Unit 1.1 Biological compounds Flashcards
What do all organisms need for survival
(b) What is it often called
All organisms need inorganic ions to survive
(b) These inorganic ions are often called
minerals.
Where do inorganic ions occur?
They occur in a solution in the cytoplasm and body fluid of organisms, some in high concentrations and others in very low concentrations
What are micronutrients and give 2 examples
Micronutrients are minerals needed in minute (trace) concentrations e.g. copper and zinc.
What are Macronutrients and give 2 examples
Macronutrients are needed in small concentrations e.g. magnesium and iron.
Name the four key inorganic ions in living organisms
Magnesium ions (Mg2+) Iron ions ( Fe2+) Calcium ions (Ca2+) Phosphate ions (PO4 3-)
What is the biological role for Magnesium in plants
Constituent of chlorophyll and therefore essential for photosynthesis
What is the biological role for Iron in animals
Constituent of haemoglobin, which transports oxygen in red blood cells
What is the biological role for Nitrate
Nitrogen derived from nitrate is needed for making nucleotides, including ATP, DNA and RNA. Nitrogen is also needed for amino acid formation.
What is the biological role for Phosphate in living organisms
Used for making nucleotides, including ATP, DNA and RNA. A constituent of phospholipids found in biological membranes. Hardens bones.
What is the biological role for Calcium in living organisms
Hardens bones and teeth (not strengthen). Also a component of plant cell walls.
What does the term ‘organic’ mean
Molecules that have a high proportion of carbon and hydrogen atoms
What does the term ‘inorganic’ mean
A molecule or ion that has no more than one carbon atom.
Why is water a polar molecule?
Due to the uneven distribution of charge within the molecule - The oxygen end of the molecule is more electronegative than the Hydrogen and the Hydrogen atoms have a positive charge.
What is a dipole
A polar molecule which has a positive and negative charge, separated by a very small distance - uneven distribution of charge
When two water molecules are in close contact, what do the opposing charges do and what do they form?
When two water molecules are in close contact the opposing charges attract each other forming a hydrogen bond.
What does the term ‘Hydrogen bond’ mean
The weak attractive force between a hydrogen atom (with a partial positive charge) and an atom with a partial negative charge, usually oxygen or nitrogen.
Are individual hydrogen bonds weak and what happens when there are many hydrogen bonds (between many water molecules)
Individual hydrogen bonds are weak, but many hydrogen bonds (between many water molecules) form a lattice-like framework which is much stronger.
What is cohesion?
A property of water molecules that creates an attraction between them and causes them to stick together
Name 8 properties of water
1 - Water is a solvent
2 - Water as a transport medium
3 - Chemical reactions take place in water
4 - Water has a high specific heat capacity
5 - Water has a high latent heat of vaporisation
6 - Cohesion
7 - Surface tension
8 - Density
Can ions and other polar molecules dissolve in water?
Yes
Can non-polar molecules such as lipids dissolve in water?
No
Why is water’s high specific heat capacity important for organisms?
Water acts as a temperature buffer, enabling endotherms to resist fluctuations in core temperature and to maintain optimum enzyme activity.
Why is water’s high high latent heat of vaporisation important for organisms?
When water evaporates, it has a cooling effect. This is important in homeostasis; organisms can lose heat though sweating or panting
What does evaporation of water from a surface cause?
Cooling
Why is water an important solvent for organisms?
Water is a polar universal solvent. It enables chemical reactions to take place within cells. the transport of materials in the plasma and the removal of metabolic waste
Why does water have a high surface tension?
Due to the ordered arrangement and cohesion of molecules at the surface of water
Why is high surface tension of water important for organisms? x2
- Enables the transport of water and nutrients through plants stems and small blood vessels in the body
- Allows small insects to ‘walk’ on water
Due to cohesion between water molecules what is need to change water from a liquid to a vapour state?
A large amount of heat energy is needed
What temperature does water have its maximum density?
4 degrees Celcius
How does ice float on water and what does it do to the water beneath it?
b) What does this reduce the tendency of?
Ice is less dense than water and therefore floats on the surface and insulates the water beneath it
b) This reduces the tendency for large bodies of water to freeze completely allowing organisms to survive.
What are carbohydrates?
Carbohydrates are organic compounds which contain the atoms carbon, hydrogen and oxygen. They are long chains of sugar called saccharides
What are the 3 types of saccharides?
Monosaccharides, disaccharides and polysaccharides
What do two monosaccharides form?
Disaccharide
What do many monosaccharide molecules form?
Polysaccharide
What are monosaccharides?
Monosaccharides are small organic molecules used as building blocks of complex carbohydrates
Give 2 features of a monosaccharide
Sweet and soluble
What is the general formula for monosaccharides?
(CH2O)n
How can monosaccharides be grouped?
Be grouped according to the number of carbon atoms they have.
How many carbon atoms does a triose have?
A triose sugar has three carbon atoms,
How many carbon atoms does a pentose have?
A pentose sugar has five carbon atoms
How many carbon atoms does a hexose have?
A hexose sugar has six carbon atoms.
What is glyceraldehyde?
A triose used in metabolic reactions
What is a ribose?
A pentose sugar which is a component of nucleic acid
What is glucose?
b) What is it the main substrate for?
c) How many isomers does it have and what are they?
Glucose is a monosaccharide containing 6 carbon atoms in each molecule.
b) It is the main substrate for respiration therefore it has great importance
c) It has 2 isomers - alpha and beta glucose
What is the function of triose?
Important in metabolism. Triose sugars are intermediates in the reactions of respiration of respiration and photosynthesis
What is the function of pentose?
Pentose is constituents of nucleotides e.g. deoxyribose in DNA, ribose in RNA, ATP and ADP
What is the function of hexose?
a) Source of energy in what?
b) Which bonds are broken to release energy and later transferred to make what?
Glucose is a hexose sugar.
a) Glucose is a source of energy in respiration.
b) Carbon-hydrogen and carbon-carbon bonds are broken to release energy, which is transferred to make adenosine triphosphate (ATP).
What is the name of the bond formed when 2 monosaccharides react?
b) What type of reaction is it?
Glycosidic bond
b) A condensation reaction
What are disaccharides?
Disaccharides are composed of two monosaccharide sub-units bonded with the formation of a glycosidic bond and the elimination of water. This is an example of a condensation reaction.
What is Maltose and how is it formed?
b) What is its biological role?
Maltose is a disaccharide formed by the condensation of 2 glucose molecules
b) In germinating seeds
What is Sucrose and how it it formed?
b) What is its biological role?
Sucrose is a disaccharide formed by the condensation of glucose and fructose
b) A product of photosynthesis which is transported in the phloem
What is Lactose and how it it formed?
b) What is its biological role?
Lactose is a disaccharide formed by the condensation of glucose and galactose
b) Found in mammalian milk
How can a glycosidic bond be broken?
By hydrolysis
What is Benedict’s reagent used to test?
b) What is needed for this reaction?
Used to test for reducing sugars
b) Heat (80 degrees celcius or above)
What do reducing sugars reduce and form?
Reduce blue copper ll sulphate forming copper 1 sulphate
What must Sucrose be firstly done by boiling in what
b) What 2x things are formed?
c) What must be done to the acid and with what?
Sucrose must first be hydrolysed by boiling in dilute hydrochloric acid. Glucose and fructose are formed. The acid must be neutralised with dilute sodium hydroxide before testing with Benedict’s reagent.
For the testing of reducing sugars, when glucose and fructose are formed, what do they donate and what do they reduce?
b) What does this form?
Glucose and fructose are reducing sugars
which readily donate an electron to reduce copper II sulphate
b) This forms the brick-red precipitate copper I sulphate.
What is a polysaccharide?
What are the formed from?, What are they linked by and how was the link formed?
Polysaccharides are large complex polymers. They are formed from very large numbers of identical monosaccharide units, which are their monomers, linked by glycosidic bonds formed by condensation reaction.
What does the term ‘polymer’
A large molecule comprising of repeated, identical units (monomers) bonding together.
Give 4 examples of polysaccharides
Starch
Glucose
Cellulose
Chitin
What monosaccharide does starch allow plants to store
Glucose
What is starch made up of?
Starch is made up of α glucose monomers, added one at a time by condensation reaction.
What is the function of starch
Energy storage in plants
What are the 2 types of polysaccharides for starch?
Amylose and amylopectin
What is amylose?
Amylose is an unbranched chain of glucose molecules joined by 1, 4 glycosidic bonds as a result of that amylose is coiled and thus it is a very compact molecule meaning it can store a lot of energy.
Describe the structure of starch x4
- Polymer of a-glucose monomers
- Two forms: amylose and amylopectin
- Amylose: a-1, 4-glycosidic bonds, unbranched
- Amylopectin: a-1, 4- and a-1, 6-glycosidic bonds, branched
Does starch have an osmotic effect on the cell; does it affect the water potential of the cell?
No
What type of saccharide is amylose and give 2 features of it
Amylose is a polysaccharide component of starch. It is unbranched and coiled
What type of saccharide is amylopectin and what is each branch point formed by?
Amylopectin is a polysaccharide component of starch. Each branch point is formed by a C1 – C6 glycosidic bond.
What is the function of glycogen?
Energy storage in animals
In glycogen, what are the a glucose molecules joint by?
C1 - C4 and C1- C6 glycosdic bonds
How does the structure o glycogen relate to its function?
It is highly branched enabling the rapid hydrolysis of glucose molecules
Are both starch and glycogen easily hydrolysed to alpha glucose ?
Yes
Where is cellulose found?
Plant cell walls
Describe the structure and function of cellulose x3
- Linear polysaccharide that is the main component of the cell wall in plants
- Consists of many Beta glucose molecules joined by B-1,4-glycosidic bonds
- Alternate glucose molecules rotated 180 degrees allowing hydrogen bonds between parallel chains, forming myofibrils
Why are microfibrils bunched together?
To form fibres
Give 3 features of cellulose
It is unreactive and stable (due to being unbranched) and has a high tensile strength (due to the formation of microfibrils and fibres)
What is Chitin
Chitin is a linear polysaccharide that is made up of beta glucose molecules with amino acid side chains
Describe the structure and function of chitin
x3
- Linear polysaccharide found in exoskeletons of arthropods, such as insets, and fungal cell walls
- Consists of Beta-glucose molecules linked by C1 - C4 glycosidic molecules
- Alternate glucose molecules are rotated by 180 degrees, this allows hydrogen bonds to form between the OH groups of adjacent chitins in chains. The cross-linked parallel chains form microfibrils.
Give 3 features of Chitin
Strong, waterproof and lightweight
What are lipids?
Lipids are biological molecules which are only soluble in organic solvents such as alcoholics
What are the 2 types of lipids?
Saturated and unsaturated
What are the 3 atoms lipids contain
Carbon, hydrogen and oxygen
What is the most common type of lipid
Triglycerides
Explain how a triglyceride is formed
One molecule of glycerol forms ester bonds with 3 fatty acids via condensation reactions
What is glycerol?
A type of alcohol
Relate the structure of triglycerides to their functions x4
- High energy-to-mass ratio - energy storage, high calorific value of oxidation
- Insoluble hydrocarbon chain - no effect on water potential of cells, used for waterproofing
Slow conductor of heat - thermal insulation e.g. adipose tissue
Less dense than water - buoyancy to aquatic animals
What is an ester bond?
A bond between a fatty acid chain and glycerol in a condensation reaction
How many esters bonds do triglycerides have?
3
What is the difference between saturated and unsaturated fats?
Saturated fats have no double bonds between the carbon atoms and are solid at room temp due to strong intermolecular forces
Unsaturated fats have one or more double bonds between the carbon atoms in the hydrocarbon chain and are liquid at room temp due to weak intermolecular forces
Differentiate between monounsaturated and polyunsaturated fatty acids
Monounsaturated fatty acids contain one double bond between the carbon atoms
Polyunsaturated means there are 2 or more bond between the carbon atoms
Give an example of what tends to be saturated
b) where can saturated lipids be found?
Animal lipids
b) Animal fats
Give an example of what tends to be unsaturated
b) where can unsaturated lipids be found?
Oils
b) Plants
What are triglycerides used for?
Energy reserves in plant and animal cells
What are thee 2 main causes of heart disease?
Fatty deposits in the coronary arteries (atherosclerosis) and high blood pressure (hypertension)
What can a diet containing too much saturated fat increase?
Increase cholesterol levels in blood thus increasing the risk of coronary heart disease
How are lipoproteins formed?
When lipids and proteins combine
What is LDL
Low density lipoprotein
If the diet is high in saturated fats, LDL build up. What happens after this? x3
Fatty material called atheroma is deposited in the coronary arteries, restricting blood flow and, therefore, oxygen delivery to the heart tissue.
This restricted blood flow can result in angina.
If the coronary arteries become completely blocked a myocardial infarction or heart attack occurs.
What is HDL
High density lipoproteins
If the diet is high in unsaturated fats, the body makes more HDL. What does this do? x2
Carry harmful fats to the liver for disposal.
The higher the ratio of HDL:LDL in a person’s blood, the lower the risk of cardiovascular and coronary heart disease.
How do LDLs contribute to the risk of cardiovascular disease?
The high blood cholesterol level caused by LDLs lead to formation of atherosclerosis plaques
What is a phospholipid?
A type of lipid formed by the condensation of one molecule of glycerol, 2 molecules of fatty acid and a phosphate group
What type of heads and tails do phospholipids have?
Phospholipids have hydrophilic heads and two hydrophobic fatty acid tails.
What is a micelle?
A fatty droplet
What is a bilayers
Double layer
What does the phospholipid bilayer form?
The basis of all cell membranes
Why do phospholipids from micelles when they are in contact with water?
As heads are on the outside as they are attracted to water and tails are on the inside as they move away from water.
Compare triglycerides and phospholipids
(How many fatty acid tails)
(Group)
(Polar or not)
Triglycerides - 3 fatty acid tails, No phosphate group and non polar (completely hydrophobic)
Phospholipids - 2 fatty acid tails, Phosphate group and Polar head is hydrophilic, fatty acid tails are hydrophobic
How can we determine whether a substance contains lipid?
What would happen if lipid is present?
it is mixed thoroughly with absolute
ethanol; any lipid present in the sample will dissolve in the ethanol.
Are lipids insoluble or soluble in water?
Insoluble
What happens when lipids is mixed water
Form tiny droplets called an emulsion. The emulsion is cloudy white and indicates lipids are present
Give the 9 functions of lipids
- Energy reserve (store) in plants and animals
- Thermal insulator
- Protection
- Metabolic water source
- Waterproofing
- Low density and buoyancy
- Nerve transmission
- Steroids and cholesterol
- Cell membrane formation
How do proteins differ from carbohydrates and lipids?
in addition to carbon, hydrogen
and oxygen atoms, they also always contain nitrogen atoms. Many proteins also contain sulphur and phosphorus atoms too.
What is a protein
A large molecule synthesized from amino acid monomers
What is the term used for a chain of amino acids
polypeptide
How many different amino acids are there?
20
Describe the general structure of an amino acid
An amino group (-NH2), which is basic or alkaline.
A carboxyl group (-COOH), which is acidic.
A hydrogen atom.
The R-group, which is a variable group of atoms.
How does a dipeptide and polypeptide differ?
A dipeptide contains 2 amino acids and polypeptides contain 3 or more amino acids
How many different R groups are there in an amino acid?
20
What is the simplest amino acid which has a hydrogen atom as its R-Group called?
Glycine
What is the structure of proteins determined by? x3
The order and number of amino acids, bonding present and the shape of the protein
How are polypeptides formed?
Main amino acid monomers join together in condensation reactions, forming peptide bonds (-CONH-)
What is the difference between essential and non-essential amino acids?
Essential amino acids cannot be
synthesised by our bodies, and must be provided by our diet. Non-essential amino acids can be synthesised by our bodies.
What are the 4 levels for the protein structure?
Primary
Secondary
Tertiary
Quaternary
Describe the Primary structure
The primary structure is the sequence of amino acids in a polypeptide chain. The sequence of amino acids is determined by DNA; one gene codes for one polypeptide. The bond between each amino acid is a peptide bond.
Describe the Secondary structure
The secondary structure is the shape that the polypeptide chain forms due to hydrogen bonding. Hydrogen bonds twist and fold the polypeptide forming an alpha helix or a less common beta pleated sheet.
Describe the Tertiary structure
The alpha helix of a secondary protein structure is further folded and twisted to give a more complex, compact 3D
structure. The shape is maintained by disulphide, ionic, covalent hydrophobic and hydrogen bonds. Enzymes have a tertiary protein structure. The bonds
maintain the shape of the enzyme’s active site.
Describe the Quaternary structure
The quaternary structure arises from a combination of two or more polypeptide chains in tertiary form. These are associated with non-protein groups and form large complex molecules such as haemoglobin. Haemoglobin has four polypeptide chains. Four genes are needed to code for haemoglobin; one gene for each polypeptide.
What type of protein is haemoglobin?
A water soluble globular protein
Describe how the structure of fibrous protein relates to their function x3
- Long peptide chains, folded in parallel
- Little tertiary/quaternary structure aside from cross-linkages for strength
- This makes them insoluble and good for structural roles
What is the difference between a reducing and non-reducing sugar?
A reducing sugar has a free aldehyde or ketone functional group where as a non-reducing sugar doesn’t
Describe the Benedict’s test for non0reducing sugars (6 steps)
1 - Negative test for reducing sugar
2 - Hydrolyse non-reducing sugars with an equal volume of dilute HCL
3 - Heat in a boiling water for 5 minutes
4 - Add NaHCO3 to neutralize the acid
5 - Re-test resulting solution with Benedict’s reagent
6 - Observe the colour of the precipitate formed
Name the food test used to identify proteins?
Biuret test
Describe the Biuret test - 3 steps
1 - Add an equal volume of the sample to be tested and NaOH
2 - Add a few drops of dilute copper (II) Sulphate solution
3 - Mix gently and record any observations
Describe the positive result of a biuret test
Colour change from pale blue to purple
Describe the emulsion test for fats and oils - 4 steps
Add ethanol to the sample and shake
Allow the mixture to settle
Add and equal volume of water
Record any observations
What type of structure does the enzyme lysozyme have?
a tertiary structure
How can Proteins be classified?
Into globular and fibrous proteins
Name some of the globular protein functions
Globular proteins have functions such as enzymes, antibodies and hormones. Globular proteins are compact and
folded into 3D spherical molecules. They are soluble in water
Name 3 features of fibrous proteins
Insoluble in water, tough and strong
What does a a single fibre consists of?
Three identical polypeptide chains twisted together like a rope
Compare Hemoglobin and Collagen polypeptide molecules Same or different association Highest level of protein structure
Haemoglobin - 4 polypeptide molecules, each polypeptide molecule is different (4
genes are needed to code for haemoglobin), haemoglobin is associated with non-protein groups (haem groups) and the highest level of protein structure is quaternary
Collagen - 3 polypeptide molecules, each polypeptide is the same (only one gene is needed to code for collagen), collagen is not associated with non-protein groups and the highest level of protein structure is secondary
What is a fibrous protein
A class of long chain proteins that are generally insoluble in water and have typically have structural roles
What is a globular protein
A class of spherical shaped proteins that are generally water soluble and typically have metabolic structures
Why is Collagen a fibrous protein?
Due to the presence of hydrogen and covalent bonds in the structure
