Module 6 - 1

Question 1

What is the function of catalysts?

Answer 1

Lower energy required for reaction.

Question 2

What is the difference between enzymes and chemical catalysts in terms of speed?

Answer 2

Enzymes are faster.

Question 3

What are the conditions required for chemical catalysts?

Answer 3

Extreme temperature, pressure, and pH.

Question 4

What is the specificity of enzymes compared to chemical catalysts?

Answer 4

Higher degree of specificity.

Question 5

What is the Circe effect?

Answer 5

Enzyme rates of catalysis can approach the physical limit of rates of diffusion of molecules in solution.

Question 6

What is the equilibrium equation for enzymes?

Answer 6

E + S <—->ES <—–> E + P.

Question 7

What is the substrate?

Answer 7

The molecule acted upon by the enzyme.

Answer 8

The molecule produced by the enzyme.

Question 9

What is the active site?

Answer 9

The portion of enzyme responsible for binding the substrate to formation of an enzyme-substrate complex.

Answer 10

Catalyze the interconversion of substrate and product.

Answer 11

Enzymes don’t rely on harsh conditions.

Question 12

What is the specificity of catabolism?

Answer 12

Isn’t as specific.

Question 13

What is the regulation of enzymes?

Answer 13

Responsive to the dynamic needs of the cell and organism.

Question 14

What is the rate-determining step?

Answer 14

Roughly as fast as the binding of substrates to the enzymes.

Question 15

What is the stereospecificity of enzymes?

Answer 15

Higher degree of specificity.

Question 16

What is the function of the ES complex?

Answer 16

Catalyze the interconversion of substrate and product.

Question 17

What is the 3D cleft?

Answer 17

The active site formed from different parts of the polypeptide chain.

Question 18

What is the function of the active site?

Answer 18

Responsible for binding the substrate to formation of an enzyme-substrate complex.

Question 19

What is the function of enzymes in terms of rate enhancements?

Answer 19

Offer incredible catalytic power.

Question 20

What is an active site?

Answer 20

Small part of enzyme where substrate binds

Answer 21

Unique microenvironments

Question 22

How are substrates bound to enzymes?

Answer 22

Multiple weak interactions

Question 23

What determines specificity of substrate binding?

Answer 23

Precisely defined arrangement of atoms

Answer 24

Substrate binding causing flexibility in enzymes

Question 25

What is the lock and key model?

Answer 25

Model of enzyme-substrate interaction without conformation changes

Question 26

What is the hand in glove model?

Answer 26

Better model of enzyme-substrate interaction with conformation changes

Question 27

When is a reaction spontaneous?

Answer 27

When ΔG is negative

Question 28

What does spontaneous mean?

Answer 28

Reaction proceeds without input of energy and releases energy (exergonic)

Question 29

When can a reaction not take place spontaneously?

Answer 29

When ΔG is positive, input of free energy is required (endergonic)

Question 30

What happens at equilibrium?

Answer 30

No net change in concentrations of products and reactants, ΔG is zero

Question 31

What does ΔG of a reaction depend on?

Answer 31

Free energy of product minus free energy of reactants, independent of transformation steps

Question 32

What information does ΔG provide about reaction rate?

Answer 32

None, only indicates if reaction can take place spontaneously

Question 33

What is activation energy?

Answer 33

ΔG‡ between S and P determining rate at which equilibrium is reached

Question 34

How do enzymes lower activation energy?

Answer 34

Provide alternate, lower-energy pathway between substrate and product

Question 35

What is the relationship between reaction rate and activation energy?

Answer 35

Inverse and exponential

Question 36

What determines equilibrium of a reaction?

Answer 36

Difference in free energy between S and P

Question 37

Do enzymes influence the equilibrium of a reaction?

Answer 37

No, they do not influence the difference in free energy between S and P

Question 38

What is the role of enzymes in a reaction?

Answer 38

Lower activation energy and increase reaction rate.

Question 39

Do enzymes affect the equilibrium of a reaction?

Answer 39

No.

Question 40

What are the two modes of enzyme catalysis?

Answer 40

Chemical and binding effects.

Question 41

What are the forces that lower the activation energy?

Answer 41

Chemical and binding effects.

Question 42

What are the two binding effects of enzymes?

Answer 42

Substrate binding and transition-state stabilization.

Question 43

What is the role of substrate binding in enzyme catalysis?

Answer 43

Provides specificity and catalytic power.

Question 44

How much can catalytic mechanisms limited to binding properties increase reaction rates?

Answer 44

Over 10,000-fold.

Question 45

What is the conceptual overlap between substrate binding and transition-state stabilization?

Answer 45

They both involve the active site of the enzyme.

Question 46

What are the five ways substrate binding promotes reactions?

Answer 46

Reducing entropy, alignment of functional groups, desolvation of substrate, distortion of substrates, and induced fit.

Question 47

What are the four reasons enzymes are better than chemical catalysts?

Answer 47

Their speed, conditions, specificity, and regulation

Question 48

What conditions do enzymes function under

Answer 48

They function under physiological conditions

Question 49

Explain the regulation of enzymes

Answer 49

They are responsive to the dynamic needs of cell and Organism