Exam 8: Energy, Enzymes, and Metabolism

Computer-based models aimed at simulating the different biochemical pathways in a cell are frequently used in

Refer to the figure below. Hexokinase catalyzes the reaction between glucose and ATP to form glucose 6-phosphate and ADP.The figure shows how the active site of hexokinase orients ATP for attack by glucose during the reaction.In the absence of enzyme, this reaction would be much slower because there would be a _______ number of orientations of the two substrates compared with the number of orientations provided by the enzyme.

Which statement about allosteric regulators is true?

Which statement about enzymes is true?

Chemical equilibrium

Refer to the figure and table below. The figure shows a metabolic pathway catalyzed by a series of enzymes labeled with numbers.The metabolite T was tested for inhibitory effects on each enzyme in the pathway, and the results are summarized in the table.The extent of inhibition is indicated by the number of plus signs.Lack of inhibition is indicated by a minus sign.Which statement gives a valid conclusion from these results?

Refer to the figure below. This cellular reaction is catalyzed by the enzyme triosephosphate isomerase.At equilibrium, the ratio of dihydroxyacetone phosphate to glyceraldehyde phosphate is 24:1.What changes in conditions in the cell will cause changes in the direction of flux through this reaction? Give two changes, one that will cause a change in flux in the forward direction, and a second that will cause change in the reverse direction.

Refer to the expression below. The enzyme alcohol dehydrogenase catalyzes this reaction in cells.The enzyme uses the coenzyme NAD⁺ in the reaction.Not shown are details about the active site, which contains a zinc ion that functions as a cofactor.How do the roles of cofactor and coenzyme compare in this particular case?

The process that involves an end product acting as an inhibitor of an earlier step in a metabolic pathway is called

In cells, multiple biochemical pathways are all interconnected and often run simultaneously.Which components determine the direction of flow through these diverse pathways?

Refer to the figure below. The enzyme catalyzing this reaction would be classified in the group of enzymes known as _______.

An effector molecule that binds to a site on an enzyme other than the active site and causes a conformational change in the enzyme is termed a(n) _______ regulator.

Competitive inhibitors of enzymes work by

End products of biosynthetic pathways often act to block the initial step in that pathway.This phenomenon is called

The activity of an enzyme was examined in the laboratory as it catalyzed the formation of a product molecule, B, from a substrate, A.This reaction was carried out in an aqueous solution consisting of water and copper sulfate at a pH of 7.While attempting to repeat the experiment, a biochemist uses a solution of pure distilled water (pH = 7) and observes that the rate of formation of B has decreased dramatically.Which is a possible explanation for this result?

Which type of reaction is used to break down ATP into ADP and P_i?

Knowing the change in free energy (G) of a reaction tells us

Which statement about the exergonic hydrolysis of maltose to glucose is true?

ATP can phosphorylate many different molecules.This means that ATP can

Phosphofructokinase catalyzes the first reaction in a pathway that commits the product to proceed through glycolysis, often called the first commitment step in glycolysis.Phosphofructokinase is also regulated so that the cell can quickly respond to its energy needs.Given this background information about phosphofructokinase, what is the most likely mode of inactivation of this enzyme when the cell needs to slow down or turn off glycolysis?