Enzymes

Question 1

Enzymes

Answer 1

Proteins which speed up the rate of metabolic reactions - they are biological catalysts

Question 2

Active site

Answer 2

An area of the enzyme that is made up of only a few amino acids

Question 3

Substrate

Answer 3

The molecule that binds to the active site on the enzyme

Question 4

Activation energy

Answer 4

The amount of energy supplied to the chemicals before the start of the reaction - enzymes lower the activation energy

Question 5

Enzyme-substrate complex

Answer 5

When the substrate binds the the active site on the enzyme

Question 6

Induced fit model

Answer 6

1) Substrate doesn’t fit perfectly into the active site yet
2) The active site changes shape so it is complementary to allow the substrate to bind
3) Enzyme-product complex forms - gives 2 products (substrate splits in half)
4) Enzyme molecule resumes its original shape and the active site is free to accept another pair of substrate molecules

Question 7

Factors affecting enzyme action - Temperature

Answer 7

• Rate of reaction increases up to the optimum temperature as the kinetic energy of the enzyme increases
• Above the optimum temp, rate of reaction decreases as the enzyme becomes denatured

Question 8

Factors affecting enzyme action - pH

Answer 8

• pH affects the enzymes shape as it can disrupt the bonds in the tertiary structure of the enzyme

Question 9

Factors affecting enzyme action - Enzyme concentration

Answer 9

• Rate of reaction increases as enzyme concentration increases as there are more active sites for substrates to bind to
• However, increasing the enzyme concentration beyond a certain point has no effect on the rate of reactions as there are more active sites than substrates

Question 10

Factors affecting enzyme action - Substrate concentration

Answer 10

• Rate of reaction increases as the substrate concentration increases as more enzyme-substrate complexes are formed

Question 11

Enzyme inhibition - Competitive inhibitors

Answer 11

Have a similar structure to substrates and will compete with the substrate for the active site
- Increasing substrate concentration can reduce inhibition

Question 12

Enzyme inhibition - Non-competitive inhibitors

Answer 12

Bind to the enzyme at an alternative site, which alters the shape of the active site which prevents substrate from binding to them
- Increasing substrate concentration has no effect