Chapter 8 BIOL 1107 – Flashcards

The process of cellular respiration, which converts simple sugars such as glucose into CO2 and water, is an example

energy is observed in two basic forms: potential and kinetic. Which of the following correctly matches these forms with a source of energy? the energy related to the height of a bird above the ground: kinetic energy the energy associated with a gradient of ions across a membrane: kinetic energy the covalent bonds of a sugar molecule: potential energy the motion of individual molecules: potential energy the heat released from a living organism: potential energy

which of the following is true of metabolism in its entirety in all organisms Metabolism manages the increase of entropy in an organism. Metabolism consists of all the energy transformation reactions in an organism. Metabolism uses all of an organism's resources. Metabolism depends on a constant supply of energy from food.

which of the following is an example of potential rather than kinetic energy water rushing over Niagara Falls light flashes emitted by a firefly a crawling beetle foraging for food a molecule of glucose

most cells cannot harness heat to perform work because

which of the following involves a decrease in entropy? condensation reactions reactions that separate monomers depolymerization reactions hydrolysis reactions

which term most precisely describes the cellular process of breaking down large molecules into smaller ones? metabolism anabolism (anabolic pathways) dehydration catabolism (catabolic pathways)

anabolic pathways

which of the following is a statement of the first law of thermodynamics The entropy of the universe is decreasing. Energy cannot be transferred or transformed. Energy cannot be created or destroyed. The entropy of the universe is constant

which of the following statements is representative of the second law of thermodynamics? Cells require a constant input of energy to maintain their high level of organization. Without an input of energy, organisms would tend toward decreasing entropy. Conversion of energy from one form to another is always accompanied by some gain of free energy. Every energy transformation by a cell decreases the entropy of the universe.

which of the following types of reactions would decrease the entropy within a cell? hydrolysis catabolic reactions digestion anabolic reaction

a chemical reaction that has a positive ΔG is best described as

choose a pair of terms that correctly completes this sentences Catabolism is to anabolism as _____ is to ______

in solution, why do hydrolysis reactions occur more readily than condensation reactions?

which of the following statements about the combustion of glucose with oxygen to form water and CO2 is correct? The entropy of the universe decreases as the result of this reaction. The free energy lost in this combustion is less than the energy that appears as heat. The reverse reaction, making glucose from water and carbon dioxide, must be an exergonic reaction. The entropy of the products is greater than the entropy of the reactants. This is the process of cellular respiration, an anabolic pathway that releases free energy.

Which part of the adenosine triphosphate molecule is released when it is hydrolyzed to provide energy for biological reactions?

which of the following statements about ATP is correct The cycling between ATP and ADP + Pi provides an energy coupling between catabolic and anabolic pathways. The energy release on hydrolysis of ATP is the result of breaking a high-energy bond. Almost all of the free energy released on the hydrolysis of ATP is released as heat. The hydrolysis of ATP is an endergonic process. The hydrolysis of ATP can supply energy needed for catabolic pathways.

Why is ATP an important molecule in metabolism?

Which of the following is most similar in structure to ATP? an RNA nucleotide a pentose sugar a DNA nucleotide an amino acid with three phosphate groups attached

Catabolic pathways _____.

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

When ATP releases some energy, it also releases inorganic phosphate. What happens to the inorganic phosphate in the cell?

The following reaction A --> B + C + heat is a(n) _____ reaction.

A(n) _____ reaction occurs spontaneously.

Which of these reactions requires a net input of energy from its surroundings?

In cells, what is usually the immediate source of energy for an endergonic reaction?

The reaction ADP + P --> ATP is a(n) _____ reaction.

The energy for an endergonic reaction comes from a(n) _____ reaction

What is the fate of the phosphate group that is removed when ATP is converted to ADP?

Select the INCORRECT association. enzyme ... protein kinetic energy ... motion potential energy ... positional energy exergonic ... spontaneous exergonic ... uphill

what is energy coupling?

What type of reaction breaks the bonds that join the phosphate groups in an ATP molecule?

In general, enzymes are what kinds of molecules?

Enzymes work by _____.

an enzyme

What name is given to the reactants in an enzymatically catalyzed reaction?

As a result of its involvement in a reaction, an enzyme _____.

Enzymes are described as catalysts, which means that they _____.

Which of the following would be unlikely to contribute to the substrate specificity of an enzyme? A positive charge on the substrate is attracted to a negative charge in the active site of the enzyme. The enzyme has the ability to change its configuration in response to the substrate binding. A hydrophobic group on the substrate interacts with several hydrophobic amino acids on the enzyme. A similar shape exists between a pocket on the surface of the enzyme and a functional group on the substrate. The enzyme has an allosteric regulatory site.

Which of the following is NOT a way in which an enzyme can speed up the reaction that it catalyzes? The active site of the enzyme can provide a microenvironment with a different pH that facilitates the reaction. Binding of the substrate to the active site can stretch bonds in the substrate that need to be broken. The active site can provide heat from the environment that raises the energy content of the substrate. The binding of two substrates in the active site provides the correct orientation for them to react to form a product. The enzyme binds a cofactor that interacts with the substrate to facilitate the reaction.

The binding of a compound to an enzyme is observed to slow down or stop the rate of the reaction catalyzed by the enzyme. Increasing the substrate concentration reduces the inhibitory effects of this compound. Which of the following could account for this observation? The compound is a competitive inhibitor. The compound reduces disulfide bonds, causing the enzyme molecules to partially unfold. The compound forms a covalent bond with one of the amino acid residues needed for enzyme activity. The compound causes a cofactor to be lost from the enzyme. The compound is a negative allosteric regulator.

Which of the following is true of enzymes? Enzyme function is independent of physical and chemical environmental factors such as pH and temperature. Enzyme function is increased if the 3- D structure or conformation of an enzyme is altered. Enzymes increase the rate of chemical reaction by lowering activation energy barriers. Enzymes increase the rate of chemical reaction by providing activation energy to the substrate.

The lock-and-key analogy for enzymes applies to the specificity of enzymes _____.

You have discovered an enzyme that can catalyze two different chemical reactions. Which of the following is most likely to be correct? Two types of allosteric regulation occur: The binding of one molecule activates the enzyme, while the binding of a different molecule inhibits it. The enzyme is subject to competitive inhibition and allosteric regulation. The enzyme contains α-helices and β-pleated sheets. Either the enzyme has two distinct active sites or the reactants involved in the two reactions are very similar in size and shape.

Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's _____.

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?

According to the induced fit hypothesis of enzyme catalysis, _____.

Increasing the substrate concentration in an enzymatic reaction could overcome which of the following? allosteric inhibition the need for a coenzyme insufficient cofactors competitive inhibition

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 noncompetitive inhibitor decreases the rate of an enzyme reaction by _____.

Succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the ratio of succinate to malonic acid reduces the inhibitory effect of malonic acid. Based on this information, which of the following is correct? Succinate dehydrogenase is the enzyme, and fumarate is the substrate. Succinate is the substrate, and fumarate is the product. Fumarate is the product, and malonic acid is a noncompetitive inhibitor. Succinate dehydrogenase is the enzyme, and malonic acid is the substrate.

Succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the ratio of succinate to malonic acid reduces the inhibitory effect of malonic acid. What is malonic acid's role with respect to succinate dehydrogenase? Malonic acid _____.

Consider a situation in which the enzyme is operating at optimum temperature and pH, and has been saturated with substrate. What is your best option for increasing the rate of the reaction?

You have added an irreversible inhibitor to a sample of enzyme and substrate. At this point, the reaction has stopped completely. What can you do to regain the activity of the enzyme?

You have an enzymatic reaction proceeding at the optimum pH and optimum temperature. You add a competitive inhibitor to the reaction and notice that the reaction slows down. What can you do to speed the reaction up again?

Which of the following statements about feedback regulation of a metabolic pathway is correct? The final product of a metabolic pathway is usually the compound that regulates the pathway. The enzyme that is regulated by feedback inhibition is usually the last enzyme in the metabolic pathway. The compound that regulates the pathway acts as a competitive inhibitor or a positive allosteric regulator. The products of the pathway become the reactants for a different reaction, and thus products are unable to accumulate. Accumulation of the product of the pathway increases further formation of that product.

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?

the mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is most precisely described as ____.

You have isolated a previously unstudied protein, identified its complete structure in detail, and determined that it catalyzes the breakdown of a large substrate. You notice it has two binding sites. One of these is large, apparently the bonding site for the large substrate; the other is small, possibly a binding site for a regulatory molecule. What do these findings tell you about the mechanism of this protein?

besides turning enzymes on or off, what other means does a cell use the control enzymatic activity

Protein kinases are enzymes that transfer the terminal phosphate from ATP to an amino acid residue on the target protein. Many are located on the plasma membrane as integral membrane proteins or peripheral membrane proteins. What purpose may be served by their plasma membrane localization?