protein= Biuret solution
Starch= iodine solution
Reducing sugar= Benedicts solution
Lipid= Emulsion test- ethanol
On page 34 do PAG 9 chemical test Question in biological molecules exam practice booklet
The presence of reducing sugar is sometimes measured using reagent test strips. What are these.
These test strips contain a reagent which interacts with the reducing sugar. When immersed in the test sample, the reagent in the test strip will change colour if the reducing sugar is present.
What are Biosensors
Biosensors are devices that analyse the concentration of substances in a solution.
Scientists say the Benedicts test is semi quantitative. Why
When using benedicts test, the colour produced gives us a very approximate idea of the level of reducing sugar present e.g. brick red color shows greater level of reducing sugar than a green colour.
It’s semi quantitative because the Benedicts test only gives us an approximate idea of the level of reducing sugar present.
What causes the blue color of the Benedicts reagent?
Blue colour caused by the presence of Copper ion= Cu 2+
What happens to the Cu 2+ ions when they react with reducing sugar
An electron/ electrons are donated to Copper
What is the red precipitate made of
Testing for reducing sugars
Reducing sugar glucose donates a electron to Cu2+ ion making it a Cu+ ion which makes the red percipitate
What would happen if we left our test tubes for a couple of hours
Reducing sugar
The red precipitate will settle on the bottom of the test tube and the Benedicts solution will be on top
The benedicts solution that is left after the precipitate has settled will be less blue than before the reaction. Explain Why
Because some of the Cu 2+ ions have reacted and are no longer in solution
What would happen to the color of the benedicts solution if we did the test again with a higher concentration of glucose and why.
The benedicts solution will appear even less blue at the end as fewer Cu 2+ ions would remain in solution
What is the relationship between the concentration of the glucose solution and the blueness of the Benedicts solution left at the end.
With the Benedicts test the greater the concentration of glucose the less blue the Benedicts solution will be at the end.
What ‘q’ does the colorimeter allow us to do
We quantify the blueness of the solution by using a machine called the colrimeter
What happens to all of the colours except blue if we shine white light through Benedict’s solution
All of the colours in white light will be absorbed except blue- because benedicts solution allows blue light to pass through, thats why Benedicts solution has a blue color
What can absorption of light be used to do
Glucose concentration
The absorption of light can be used to quantify the level of blueness
What is the best wavelength (color) of light to use to quantify the level of absorbance and why.
Red because Benedicts solution absorbs red the most out of all the different colors as red is on the opposite side of the spectrum to blue
What ‘c’ word is used to describe the relationship between blue and red colours
Red is complimentary color to blue
What color filter do we use in front of the lamp and why
Colorimeter and reducing sugars
Red filter infront of lamp- red filter only allows red to pass through
What happens to the amount of red light absorbed when the solution is less blue than before
Because the solution is less blue( as it has reacted with glucose and has lost some of its blue color) than before, less of the red light will now be absorbed
What is the relationship between the concentration of glucose in a solution, the blueness after reacting with Benedicts and the absorbance of red light.
The less red the light absorbed is the greater the amount of glucose that must have reacted with our benedicts solution By using the benedicts test with a colorimeter we can more accurately determine the concentration of glucose in a sample
What is a qualitative test in Biology
Collects categoric data
e.g. presence or absence of a particular BioMol
What is quantitative data in Biology
Collects numerical data
- concentration or volume of a BioMol in solution
In the Module 2:Foundations in Biology
2.1.2 Biological Molecules practical bboklet given out by Emma, complete the bottom of page 2
What is the name of the small plastic container we transfer our solutions to so we can measure abosrbance in colorimeter
Cuvette
What is a reagent
A reagent is a chemical that can help to identify the biological molecules present in a solution. It will react with a particular biological molecule or a group of biomoles in a characteristic way, often producing a color change
What do you need to remember about how to position the cuvette in the colorimeter
They have 2 transparent sides and 2 sides that are translucent. We place it so that light passes through the transparent sides.
Why do we use a red filter in colorimeter
Red is complimentary color to blue, red will be the colour most absorbed by the blue solution
What do we set the colorimeter to measure
Absorption- how much red light is absorbed by solution
What is the purpose of the cuvette containing just distilled water
We tell the colorimeter to consider the distilled water to absorb zero red light
Describe how we use the calibration curve to find the concentration of glucose in our unknown sample
Use the absorbance and draw a horizontal line across until it meets the line of best fit and then draw a line vertically down to glucose concentration
What can we do if the absorbance of our unknown solution is too high to read off our calibration curve
Then you need to dilute the solution and read the concentration again
Why is using a Benedicts test with a colorimeter good
By using the Benedicts test with a colorimeter we can more accurately determine the concentration of glucose in a sample
What does the colorimeter not tell us
The actual concentration of glucose which is why we prepare a whole range of known glucose concentrations
Do pages 22 and 23 2.1.2 Biological molecules testing for Biological molecules- booklet given out by Emma
Do pages 24 and 27 2.1.2 Biological molecules testing for Biological molecules- booklet given out by Emma
How do you test for the presence of Starch?
Add Iodine solution
Give me a procedure to test for starch
- Pipette 2cm3 of your sample into a test tube.
- Add a few drops of Iodine solution
- Observe colour change
Positive result= blue/black
Negative result= remain orange
How do you test for Lipids
By doing the emulsion test
Give me the procedure for testing for lipids
- Add 1cm3 of ethanol to a test tube
- Add 1cm3 of sample
- Shake vigorously to dissolve
- Add 1cm3 of cold water
- Observe colour change
Positive result= milky emulsion
Negative result= lack of complex/ change in colour
What is the test for proteins
Biuret test
Give me a procedure to test for Proteins
- Add 2cm3 of sample solution to test tube
- Add 2cm3 of Biuret solution
Positive result= purple/lilac
Negative result= sample/solution remains light blue colour
How do you test for reducing sugars?
Benedicts test
Give me a procedure for the Benedicts test
- Pipette 2cm3 of your sample into a test tube
- Add a 2cm3 of Benedict’s reagent
- Heat at 85*c for 5 minutes in a water bath
- Record the colour change
Positive result= brick red, orange, yellow
Negative result = blue or green
How do you test for non-reducing sugars?
Benedicts reagent
Why is Benedict’s reagent used for non-reducing sugars?
Used on any suspected sugar that is negative for reducing sugars e.g. sucrose
Give me a list of reducing sugars
Glucose, fructose, lactose, maltose, galactose
Give me a list of non-reducing sugars
Sucrose
Give me a procedure for Benedict’s test for non-reducing sugars
- Pipette 2cm3 of your sample into a test tube
- Add 1cm3 of 1M HCl
- Heat for 2 minutes in a water bath at 85*c
- Neutralise with Sodium hydrogen carbonate powder (NaHCO3), checking pH with Indicator paper
- Add 2cm3 of Benedict’s reagent
- Heat at 85* c for 5 minutes
Positive result= same as Reducing sugars
negative result= solution Remains blue
What is a qualitative test?
Collects categoric data
e.g. presence or absence of a particular BioMol
What is a quantitative test?
Collects numerical data
e.g. concentration/ volume of a BioMol in a solution
Define Reagent
Chemical that helps identify BioMol present in solution, by reacting with the BioMol in a characteristic way, often producing a colour change
Make flashcards on pages 18 and 19 in 2.1.2 Biological molecules testing for Biological molecules- booklet given out by Emma
