JOURNALS!!!!!!!!!! Chapter 8 Enzymes

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10-9 journal and 10-16-08

Please use your textbook and compare and contrast the structure of ATP with the structure of DNA. Also please explain what each one is used for.

10-17 and 10-22 Journal

1) Which of the following has more free energy…option “a” or option “b”? Please explain your answer…how did you know this?
a. Glutamic acid + ammonia + ATP
b. Glutamine + ADP + P
2) How is ATP used/recycled to transfer energy from an exergonic process to an endergonic process?
3) Many spontaneous reactions occur very slowly…why don’t they all happen instantly if they are “spontaneous?”
4) Explain this:

10-21 and 10-27
1) How can an activator and an inhibitor have different effects on an allosterically regulated enzyme?
2) Explain the difference between competitive and noncompetitive inhibition. Which one is worse for a cell and why?

10-23 journal and 10-31
1) Consider this reaction, A+B -à C + D + energy
a. Is this reaction exergonic/endergonic?
b. What are the reactants/products

2) Which of the following describes an allosteric site?
a. The same as the active site
b. Nonprotein in nature
c. Where ATP attaches and gives up its energy
d. Often involved in feedback inhibition
e. All of the above
3) If you want to increase the amount of product per unit of time of an enzyme reaction, do NOT increase…
a. Amount of substrate
b. Amount of enzyme
c. The temperature (somewhat)
d. The pH
e. All of the above

4a) Which curve represents the behavior of an enzyme taken from a bacterium that lives in hot springs at temperatures of 70°C or higher?
A) curve 1
B) curve 2
C) curve 3
D) curve 4
E) curve 5

4b) Which curve was most likely generated from analysis of an enzyme from a human stomach where conditions are strongly acid?
A) curve 1
B) curve 2
C) curve 3
D) curve 4
E) curve 5

5) Which of the following is true for all exergonic reactions?
A) The products have more total energy than the reactants.
B) The reaction proceeds with a net release of free energy.
C) Some reactants will be converted to products with more free energy.
D) A net input of energy from the surroundings is required for the reactions to proceed .
E) The reactions are nonspontaneous.

****NOTE ATP HYDROLYSIS RELEASES ABOUT 7Kcal of ENERGY!!!!!!****

Talk about ATP as a allosteric inhibitor to a pathway!!!!

Journal 10-28 and 10-31
1) What term is used to describe the transfer of free energy from catabolic pathways to anabolic pathways?
A) feedback regulation
B) bioenergetics
C) energy coupling
D) entropy
E) cooperativity

2) Which of the following is not true of enzymes?
A) Enzyme catalysis is dependent on the pH and temperature of the environment.
B) Enzyme catalysis is dependent on the three-dimensional structure or conformation of the enzyme.
C) Enzymes provide activation energy for the reaction they catalyze rather than using ATP.
D) Enzymes are composed primarily of protein, but they may bind nonprotein cofactors.
E) Enzyme activity can be inhibited if the enzyme's allosteric site is bound with a noncompetitive inhibitor.

3) During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a ΔG of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the ΔG for the new reaction?
A) -40 kcal/mol
B) -20 kcal/mol
C) 0 kcal/mol
D) +20 kcal/mol
E) +40 kcal/mol

4) According to the induced fit hypothesis of enzyme catalysis, which of the following is correct?
A) The binding of the substrate depends on the shape of the active site.
B) Some enzymes change their structure when allosteric activators bind to the enzyme.
C) A competitive inhibitor can outcompete the substrate for the active site.
D) The binding of the substrate changes the shape of the enzyme's active site.
E) The active site creates a microenvironment ideal for the reaction.

5) Consider the following: Succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the ratio of succinate to malonic acid reduces the inhibitory effect of malonic acid. Which of the following is correct?
A) Succinate dehydrogenase is the enzyme, and fumarate is the substrate.
B) Succinate dehydrogenase is the enzyme, and malonic acid is the substrate.
C) Succinate is the substrate, and fumarate is the product.
D) Fumarate is the product, and malonic acid is a noncompetitive inhibitor.
E) Malonic acid is the product, and fumarate is a competitive inhibitor.

6) Consider the following: Succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the amount of succinate and decreasing the amount of malonic acid reduces the competitive inhibitory effect of malonic acid. Which of the following is correct?

A) Succinate dehydrogenase is the enzyme, and fumarate is the substrate.
B) Succinate dehydrogenase is the enzyme, and malonic acid is the substrate.
C) Succinate is the substrate, and fumarate is the product.
D) Fumarate is the product, and malonic acid is a noncompetitive inhibitor.
E) Malonic acid is the product, and fumarate is a competitive inhibitor.

7) Which of the following statements correctly indicate(s) the role of ATP or ADP as an allosteric regulator?
A) ATP is an allosteric inhibitor of catabolic pathways.
B) ADP is an allosteric activator of catabolic pathways.
C) ATP is an allosteric activator of anabolic pathways.
D) A and B only
E) A, B, and C

8) An increase in the level of cellular ATP is likely to occur under which of the following conditions? NOTE this is not the process of making ATP!!!
A) increased activity of catabolic pathways
B) decreased activity of anabolic pathways
C) allosteric inhibition of anabolic pathways
D) A and B only

NOTE: HEAT IS NOT USABLE BIOLOGICAL ENERGY!!!!!!! IT IS THE BIPRODUCT OF ENERGY BEING RELEASED!!!!
A+B à C+D+ energy…………………what side of the equation has more free/usable energy????