Exam 8: An Introduction to Metabolism

- The figure illustrates the energy states associated with the reaction A + B ↔ C + D. Which of the following in the figure would be the same in either an enzyme-catalysed or a noncatalysed reaction?

How might a change of one amino acid at a site, distant from the active site of an enzyme, alter the substrate specificity of an enzyme?

Rate of an enzyme-catalysed reaction as a function of varying reactant concentration, with the concentration of enzyme constant In the figure, why does the reaction rate plateau at higher reactant concentrations?

When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?

Which of the following statements is true of metabolism in its entirety in all organisms?

Which of the following statements describes a common characteristic of catabolic pathways?

A number of systems for pumping ions across membranes are powered by ATP. Such ATP-powered pumps are often called ATPases, although they do not often hydrolyse ATP unless they are simultaneously transporting ions. Because small increases in calcium ions in the cytosol can trigger a number of different intracellular reactions, cells keep the cytosolic calcium concentration quite low under normal conditions, using ATP-powered calcium pumps. For example, muscle cells transport calcium from the cytosol into the membranous system called the sarcoplasmic reticulum (SR). If a resting muscle cell's cytosol has a free calcium ion concentration of 10-7 while the concentration in the SR is 10-2, then how is the ATPase acting?

Rate of an enzyme-catalysed reaction as a function of varying reactant concentration, with the concentration of enzyme constant. For the enzyme-catalysed reaction shown in the figure, if the initial reactant concentration is 1.0 micromolar, which of these treatments will cause the greatest increase in the rate of the reaction?

Which of the following statements is true for all exergonic reactions?

________ is a regulatory mechanism in which the end product of a metabolic pathway inhibits an enzyme that catalyses an early step in the pathway.

Which of the following characteristics is most likely to be associated with an enzyme that catalyses two different chemical reactions?

Which of the following statements is an important consequence of the first law of thermodynamics for a living organism?

Which of the following statements about anabolic pathways is true?

Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as ________.

-Activity of various enzymes at various temperatures (a) and at various pH (b) Which curves on the graphs may represent the temperature and pH profiles of an enzyme taken from a bacterium that lives in a mildly alkaline hot springs at temperatures of 70°C or higher?

The relationship between catabolism and anabolism is most similar to the relationship between which of the following pairs of terms?

In a metabolic pathway, succinate dehydrogenase catalyses the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, a substance that resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the amount of succinate molecules to those of malonic acid reduces the inhibitory effect of malonic acid. Which of the following statements correctly describes the role played by molecules described in the reaction?

- The figure illustrates the energy states associated with the reaction A + B ↔ C + D. Which of the following represents the activation energy required for the enzyme-catalysed reaction in the figure?

Why is the ΔG of ATP hydrolysis in the cell about twice as great as the ΔG of ATP hydrolysis in a test tube under standard conditions?

Which of the following aspects of enzyme structure is best described by a clasping handshake analogy?