Biology Exam 2

During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a ∆G of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the ∆G for the new reaction?

-20 kcal/mol

Asbestos is a material that was once used extensively in construction. One risk from working in a building that contains asbestos is the development of asbestosis caused by the inhalation of asbestos fibers. Cells will phagocytize asbestos, but are not able to degrade it. As a result, asbestos fibers accumulate in _____.

Lysosomes

A number of systems for pumping ions across membranes are powered by ATP. Such ATP-powered pumps are often called ATPases although they don't often hydrolyze 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?

ATPase activity must be pumping calcium from the cytosol to the SR against the concentration gradient

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

They require energy from ATP hydrolysis to break down polymers into monomers?

Chemical equilibrium is relatively rare in living cells because metabolic pathways are interconnected. Which of the following statements describes an example of a reaction that may be at chemical equilibrium in a cell?

a chemical reaction in which neither the reactant nor the products are being produced or consumed in any metabolic pathway at that time in the cell.

Which of the following types of reactions would decrease the entropy within a cell?

anabolic reactions

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

cofactor necessary for enzyme activity

HIV is the virus that causes AIDS. In the mid-1990s, researchers discovered an enzyme in HIV called protease. Once the enzyme's structure was known, researchers began looking for drugs that would fit into the active site and block it. If this strategy for stopping HIV infections were successful, it would be an example of what phenomenon?

competitive inhibition

A decrease in entropy is associated with which type of reaction?

dehydration

Which of the following would be the most appropriate method to observe the movements of condensed chromosomes during cell division?

standard light microscopy

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

the specific manner in which an enzyme binds substrate

Which of the following statements about anabolic pathways is true?

they consume energy to build up polymers from monomers