Question 1

The development of bacterial resistance to antibiotics is an example of what engine of evolution?

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Question 2

You are studying metabolic pathways and discover that two pathways intersect so that the enzyme basinase participates in both of the intersecting pathways,in one case using substrate K and in the other using substrate M.When presented with substrate K in amounts significantly larger than M,basinase converts K to L which leads eventually to the production of the end product R.The activity of the second pathway is depressed simultaneously.In the presence of large amounts of substrate M and lower amounts of substrate K,the second pathway is activated and culminates in the production of that pathway's end product Y.The activity of the first pathway is depressed simultaneously.What are the alternative substrates K and M acting like?

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Question 3

You isolate the enzyme that synthesizes folic acid in bacteria and conduct some enzyme kinetics experiments.You find,not surprisingly,that sulfa drugs inhibit the enzyme's activity.What happens to the Vmax and KM of this enzyme when it is treated with sulfa drugs? Why do sulfa drugs have no effect on human metabolism?

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Question 4

Do the equations below represent coupled reactions? If not,why not? A + B <-> C + D ($\Delta$G = +5.4 kcal/mole) D + F <-> G + H ($\Delta$G = -4.4 kcal/mole)

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Question 5

Below is a segment of a cell's collection of biochemical pathways.M is a product of one series of these reactions.It is also a regulatory molecule.Look at the pathway below and indicate the position(s)at which M is most likely to act as a feedback inhibitor when its concentration gets too high.

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Question 6

If ATP is present in relatively high amounts,what is likely to happen to the rate of glycolytic activity in that cell?

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Question 7

A number of antibiotics attack prokaryotic protein synthesis,but not eukaryotic protein synthesis.Name two common antibiotics that work this way.What is their site of action and why don't they affect eukaryotic protein synthesis?

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Question 8

If a reaction vessel is cold to the touch and the reaction results in an increase in order in the reaction vessel,is the reaction spontaneous or nonspontaneous? Explain your answer.

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Question 9

Penicillin is an irreversible inhibitor of the transpeptidases,enzymes that cross-link components of the bacterial cell wall.The cell wall is thus fragile and the bacteria die.Penicillin and its derivatives are structural analogs of the natural substrates of these enzymes.Why doesn't penicillin normally kill humans,unless a severe allergic reaction (anaphylaxis)develops? How does penicillin inhibit transpeptidase?

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Question 10

An enzyme has a K_M of 20 µM and a V_max of 50 mmoles of product/minute/µg of enzyme.After exposure to an inhibitor and analysis on a Lineweaver - Burk plot the following values are obtained: -1/ K_M = - 0.05 liters/µmole and 1/ V_max = 0.04 (mmoles of product/minute/µg of enzyme)-1.What kind of inhibitor was used in the experiment?

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Question 11

Why are alcoholic beverages often made in airtight containers?

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Question 12

Why has the pharmaceutical industry drastically cut resources devoted to the development of new antibiotics?

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Question 13

Do the equations below represent coupled reactions? If not,why not? A + B <-> C + D ($\Delta$G = -5.4 kcal/mole) E + F <-> G + H ($\Delta$G = +4.4 kcal/mole)

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Question 14

What is the reason for treating a patient simultaneously with two antibiotics against the same bacterium?

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Question 15

Where is S.aureus usually found in humans? What kind of hospitalized patients develop life-threatening S.aureus infections? Distressingly,instead of just showing up in hospitals,methicillin-resistant S.aureus (MRSA)is showing up in other places.What are some examples?

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Question 16

What is unusual about the mechanism by which vancomycin inhibits transpeptidation of the bacterial cell wall? Why is it more difficult for bacteria to develop resistance to vancomycin than to other antibiotics?

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Question 17

If an antibiotic were found to bind to a site on an essential bacterial enzyme other than the active site,what would its most likely mode of action be?

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Question 18

In the reaction A + B <-> C + D,how might the reaction take place in the cell if the $\Delta$G is very positive? How might the reaction occur if the $\Delta$G is slightly positive?

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Question 19

4 ATPs per glucose molecule are made during glycolysis.Why then is there a net production of only 2 ATPs for each glucose molecule in the pathway?

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Question 20

You are observing an enzyme driven reaction.To the reaction mixture you add a chemical X which inhibits the reaction.If you add more substrate,the reaction rate approaches the V_max of the uninhibited reaction.Furthermore,the structure of X is similar to the natural substrate.What kind of inhibitor is X?

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Quiz 3: Bioenergetics,enzymes and Metabolism

The development of bacterial resistance to antibiotics is an example of what engine of evolution?

Do the equations below represent coupled reactions? If not,why not? A + B <-> C + D ( $\Delta$ G = +5.4 kcal/mole) D + F <-> G + H ( $\Delta$ G = -4.4 kcal/mole)

Below is a segment of a cell's collection of biochemical pathways.M is a product of one series of these reactions.It is also a regulatory molecule.Look at the pathway below and indicate the position(s)at which M is most likely to act as a feedback inhibitor when its concentration gets too high.

If ATP is present in relatively high amounts,what is likely to happen to the rate of glycolytic activity in that cell?

A number of antibiotics attack prokaryotic protein synthesis,but not eukaryotic protein synthesis.Name two common antibiotics that work this way.What is their site of action and why don't they affect eukaryotic protein synthesis?

If a reaction vessel is cold to the touch and the reaction results in an increase in order in the reaction vessel,is the reaction spontaneous or nonspontaneous? Explain your answer.

Why are alcoholic beverages often made in airtight containers?

Why has the pharmaceutical industry drastically cut resources devoted to the development of new antibiotics?

Do the equations below represent coupled reactions? If not,why not? A + B <-> C + D ( $\Delta$ G = -5.4 kcal/mole) E + F <-> G + H ( $\Delta$ G = +4.4 kcal/mole)

What is the reason for treating a patient simultaneously with two antibiotics against the same bacterium?

Where is S.aureus usually found in humans? What kind of hospitalized patients develop life-threatening S.aureus infections? Distressingly,instead of just showing up in hospitals,methicillin-resistant S.aureus (MRSA)is showing up in other places.What are some examples?

What is unusual about the mechanism by which vancomycin inhibits transpeptidation of the bacterial cell wall? Why is it more difficult for bacteria to develop resistance to vancomycin than to other antibiotics?

If an antibiotic were found to bind to a site on an essential bacterial enzyme other than the active site,what would its most likely mode of action be?

In the reaction A + B <-> C + D,how might the reaction take place in the cell if the $\Delta$ G is very positive? How might the reaction occur if the $\Delta$ G is slightly positive?

4 ATPs per glucose molecule are made during glycolysis.Why then is there a net production of only 2 ATPs for each glucose molecule in the pathway?

Quiz 3: Bioenergetics,enzymes and Metabolism

The development of bacterial resistance to antibiotics is an example of what engine of evolution?

Do the equations below represent coupled reactions? If not,why not? A + B <-> C + D ( Δ\DeltaΔ G = +5.4 kcal/mole) D + F <-> G + H ( Δ\DeltaΔ G = -4.4 kcal/mole)

Below is a segment of a cell's collection of biochemical pathways.M is a product of one series of these reactions.It is also a regulatory molecule.Look at the pathway below and indicate the position(s)at which M is most likely to act as a feedback inhibitor when its concentration gets too high.

If ATP is present in relatively high amounts,what is likely to happen to the rate of glycolytic activity in that cell?

A number of antibiotics attack prokaryotic protein synthesis,but not eukaryotic protein synthesis.Name two common antibiotics that work this way.What is their site of action and why don't they affect eukaryotic protein synthesis?

If a reaction vessel is cold to the touch and the reaction results in an increase in order in the reaction vessel,is the reaction spontaneous or nonspontaneous? Explain your answer.

Why are alcoholic beverages often made in airtight containers?

Why has the pharmaceutical industry drastically cut resources devoted to the development of new antibiotics?

Do the equations below represent coupled reactions? If not,why not? A + B <-> C + D ( Δ\DeltaΔ G = -5.4 kcal/mole) E + F <-> G + H ( Δ\DeltaΔ G = +4.4 kcal/mole)

What is the reason for treating a patient simultaneously with two antibiotics against the same bacterium?

Where is S.aureus usually found in humans? What kind of hospitalized patients develop life-threatening S.aureus infections? Distressingly,instead of just showing up in hospitals,methicillin-resistant S.aureus (MRSA)is showing up in other places.What are some examples?

What is unusual about the mechanism by which vancomycin inhibits transpeptidation of the bacterial cell wall? Why is it more difficult for bacteria to develop resistance to vancomycin than to other antibiotics?

If an antibiotic were found to bind to a site on an essential bacterial enzyme other than the active site,what would its most likely mode of action be?

In the reaction A + B <-> C + D,how might the reaction take place in the cell if the Δ\DeltaΔ G is very positive? How might the reaction occur if the Δ\DeltaΔ G is slightly positive?

4 ATPs per glucose molecule are made during glycolysis.Why then is there a net production of only 2 ATPs for each glucose molecule in the pathway?

Do the equations below represent coupled reactions? If not,why not? A + B <-> C + D ( $\Delta$ G = +5.4 kcal/mole) D + F <-> G + H ( $\Delta$ G = -4.4 kcal/mole)

Do the equations below represent coupled reactions? If not,why not? A + B <-> C + D ( $\Delta$ G = -5.4 kcal/mole) E + F <-> G + H ( $\Delta$ G = +4.4 kcal/mole)

In the reaction A + B <-> C + D,how might the reaction take place in the cell if the $\Delta$ G is very positive? How might the reaction occur if the $\Delta$ G is slightly positive?