1A - Biological Molecules Flashcards
What is a polymer
A large molecule composed of many monomers
What is a condensation reaction
A reaction in which a chemical bond is formed between two molecules and water is released
What is the reaction that breaks polymers and what happens?
Hydrolysis: Water is used to break the bond formed by a condensation reaction forming two monomers
Example of two monomers
amino acids
glucose
What does a nucleic acid look like?
Pentose sugar bonded to a base and a phosphate
What is a carbohydrate?
Substance only containing the elements hydrogen, carbon and oxygen
What is a glycosidic bond?
A bond formed between two monosaccharaides
What to two monosaccharides form?
A disaccharide
Example of a polysaccharide?
Starch
Describe a test to find out if a substance contains non-reducing sugars.
Benedicts
Add sample to test tube and add Benedicts reagent. Heat solution for a couple of minutes. If colour doesn’t change from blue then non-reducing sugars are present. Then heat a new sample with dilute HCl and add sodium hydrogen carbonate. If the sample stays blue then there are no reducing or non-reducing sugars present
Structure of starch
Polysaccharide Long chains of alpha glucose(Amylose, amylopectin) Coiled chain Compact structure Hydrogen bonds make it insoluble
Structure of cellulose
Long unbranched chains of beta glucose
Each monomer is rotated 180 degrees in relation to each other.
Chains run straight and parallel to each other
Hydrogen bonds between chains creating microfibrils
Structure of glycogen
Similar to starch but is more branched and has shorter chains.
Alpha glucose
Compact
Structure of triglyceride
3 fatty acids attached to glycerol back bone
Ester bond between fatty acids and glycerol
Triglycerides are insoluble.
T/F?
True
What is a saturated lipid
One that has no double carbon bonds
Structure of a phospholipid
Similar to triglyceride but one fatty acid is replaced by a phosphate group
What is the primary structure of proteins
The chain/sequence of amino acids
What is the secondary structure of proteins
Spiralled primary structure or pleated sheets held by hydrogen bonds
Tertiary structure of proteins
3D shape held by ionic bonds and disulphide bridges and hydrogen bonds
Quaternary structure
More than one tertiary structure chain
Describe a test to test for the presence of proteins
Buirete test
- Make solution alkaline by adding sodium hydroxide solution
- Add copper(ii) sulphate solution
- If proteins are present then the sample will turn purple if not will remain blue
What is an enzyme?
A biological catalyst which speed up a reaction without being used up in the reaction.
What is activation energy?
The energy required to start a reaction
What do enzymes do to the activation energy?
Lower it which speed up the rate of reaction
Describe the structure of an enzyme
- Has an active site
- Which is specific to the substrate it will bind to
When a substrate fits into an enzyme’s active site it forms a…..
Enzyme-substrate complex
Name the two models of enzyme action and explain them.
Lock and key - The enzyme and substrate have a complementary shape.
Induced fit - Substrate has to be able to slightly change the active site and then fit onto it.
If the tertiary structure of an enzyme is change it is said to have become….
denatured
Factors that denature an enzyme
pH
temperature
mutations in genes
Measuring the rate of reaction can be done in two ways:
How fast the product is made
How fast the substrate is broken down
The effect of temperature in enzyme controlled reactions
Increasing temp means more kinetic energy and so molecules move faster which increases collisions. However at too high temperatures the vibrations in the enzyme break bonds holding the shape of the enzyme which changes the active site and so it becomes denatured.
pH
Above and below the optimum pH value ionic and hydrogen bonds are disrupted by H+ and OH- ions which changes the active site and denatures the enzyme.
Substrate concentration
Increasing this will increase rate of reaction up until a point where the substrate concentration > enzyme concentration. This is because at this point there are no more active site to catalyse the reaction and so add more make no difference.
Enzyme concentration
Increasing this will increase the rate of reaction up until the point where there is more enzymes than substrate.
Describe the differences between competitive and non-competitive inhibitors.
Competitive - Have a similar shape to the substrate and so bind to the active site of the enzyme instead of the substrate.
Non-competitive - Bind to other parts of the enzyme other than the active site and cause a change in the shape of the active site.
