1.3 - Proteins

Question 1

Draw the general structure of an amino acid

Question 2

What is the bond formed between two amino acids in a condensation reaction?

Answer 2

Peptide bond

Question 3

How is a dipeptide formed?

Answer 3

Condensation of two amino acids

Question 4

How is a polypeptide formed?

Answer 4

Condensation of many amino acids

Question 5

3 types of bond that contribute to the tertiary structure of a protein (shape)

Answer 5

Hydrogen bonds, ionic bonds, disulfide bridges

Question 6

Describe the primary structure of a protein

Answer 6

The amino acid sequence

Question 7

Describe the secondary structure of a protein

Answer 7

2D folding of polypeptide chain as a result of hydrogen bonding

Question 8

Describe the tertiary structure of a protein

Answer 8

3D folding of a polypeptide chain due to interactions between R groups

Question 9

Describe the quaternary structure of a protein

Answer 9

Multiple polypeptide chains

Question 10

Describe the Biuret test for proteins

Answer 10

Add Biuret
Lilac

Question 11

What is an enzyme?

Answer 11

Biological catalysts that increase the rate of reaction by lowering the activation energy and providing an alternate reaction pathway

Question 12

Describe the induced fit model of enzyme action

Answer 12

Substrate binds to active site - ESC forms
Active site changes shape to it is complementary to substrate
Bonds are broken and formed in substrate

Question 13

Why are enzymes referred to as specific?

Answer 13

They have a specific tertiary structure (active site) which is complementary to a specific substrate

Question 14

Describe the effect of enzyme concentration on the rate of reaction

Answer 14

Increasing enzyme concentration increases the rate of reaction

Question 15

Describe the effect of substrate concentration on the rate of reaction

Answer 15

As substrate concentration increases rate of reaction increases, until it plateaus due to other limiting factor e.g enzyme concentration

Question 16

Describe the effect of concentration of competitive inhibitors on the rate of reaction

Answer 16

Higher concentration of competitive inhibitor means a slower rate of reaction
Rate can be increased by increasing substrate concentration

Question 17

Describe the effect of concentration of non-competitive inhibitor on the rate of reaction

Answer 17

Higher concentration of non-competitive inhibitor means slower rate of reaction
Rate cannot be increased by increasing substrate concentration

Question 18

Describe how a competitive inhibitor works

Answer 18

Inhibitor similar shape to substrate
Binds to active site
Prevents ESC forming

Question 19

Describe how a non-competitive inhibitor works

Answer 19

Attaches to enzyme at allosteric site
Changes tertiary structure (active site)
So active site and substrate no longer complementary so no substrate can bind

Question 20

Describe lock and key enzyme model

Answer 20

The enzyme and substrate fit together perfectly and form an ESC