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Exam 6: Energy and Metabolism

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Question 1

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A particular chemical reaction is exergonic.What can you say about the relationship between the reactants and the products in this exergonic reaction?

A) The reactants have more free energy than the products
B) The reactants are likely more disordered and the products are likely more ordered
C) The reactants cannot spontaneously react to generate the products
D) The reactants likely have lower enthalpy than the products

E) B) and D)
F) B) and C)

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Question 2

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AMP-activated protein kinase (AMPK) is an enzyme that is activated by high levels of AMP in cells.If levels of AMP are high in cells, that means that levels of ATP are low.Once active, AMPK activates catabolic pathways and inhibits anabolic pathways in the cell.Why do you think that is the case? Choose the answer that best explains the role of AMPK.

A) High levels of AMP indicate that there is a high amount of energy stored in the cell, thus activating catabolic pathways and inhibiting anabolic pathways are mechanisms to use stored energy.
B) By inhibiting anabolic pathways, AMPK provides a mechanism to generate heat for the cell, which is important if AMP levels are high in the cell.
C) By activating catabolic pathways, AMPK provides a mechanism to activate exergonic pathways, which is important if AMP levels are high in the cell.
D) Activating catabolic pathways and inhibiting anabolic pathways will ultimately lead to higher consumption of ATP, which is important if AMP levels are high in the cell.

E) A) and B)
F) A) and C)

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Question 3

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Tacrolimus (FK-506) is a drug that inhibits an enzyme called calcineurin.Calcineurin is a protein phosphatase.This is an enzyme that dephosphorylates (removes phosphate groups) from proteins.When added to cells, tacrolimus can inhibit the dephosphorylation of a protein called NFAT, but it cannot prevent the dephosphorylation of a protein called CDK1.What is the most likely explanation for this finding?

RNA molecules that also act as enzymes are given the name

Glucose is converted into glucose 6-phosphate by hexokinase.Glucose 6-phosphate then serves as the substrate for the enzyme phosphoglucose isomerase, which converts this reactant into fructose 6-phosphate.Fructose 6-phosphate serves as the substrate for phosphofructokinase, which converts fructose 6-phosphate into fructose 1,6-bisphosphate.Based on the information provided, this is an example of what?

The Law of Thermodynamics that states that increases in entropy are favored is:

While standing at the top of the stairs, you have a potential energy of 40 Joules.If you walk all the way down the stairs, what would your potential energy be at the bottom of the stairs?

A ribozyme catalyzes a reaction on itself and actually changes shape.This is an example of.

The chemistry of living systems representing all chemical reactions is called

You are working with a specific enzyme-catalyzed reaction in the lab.You are a very careful experimentalist, and as a result, at the beginning of each of your experiments, you measure the temperature in the lab.On days 1 through 5, the temperature in the lab was 20^oC.Today is day 6 of your experiment, and the temperature in the lab is 30^oC.How do you predict that this will alter the rate of your enzyme-catalyzed reaction?

In the hypothetical biochemical pathway, P $\rightarrow$ Q + R $\rightarrow$ S $\rightarrow$ T, which step is likely to have evolved first?

You return home to find that your baby brother has scattered his toy trains and trucks all over the floor of your room.As you begin to pick up the toys and put them away, you realize that even though he is just a baby, he has clearly mastered:

A current problem in modern medicine is the development of drug resistance mutations.This occurs when a mutation arises in a disease-causing microbe making it resistant to a drug and thus rendering the drug useless in treating a specific disease.Many useful drugs are competitive inhibitors of specific enzymes, and the drug-resistance mutations prevent the binding of the drug.These types of mutations, in addition to preventing competitive inhibitor binding, can also sometimes reduce the activity of the enzyme.Why is that the case? rev: 01_20_2015_QC_CS-4567

The organic non-protein components that aid in enzyme functioning are called

It is summer, and you are excited about going to your local amusement park, and specifically about riding the new roller coaster that was just built.You imagine waiting at the top of the stairs for the roller coaster to pull into the station, climbing into the car, strapping yourself into the seatbelt, and pulling down the harness.You can imagine the cars slowly chugging up to the top of the first hill, coming down on the other side, and the excitement you expect to feel as you go along for the ride.Of all of the things that you have imagined, which is an example of potential energy?

The energy needed to destabilize existing chemical bonds and start a chemical reaction is called

Phosphofructokinase (PFK) is an enzyme that converts fructose 6-phosphate to fructose 1,6-bisphosphate, by adding a phosphate group.This is the first committed step of the metabolic pathway of glycolysis, and thus it is very tightly regulated.AMP binds to PFK at a site distinct from the binding site for fructose 6-phosphate, and stimulates the formation of fructose 1,6-bisphosphate.ATP binds to PFK at a site distinct from the binding site for fructose 6-phosphate, and inhibits the formation of fructose 1,6-bisphosphate.There are other regulators of this enzyme as well.What is the role of AMP in this example?

Why do we have storage macromolecules, such as fats, in our bodies?

The term oxidation is derived from the name of the element oxygen.This is reasonable, because oxygen

A new antibiotic has been developed that inhibits the activity of an enzyme by competitive inhibition.What effect will this have on the activation energy of the enzyme-catalyzed reaction?