1A - Biological Molecules

Question 1

What is a polymer

Answer 1

A large molecule composed of many monomers

Question 2

What is a condensation reaction

Answer 2

A reaction in which a chemical bond is formed between two molecules and water is released

Question 3

What is the reaction that breaks polymers and what happens?

Answer 3

Hydrolysis: Water is used to break the bond formed by a condensation reaction forming two monomers

Question 4

Example of two monomers

Answer 4

amino acids

glucose

Question 5

What does a nucleic acid look like?

Answer 5

Pentose sugar bonded to a base and a phosphate

Question 6

What is a carbohydrate?

Answer 6

Substance only containing the elements hydrogen, carbon and oxygen

Question 7

What is a glycosidic bond?

Answer 7

A bond formed between two monosaccharaides

Question 8

What to two monosaccharides form?

Answer 8

A disaccharide

Question 9

Example of a polysaccharide?

Answer 9

Starch

Question 10

Describe a test to find out if a substance contains non-reducing sugars.

Answer 10

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

Question 11

Structure of starch

Answer 11

Polysaccharide
Long chains of alpha glucose(Amylose, amylopectin)
Coiled chain
Compact structure
Hydrogen bonds make it insoluble

Question 12

Structure of cellulose

Answer 12

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

Question 13

Structure of glycogen

Answer 13

Similar to starch but is more branched and has shorter chains.
Alpha glucose
Compact

Question 14

Structure of triglyceride

Answer 14

3 fatty acids attached to glycerol back bone

Ester bond between fatty acids and glycerol

Question 15

Triglycerides are insoluble.

T/F?

Answer 15

True

Question 16

What is a saturated lipid

Answer 16

One that has no double carbon bonds

Question 17

Structure of a phospholipid

Answer 17

Similar to triglyceride but one fatty acid is replaced by a phosphate group

Question 18

What is the primary structure of proteins

Answer 18

The chain/sequence of amino acids

Question 19

What is the secondary structure of proteins

Answer 19

Spiralled primary structure or pleated sheets held by hydrogen bonds

Question 20

Tertiary structure of proteins

Answer 20

3D shape held by ionic bonds and disulphide bridges and hydrogen bonds

Question 21

Quaternary structure

Answer 21

More than one tertiary structure chain

Question 22

Describe a test to test for the presence of proteins

Answer 22

Buirete test

1. Make solution alkaline by adding sodium hydroxide solution
2. Add copper(ii) sulphate solution
3. If proteins are present then the sample will turn purple if not will remain blue

Question 23

What is an enzyme?

Answer 23

A biological catalyst which speed up a reaction without being used up in the reaction.

Question 24

What is activation energy?

Answer 24

The energy required to start a reaction

Question 25

What do enzymes do to the activation energy?

Answer 25

Lower it which speed up the rate of reaction

Question 26

Describe the structure of an enzyme

Answer 26

• Has an active site

- Which is specific to the substrate it will bind to

Question 27

When a substrate fits into an enzyme’s active site it forms a…..

Answer 27

Enzyme-substrate complex

Question 28

Name the two models of enzyme action and explain them.

Answer 28

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.

Question 29

If the tertiary structure of an enzyme is change it is said to have become….

Answer 29

denatured

Question 30

Factors that denature an enzyme

Answer 30

pH
temperature
mutations in genes

Question 31

Measuring the rate of reaction can be done in two ways:

Answer 31

How fast the product is made

How fast the substrate is broken down

Question 32

The effect of temperature in enzyme controlled reactions

Answer 32

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.

Question 33

pH

Answer 33

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.

Question 34

Substrate concentration

Answer 34

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.

Question 35

Enzyme concentration

Answer 35

Increasing this will increase the rate of reaction up until the point where there is more enzymes than substrate.

Question 36

Describe the differences between competitive and non-competitive inhibitors.

Answer 36

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.