Biochem Recitation Quiz 3

Front 1

1. ∆G0 is a representation of:

Back 1

B & C

B. The energy produced by a reaction under standard conditions

C. The sum of the energy in the products minus the substrates

Front 2

2. If the above had a ∆G0 of 0 Kcal, and the reactants were at the following concentration, A=10, B=lO, C=1 and D=1O; what would the ∆G be?

Back 2

-1 .36 Kcal

Front 3

3. For another reaction as described above, at equilibrium A=[100mM], B=[10 nM], C=[10 mM] and D=[1 nM]; what is the equilibrium constant for this reaction:

Back 3

0.01

Front 4

4. What is the ∆G0 for the above reaction (question 3)?

Back 4

2.72

Front 5

5. The transition state for enzvmes involves:

Back 5

A & B

A. Association of products and reactants with the enzyme.

B. The use of chemical around of the enzyme.

Front 6

6. An enzvme catalvtic site:

Back 6

None of the above.

Front 7

7. The above represents what?

Back 7

A & C

A. A reaction involving a transition complex.

C. An illustration of a chemical reaction involving an enzyme.

Front 8

8. Which equation gives the rate of formation of product?

Back 8

Kcat[ES]

Front 9

9. The equation diagram from problem 8 is primarily of value in describing the formation of product at which stage of the reactions?

Back 9

Very early followinq addition of enzyme to substrate.

Front 10

10. For the above enzyme reaction, the compounds are burned to produce the following energy: AB = 10 Kcal, CD = 2 Kcal, AD = 10 Kcal and BD = 1 Kcal. What is the ∆G0 for the entire reaction?

Back 10

-1 Kcal

Front 11

11. Which is true?

Back 11

None of the above.

Front 12

12. The Gibbs free energy is which of the following?

Back 12

b) The difference between the energy of the substrates and products.

Front 13

13. According to the above reaction equation, which equation below gives the rate of formation of the transition complex?

Back 13

K1[S] + K4[P]

Front 14

14. According to the above reaction equation in question 13, which equation below gives the rate of formation of the transition complex at time = 0?

Back 14

K1[S]

Front 15

15. Why isn't temperature a factor in the equation for ∆G0?

Back 15

Temperature does not alter the energetics of a reaction.

Front 16

16. The above reaction comes to equilibrium at A = 10 units, B = 1 unit, C = 1 unit and D = 10 units. What is the ∆G0 for t his reaction?

Back 16

0

Front 17

17. The rate at which a reaction reaches equilibrium is dependent upon:

Back 17

The enerqy of the transition state

Front 18

18. From the above data, what is the Km (mMol/I) ?

Back 18

2

Front 19

19. What is one characteristic of a sequential reaction mechanism?

Back 19

c. All substrates must bind before any products can be produced.

Front 20

20. What type of inhibition does the above diagram refer to?

Back 20

Non-competitive

Front 21

21. Is there a way for the substrate to overcome this type of inhibition?

Back 21

No.

Front 22

22. What position on the enzyme does the inhibitor bind to?

Back 22

To a site on the enzyme other than the catalytic site. Note, we at times call this an allosteric site. However, the word allosteric is often used more in reference to the special situation where the substrate itself binds not only to the catalytic site, but also to another, regulatory site on the enzyme.

Front 23

23. What changes in this type of inhibition, Km or Vmax.

Back 23

Vmax

Front 24

24. (A) What type of inhibition does the above diagram refer to?

Back 24

Allosteric substrate stimulation.

Front 25

24. (B) Is there a way for the substrate to overcome this type of inhibition?

Back 25

The substrate does not overcome this regulation but is rather responsible for it.

Front 26

24. (C) What position on the enzyme does the inhibitor bind to?

Back 26

In this case, the substrate binds to two sites, the catalytic site and a second, allosteric site. This binding can cause either stimulation or inhibition.

Front 27

24. (D) What changes in this type of inhibition, Km or Vmax.

Back 27

In this case, the resulting profile does not follow Mechaelis Menton kinetics, so discussion of Km and Vmax is not relevant.

Front 28

25. Collagen consists of:

Back 28

A & B

A. Three extended chains of amino acids.

B. A short repeating amino acid motif that generally includes proline.

Front 29

26. What can be said of the globin protein?

Back 29

A & B

A. It has many hydrophilic amino acids externally.

B. It consists of primarily hydrophobic amino acids internally.

Front 30

27. Enzymes increase the rate of reaction by doing which of the following?

Back 30

Reducing the activation energy of the transition state.

Front 31

28. The Delta G0 is which of the following?

Back 31

The difference between the energy of substrates and products.

Front 32

29. The overall rate of a reaction is determined by:

Back 32

The difference between the energy of the products minus the reactants.

Front 33

30. The above reaction comes to equilibrium at A=1, B=1, C=1 and D=10. What is the ∆G0 for this reaction?

Back 33

- 1.3 Kcal

Front 34

31. If the ∆G0 for this reaction were 2.7 and A=1, B=1 and C=1; what would the concentration of D be at equilibrium?

Back 34

.01

Front 35

32. If each of these peptides were part of an alpha helix, which would you expect to be most likely to be located on the surface of the protein?

Back 35

Val, Ile, Ser, Asp

Front 36

47. The overall rate of a reaction is determined by:

Back 36

None of the above.

Front 37

48. The above graph represents the initial velocity as a function of the substrate concentration. What is the Vmax?

Back 37

7

Front 38

49. Which of the following is true under the following conditions: The enzyme concentration is 5 nM, the substrate concentration is 5mM and the Km is 5uM.

Back 38

The enzyme is saturated with substrate.

Front 39

50. Give an explanation for the reduction of Vmax in non-competitive inhibition.

Back 39

The inhibitor effectively removes some of the enzyme, thereby making it appear that less total enzyme is present and thus a lower Vmax is seen for the enzyme.

Front 40

51. In a sequential reaction:

Back 40

The enzyme always exhibits substrate inhibition.

Front 41

52. (A) What type of inhibition is exhibited in each of the graphs below?

Back 41

Substrate stimulation

Front 42

52. (B) What type of inhibition is exhibited in each of the graphs below?

Back 42

non-competitive

Front 43

52. (C) What type of inhibition is exhibited in each of the graphs below?

Back 43

No inhibition, normal mechaelis kinetics.

Front 44

53. In each case, can the inhibition be overcome by increasing substrate?

Back 44

No.

Front 45

54. (A) Where is the site of inhibition?

Back 45

Substrate.

Front 46

54. (B) Where is the site of inhibition?

Back 46

Allosteric site.

Front 47

54. (C) Where is the site of inhibition?

Back 47

No inhibition.

Front 48

55. (A) Is the Km altered?

Back 48

Yes.

Front 49

55. (B) Is the Km altered?

Back 49

No.

Front 50

55. (C) Is the Km altered?

Back 50

Not applicable.

Front 51

33. If each of these peptides were part of a beta sheet, which would you expect to be most likely to be located on the surface of the protein?

Back 51

Phe, Ser, Ile, Arg

Front 52

34. Enthalpy in the Gibbs free energy equation is the:

Back 52

The energy of the products minus the energy of the reactants

Front 53

35. Enthalpy in the Gibbs free energy equation is the:

Back 53

Vmax

Front 54

36. According to the above reaction equation, which equation below describes the condition at equilibrium?

Back 54

[S]K1 + [P]K4 = [X]K2 + [X]K3

Front 55

37. The Gibbs free energy is which of the following?

Back 55

The difference between the energy of the substrates and products.

Front 56

38. The above graph represents the initial velocity as a function of the substrate concentration. Why does it begin rapidly at first and then gradually decline to near a horizontal line.

Back 56

Because the enzyme involved becomes saturated at high substrate concentration.

Front 57

39. What are the characteristics of a ping-pong, double displacement reaction?

Back 57

Front 58

40. What type of inhibition is exhibited in the graph above?

Back 58

Uncompetitive

Front 59

41. What is altered by the inhibitor above (referring to question 40)?

Back 59

B & C

B. Km

C. Vmax

Front 60

42. When concentration of substrate is equal to Km then.

Back 60

[E] = [ES]

Front 61

43. When concentration of substrate is greater than Km which is true?

Back 61

A & C

A. Almost all active sites are filled.

C. Reaction rate is independent of substrate concentration.

Front 62

44. When concentration of substrate is less than Km which of the following is true?

Back 62

B & C

B. Rate is proportional to [S].

C. [E] is about equal to [Etotal]

Front 63

45. For another reaction as described above, at equilibrium A=[100mM], B=[10 nm], C=[10 mM] and D=[10nM]; what is the equilibrium constant for this reaction:

Back 63

0.1

Front 64

46. In the Gibbs free energy equation, entropy is related to:

Back 64

Concentration of the products divided by that of the reactants.