Enzymes

Question 1

What is the catalyst features of enzymes?

Answer 1

• Biological Catalysts -> Lowers the activation energy of reactions -> more substrates can undergo reaction per unit time
• Large catalytic power

Question 2

What is the specificity features of enzymes

Answer 2

Enzyme specificity -> selective in the substrates it interacts and reacts with

Question 3

What is the structural feature of enzymes?

Answer 3

They have structure similar to that of PROTEIN
- Can undergo denaturation depending on temperature and pH of environment

Question 4

What is the lock and key hypothesis?

Answer 4

Active site is structurally complementary to the substrate of the enzyme

Question 5

What is the induced fit hypothesis?

Answer 5

• Substrate binds to active site of enzyme -> Active site undergoes conformational changes
• Achieves a better fit with the substrate

Question 6

How do substrates bind to enzyme?

Answer 6

• Substrate binds to structurally complementary active site through hydrogen bonds, ionic bonds and Van der Waals interactions -> forms enzyme- substrate complex
• Chemical changes in enzymes-substrate complex -> forms enzyme-product complex
• Product then released from enzyme

Question 7

How is enzymatic activity affected up to optimum temperature?

Answer 7

• Increasing temperature -> increasing kinetic energy
• More frequent effective collisions -> more enzyme substrate complexes formed per unit time
• More products formed

Question 8

How is enzymatic activity affected above optimum temperature?

Answer 8

• Temperature increases -> kinetic energy increase -> vibrations
• Bonds in enzyme structure disrupted -> enzymes begin to denature
• Active site no longer structurally complementary to substrate
• Substrate cannot bind to enzyme -> sharp decrease in products formed

Question 9

How does pH affect enzymatic activity?

Answer 9

• Enzymes only active over a certain pH range
• H+ ion concentration causes hydrogen bonds and ionic bonds to be distrupted
• Enzyme structure denatures
• Active site no longer structurally complementary to substrate
• Substrate cannot bind to enzyme -> decrease in products formed

Question 10

How does concentration of substrate/enzyme affect enzymatic activity

Answer 10

• Substrate/Enzyme concentration increases -> rate of effective collisions increases
• More enzyme-substrate complexes formed per unit time
• Rate of reactions increase

Question 11

Saturation effect of substrate/enzyme concentration

Answer 11

• Peak where increased enzyme/substrate concentration stops affecting rate of reaction
• Every active site is already occupied by substrate

Question 12

How does enzyme inhibition affect enzymatic activity?

Answer 12

• Competitive inhibitors -> structural semblance to substrate -> can bind to active site
• Enzyme-inhibitor complex formed
• Less enzyme-substrate complexes can be formed

Question 13

How can the effects of enzyme inhibition be offset?

Answer 13

• increasing concentration of substrates can offset this
• substrates outcompete inhibitors -> rate of reaction maximised