Biological Molecules (from Book) Flashcards
Carbohydrates are respiratory substrate what else do they do
What role do they play in cell wall
They release the energy required to carry out functions
There are structural role in the cell wall they form part of the glycoproteins and glycolipids
Lipids
A major component of plasma membranes
Make certain hormones
Act as respiratory substrate
Proteins
Diverse – structure/function
Found in plasma membranes
Most important rollers in enzymes
Carry the chemical messages within/between cells
Nucleic acid
e.g. DNA
Carries genetic information that determines the structure of proteins
or RNA synthesise proteins
When is glucose produced by plants
During photosynthesis it is converted into insoluble starch for storage
During aerobic respiration chemical reactions occur what do they use
Glucose +oxygen to release energy
In plants and algae what is used to produce fat for storage + cellulase
Glucose is used to produce fat for storage which strengthens the cell wall and produces proteins
Protein molecules are made up of long chains of what
Amino acids
What makes Protein molecules shape unique
Protein molecules are made up of long chains of amino acids that can fold to produce specific shapes to enable other molecules to fit into the protein
Proteins active structural components of tissues such as
Muscles, hormones, antibodies, catalysts
What do catalysts do
Increase the rate of chemical reactions
Biological catalysts are proteins called enzymes
The shape of an enzyme is vital for its function what can change the shape of an enzyme
High temperatures
PH values
The definition of molecular biology
The study of biological molecules which are part of particular groups of chemicals found in living organisms
What is covalent bonding
Chemical bonds were two atoms share electrons in the outer shell this creates a more stable compound called a molecule because the outer shell both atoms are filled and therefore more stable
What is ionic bonding
Is a weaker bond than covalent bonding
Ions with opposite charges attract one another the ➡️ electrostatic attraction is the ionic bond
E.g. Sodium chloride + chloride ion = sodium chloride
what is hydrogen bonding
Hydrogen bond is weaker than covalent or ionic bonding
Result in the electrons in the molecule not evenly distributed
Therefore electron spend more time at one position creating a polarised molecule
What is a polarised molecule
When the molecule is either more negative or positive because of its electrons
What is a weak electrostatic bond
This occurs when the negative region of a polarised molecule attracts the positive region of another polarised molecule
This bond is very weak individually but the collective force can alter the physical properties of the molecule (especially true for water)
What are some examples of industrially produced polymers and naturally produced polymers
Industrially produced = polyester, polythene
Naturally produced = polysaccharides, polypeptides, polynucleotide
What a polymer is from naturally what is formed each time a new sub unit is attached
A molecule of water (this is called condensation reaction)
What are polypeptides formed from
Amino acids
What are polysaccharides of starch formed from
Monosaccharides of glucose
Polymers can be broken down by adding water what is this process called
Hydrolysis – water molecules break the bond that link the subunits of the polymer
E.g. polypeptides can be hydrolysis back into amino acids
Amino acids can become
Polypeptides
Nucleotides can become
Polynucleotide
monosaccharides can become
Polysaccharides
Fatty acids and glycerol can become
Lipids
What is metabolism
All the chemical processes that take place in a living organism
A mole is the S1 unit of measuring the amount of substance. One mole = the same number of particles as there are in?
1 mole = The same number of particles as there are in 12 g of carbon 12 atoms
What is the avogado number/avogado constant
6.022 X10 to the power of 23
What is an atom
The smallest unit of chemical element that can exist independently
Nucleus = protons + neutrons
Electrons surround the outside
Neutrons
Protons
Electrons
Hydrogen
Neutrons = no electrical charge, say mass of protons, occur in nucleus
Protons = have a positive electrical charge
Electrons = orbit the shell of the nucleus, very small mass, negatively charged, their number determines the chemical properties of the atom
Hydrogen = only atom with no neutrons
What is the atomic number
The number of protons in an atom
What is the mass number
The total number of protons and neutrons in an atom
How do you determine what the overall charge is of an atom
The number of protons + electrons = 0
What is an isotope
The number of protons in an element always stays the same – number of neutrons can vary
Same chemical properties but different masses - useful for tracing biological processes e.g. fossil dating
What is an ion
Ion = if an atom loses or receives an electron
If it loses an electron = positively charged ion
If it receives an electron = negatively charged ion
More than one electron can be received or lost
What size can Carbohydrates be
Small or large carbon molecules
Carbon atoms very readily form bonds with other
Carbon atoms
This forms a “backbone “which are the atoms can be attached – a large number of different types/size molecules to form all based on carbon (Life on Earth thanks to this)
What can carbon containing molecules also be called
Organic molecules
Long chains of monomers = polymers – these are made up of just four elements what are they
Carbon, hydrogen, oxygen, nitrogen
A pair of monosaccharides can combine to form award + examples
Polysaccharides e.g. glucose, galactose , fructose
To all monosaccharides + some disaccharides
Reducing sugars
Reduction = chemical reaction involving?
The gain of electrons or hydrogen
What is a Reducing sugar
A sugar that can donate electrons to another chemical
What test do you use to test for a reducing sugar
Benedicts test
Benedicts reagent = an alkaline solution of copper (II) sulphate
If a reducing sugar is present the Benedicks reagent forms an insoluble red precipitate of copper (I) oxide
In a disaccharide glucose + glucose =
Glucose + fructose =
Glucose + galactose =
Glucose +glucose = maltose
Glucose + fructose = sucrose
Glucose + galactose = lactose
When is the glycosidic bond formed
When are monosaccharide join, a molecule of water is removed ➡️ a condensation reaction occurs ➡️ the bond that is formed is called a glycosidic bond
When water is added to a disaccharide are usually breaks what type of bond. And what is this reaction called
It breaks the glycosidic bond Called hydrolysis (adding water that causes the breakdown)
How do you test for non-reducing sugars, (Some disaccharides don’t change colour with the normal Benedicts test)
First you must hydrolysis it into its monosaccharide component
Polysaccharide polymers formed by many monosaccharide molecules joined together by what bond
Glucose bonds
Perfect for storage because they are the storage of monosaccharides and disaccharides
How do you test for starch
Starch is easily detected because it changes the colour of iodine when in a solution of potassium iodine (goes from yellow to black)
Starch is a polysaccharide found in many parts of what
Of the plant in the form of small grains
Large amounts found in seeds and storage plants e.g. potato tubers (the major energy source in most diets)
Starch is made up of chains of what type of glucose
Alpha glucose
Monosaccharides linked by glycosidic bonds formed by condensation reaction chains can be branched or unbranched
If the chain is wound into a tight coil to make the molecules very compact
What is starches main role
An energy source
Why is starch well suited to be an energy source
1) It is insoluble and therefore doesn’t affect water potential (water is not drawn into the cell by osmosis)
2) because it is large it does not diffuse out of cells
3) it is compact so a lot can be stored in a small space
4) when hydrolysed it forms alpha glucose which is both easily transported and regularly used in respiration
5) because the branches have many ends each and can be acted on by enzymes simultaneously meaning glucose monomers are released very rapidly
Starch is never found an animal cells what is found instead
Glycogen serves the same role
Glycogen (animal starch) is found in animals and bacteria but never in what
Plant cells
Why is glycogen suited for energy storage in animals
1) insoluble so it doesn’t defuse out of cell
2) insoluble so it doesn’t tend to draw water into cell by osmosis
3) compact so a lot can be stored
4) more highly branched so more ends can be acted upon by enzymes for a faster breakdown of glucose monomers (very important because of high metabolic rate)
What is the main difference between Celulose and starch
Celulose is made of monomers of B– glucose
Starch is made of monomers of alpha-glucose
Rather than a coiled chain like starch what does Celulose have
Straight unbranched chains that run parallel to each other allowing for hydrogen bonds to form cross linkages between adjacent chains
Each individual hydrogen bond is weak but the overall number of them makes a strong +a valuable structural material
Cellulose molecules group together to form what
Microfibrils which are arranged in parallel group is called fibres
Cellulase Is a major component of the plant cell wall, why
Provides rigidity And prevents the cell wall from bursting as water enters it by osmosis
Cellulose is very important In the maintenance of stems and leaves to keep them turgid so they can provide a maximum service area for what
Photosynthesis
Lipids are very group of substances that share 4 characteristics
1) they contain carbon, hydrogen and oxygen
2) The proportion of oxygen to carbon and hydrogen is smaller than carbohydrates
3) they are insoluble in water
4) They are soluble in organic solvents e.g. alcohol +
(the main group of lipids = triglycerides(fats + oils) +Phospholipids
What 4 things are lipids useful for
1) Source of energy➡️When oxidise they produce more than twice the energy as the same mass of carbohydrates + release valuable water
2) waterproofing➡️ insoluble in water➡️ insects have waxy lipid cuticles that conserve water, mammals produce an oily secretion from the sebaceous gland in the skin
3) insolation➡️Fats are slow conductors of heat + act as electrical insulators around the myelin sheath around the nerve cells
4) protection➡️ Factor often stored around delicate organs e.g. kidneys
Triglycerides have 3 what combined with what?
Three fatty acids combined with glycerol (glycerine)
What type of bond is there between each fatty acid and glycerol In a triglyceride
What type of reaction is it
Ester Bond
Condensation reaction
Therefore hydrolysis of the triglycerides produces glycerol + 3 fatty acids
Glycerol molecules In all triglyceries are the same, so what is the difference in properties of fats and oils
The variation and fatty acids
They’re over 70 different fatty acids (they all have carboxyl (-COOH) Group with a hydrocarbon chain attached
When is a fatty acid described as saturated
When is a fatty acid described as unsaturated
When the chain has no carbon-carbon double bond
The carbon atoms are linked to the maximum number of hydrogen atoms therefore they are saturated with maximum number of hydrogen atoms
Unsaturated = one double bond = mono unsaturated
= more than one double bond = polyunsaturated
What 4 things make triglycerides useful
1) High ratio of energy store and carbon hydrogen bonds = excellent source of energy
2) lots of energy can be stored in small volume (reduces the mass animals have to carry)
3) large nonpolar molecules = insoluble in water therefore doesn’t affect osmosis
4) releases water when oxidised therefore an important source of water
Phospholipids are similar to lipids except for one molecule what is it
One of the fatty acid molecules is replaced by a phosphate molecule
Fatty acid molecules repel water what is this known as
Phosphate molecules attract water what is this known as
Hydrophobic
Hydrophilic
A phospholipid is made up of two parts what are they
1) hydrophilic head
2) hydrophobic tail
Polar molecules
Molecules that have two ends that behave differently such as phospholipids which have a hydrophobic tail and a hydrophilic head
The phospholipid structure allows for the formation of glycolipids by combining carbohydrates in the cell surface membrane why is this useful
Important in cell recognition in the cell surface membrane
What is the test for lipids called
Emotion test
Amino acid is a basic monomer is that make up polymers called what
Polypeptides - these can combine to form proteins
Every amino acid has a central carbon atom attached to 4 different chemical groups what are they
1) amino group = basic group
2) carboxyl group = acidic group
3) hydrogen atom
4) R (side) group = a variety of different chemical groups (20 naturally occurring amino acids differ only in their R (side) group
Formation of a peptide bond
Amino acid monomers combined to form dipeptides through condensation reaction
What is Polymerisation
Condensation reaction that joins many amino acid monomers - Results in a chain of hundreds of amino acids called polypeptides- The chain forms the structure of any protein
The sequence is determined by DNA
The primary structure of a protein determines what
The shape and function
A single change in one amino acid can change/stop its function
A simple protein can consist of a single chain of what
Polypeptide. What is more commonly made up of a chain of polypeptides
The secondary structure of proteins
The linked amino acids that make up a polypeptide possess both -NH and minus C = O groups on either side of every peptide bond
- The hydrogen = positive charge
- The O = negative charge
- hydrogen plus oxygen = 2 weak hydrogen bonds
- This causes long polypeptide chains to be twisted and 3-D shape (alpha – helix coil)
Tertiary structure of a protein
Maintained by a number of different bonds which are determined by primary structure of the protein
These bonds include:
1)Disulfide Bridges = very strong/not easily broken
2) ionic bonds: formed between carboxyl and amino groups – not involved in forming peptide bonds - Weaker than disulfide bonds + easily broken by changing pH
3) hydrogen bonds: numerous + easily broken
