Enzymes

Question 1

What’s the role of an enzyme?

Answer 1

Lower activation energy of reaction and speeds up the rate of reaction

Question 2

Describe the lock and key model

Answer 2

-Active site is a fixed shape/doesn’t change shape
-After a successful collision an enzyme substrate complex forms leading to reaction?

Question 3

What is one limitation of the lock and key model?

Answer 3

It’s old and outdated

Question 4

Describe the induced fit model

Answer 4

1. Before the reaction, enzyme active site, not completely complimentary to substrate
2. active site changes shape as substrate binds, add an enzyme substrate complex forms
3. this puts a strain on bonds in substrate, leading to a reaction

Question 5

What’s an pro of the induced fit model?

Answer 5

It’s recent and accepted

Question 6

Describe the specificity of enzymes

Answer 6

-enzymes have a specific shape tertiary structure and active site
-active site is complementary to a specific substrate
-forms and enzyme substrate complex

Question 7

Describe the effect of enzyme concentration on the rate of enzyme controlled reactions?

Answer 7

• Increasing enzyme conc → rate of reaction increases
• More enzymes → more available active sites → more successful E-S collisions and E-S complexes

Question 8

Describe the effect of substrate concentration on the rate of enzyme controlled reactions

Answer 8

• Increasing substrate concentration → rate or reaction increases
• More successful E-S collisions and E-S complexes
• At a certain point ROR plateaus → all active sites are saturated

Question 9

Describe the effect of temperature on the rate of enzyme controlled reactions

Answer 9

• Increasing temp unto to optimum → rate of reaction increases
• Increase in kinetic energy → more successful E-S collisions and complexes
• Enzymes denature → tertiary structure and active site changes shape (hydrogen/ionic bonds break)
  
  • Fewer E-S collisions and E-S complexes (substrate won’t bind to active site)

Question 10

Describe the effect of pH on the rate of enzyme controlled reactions

Answer 10

• pH above/below optimum pH → rate of reaction decreases
• Enzymes denature → tertiary structure and active site changes shape (hydrogen/ionic bonds break)
• Fewer E-S collisions ES complexes

Question 11

What affect do competitive inhibitors have on the rate of reaction?

Answer 11

Competitive inhibitors decrease the rate of reaction

Question 12

How do competitive inhibitors work?

Answer 12

• decrease ROR
• similar shape of substrate
• blocks active site so substrates can’t bind
• fewer E-S complexes
• Increasing substrate conc → reduces the effect of inhibitors

Question 13

How do non-competitive inhibitors work?

Answer 13

• decrease the rate of reaction
• Binds away from the active site (allosteric site)
• Active site changes shape, so substrate combine to active site
• Fewer E-S complexes
• increasing the substrate complex concentration has no effect on the rate of reaction → permanent change to active site

Question 14

Where do you noncompetitive inhibitor binds on the enzyme?

Answer 14

The allosteric site

Question 15

What affect does non-competitive inhibitors have on the rate of reaction?

Answer 15

Decreases the rate of reaction