EQ's

Question 1

State the word/phrase which best describes a region or surface of an enzyme where a substrate can bind

[1 mark]

Answer 1

Active site

Question 2

State the word/phrase that best describes the energy required for a chemical reaction to take place

[1 mark]

Answer 2

Activation energy

Question 3

Explain what is meant by enzyme specificty

[3 marks]

Answer 3

1. The specific shape of the enzyme’s active site is
2. complementary to the shape of the specific substrate
3. And any other shaped substrate will not fit

Question 4

Suggest how a substrate changing shape could assist enzyme action according to the ‘induced fit’ hypothesis

[1 mark]

Answer 4

it will allow the enzyme to break the bonds in the substrate more easily

Question 5

Explain how DNA determines the specific shape of enzymes

[4 marks]

Answer 5

1. The order of the bases in the DNA determines the order of amino acids.
2. The primary structure causes the proteins to fold into the secondary structure with alpha helixes and beta pleated sheets
3. These fold into a precise 3-dimensional shape in the tertiary structue due to hydrogen bonds, ionic bonds and hydrophobic/hydrophyllic interactions

Question 6

Methanol is a poision not because of wht it does to the body itself but becase the enzyme dehydrogenase oxidises it to formaldehyde, which is a potent poison.
A treatment of methanol poison is to give a patient ethanol.

Why is this effective?

[4 marks]

Answer 6

1. Ethanol is a competetive inhibitor which is similar in shape to the substrate molecule methanol.
2. Ethanol is complementary in shape to the active site of the dehydrogensae enzyme and competes with the methanol substrate molecule
3. When the ethanol binds
   with the dehydrogenase an enzyme-inhibitor complex is formed, this stops the methanol susbtrate molecule from binding with the enzyme and so prevents the enzyme from catalysing the reaction and breaking down methanol into formaldehyde.

1. mention the inhibitor and substrate involved
2. define a competetive inhibitor hile using the context to answer the question