Enzymes

Question 1

Active site is where..

Answer 1

substrate binds + reaction occurs

Question 2

Explain how enzymes can be denatured due to changes in shape of active site

Answer 2

• pH / temperature affects how protein folds
• changing active site’s shape
• substrate unable to fit into active site so enzyme denatures

Question 3

Devise a method to find the optimum pH of an enzyme that breaks down starch

Answer 3

METHOD
• add enzyme solution
• test for presence of starch
•turns blue black
• repeat with a range of pH solutions

• repeat at different pH values
• with same temp / volume of solutions

TEST FOR STARCH
• add iodine solution
• solution changes from brown to blue-black if starch present

Question 4

What is used to measure amount of energy in food

Answer 4

Calorimetry

Question 5

Calorimetry

Answer 5

• add set volume of water to boiling tube
—> used to measure amount of energy transferred when food burnt
• record start temp of water + burn food using bunsen burner (make sure bb isn’t near water -> inaccurate results)
• record final temp of water when food burnt

Question 6

Energy in food calculation

Answer 6

mass of water X temp change of water x 4.2

energy per gram of food
energy in food / mass of food

Question 7

What happens when a temperature is above optimum

Answer 7

• enzyme denatures
• active site changes shape
• cant bind to substrate