1.8 - Factors affecting enzyme action

Question 1

Effect of substrate conc on Ro. enzyme action:

Answer 1

• if fixed and substrate conc is increased, RoR increases in proportion to the conc of the substrate
• at low conc of substrate, the enzyme molecules have a limited no. of susbtrate molecules to collide with - not working at full capacity
• as more substrate is added - active sites gradually become filled
• ROR levels off

Question 2

Effect of enzyme concentration on the RoR:

Answer 2

• enzymes aren’t used up in reactions
• as long as there’s an excess of substrate, an increase in enzyme conc. has a proporitonal increase on the RoR
• if not in excess it has no effect

Question 3

Effect of pH on enzyme action?

Answer 3

• alters the charges on the amino acids that make up the active site
• substrate can’t bind to the AS so an ES-complex cannot form
• can possibly cause the bonds maintaining the tertiary structure to break the active site/change shape (denature)

Question 4

Why is the human body temperature at 37 degrees?

Answer 4

• enzymes may denature at higher temperatures
• additional nutrition to maintain higher body temperatures

Question 5

Effect of Temperature on Enzyme Action:

Answer 5

• A rise in temperature increases the KE of the molecules
• molecules move around quicker and collide with each other more often
• enzyme and susbtrate molecules come together more often in a given time
• more successful collisions resulting in more ES complexes forming so the RoR increases
• can also cause hydrogen bonds to break
• results in the enzyme including AS to change shape
• substrate fits less easily slowing RoR
• at high temps the enzyme bonds are disrupted so it denatures the enzyme preventing a reaction to occur

Question 6

How is the RoR measured?

Answer 6

draw a tangent and find the gradient of the tangent

Question 7

What happens as substrate is used up and how is product amount affected?

Answer 7

• at first there’s a lot of substrate - but no product
  very easy for molecules to come into contact with the empty AS on the enzyme molecules
• All enzyme active sites are filled at any given moment and the substrate is rapidly broken down into its products
  amount of substrate decreases as it’s broken down
  results in the increase of product and reaction keeps progressing
• Becomes more difficult for the substrate molecules to come into contact with the enzyme molecules due to fewer substrate molecules - products may come in the way of substrate molecules and prevent them reaching an AS
  takes longer for substrate molecules to be broken down by the enzyme so RoR decreases

Question 8

Methods of measuring enzyme action

Answer 8

• formation of the product of the reaction
• disappearance of the substrate