chapter 8 metabolism

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Which of the following statements about enzymes is true?

Enzymes speed up the rate of the reaction without changing the ΔG for the reaction.

How does ATP drive mechanical work inside a cell?

binding to motor proteins

Which of the following statements is correct regarding ATP?

he energy in an ATP molecule is released through hydrolysis of one of the phosphate groups.

As ATP begins to build up in a cell, metabolism slows down. How does this happen?

ATP acts as an allosteric inhibitor to many of the enzymes involved in metabolism, thus slowing their function.

ATP is considered a renewable resource. What process makes this possible?

ATP can be regenerated by the addition of a phosphate group to ADP.

Which of the following correctly states the relationship between anabolic and catabolic pathways?

Anabolic pathways synthesize more complex organic molecules using the energy derived from catabolic pathways.

Which of the following statements correctly describes cofactors and coenzymes?

Both are nonprotein enzyme helpers; but most cofactors are metal ions, and coenzymes are organic molecules that are a specific type of cofactor.

How does ATP drive transport work inside a cell?

By phosphorylating a transport protein

If the entropy of a living organism is decreasing, which of the following is most likely to be occurring simultaneously?

Energy input into the organism must be occurring to drive the decrease in entropy.

The primary manner in which cells manage their energy resources in order to do work is called energy coupling. Which of the following statements accurately defines energy coupling?

Exergonic reactions drive endergonic reactions.

Which of the following is true regarding metabolic pathways?

Metabolic pathways consist of a series of reactions, each catalyzed by a different enzyme.

alue of ΔS be for a chemical reaction in which a molecule is broken down into smaller components

Positive

Which of these statements about enzyme inhibitors is true?

The action of inhibitors may be reversible or irreversible.

Which of the following statements about the active site of an enzyme is correct?

The active site may resemble a groove or pocket in the surface of a protein into which the substrate fits.

Which of the following is an example of the second law of thermodynamics as it applies to biological reactions?

The aerobic respiration of one molecule of glucose produces six molecules each of carbon dioxide and water.

Which of the following statements about ATP (adenosine triphosphate) is correct?

The cycling between ATP and ADP + Pi provides an energy coupling between catabolic and anabolic pathways.

What best characterizes the role of ATP in cellular metabolism?

The free energy released by ATP hydrolysis that may be coupled to an endergonic process via the formation of a phosphorylated intermediate.

The process of stabilizing the structure of an enzyme in its active form by the binding of a molecule is an example of

allosteric regulation

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

catabolic pathway

inhibitor has a structure that is so similar to the substrate that it can bond to the enzyme just like the substrate.

competitive inhibitor

Glucose + fructose → sucrose

endergonic

ATP allosterically inhibits enzymes in ATP-producing pathways. The result of this is called

feed back inhibition

Enzyme activity is affected by pH because

high or low pH may disrupt hydrogen bonding or ionic interactions and thus change the shape of the active site

inhibitor forms a covalent bond with an amino acid side group within the active site, which prevents the substrate from entering the active site or prevents catalytic activity.

irreversible

inhibitor binds to a site on the enzyme that is not the active site.

noncompetitive

An exergonic (spontaneous) reaction is a chemical reaction that

releases energy when proceeding in the forward direction

An exergonic reaction __________ free energy, and an endergonic reaction __________ free energy.

releases; absorbs

In general, the hydrolysis of ATP drives cellular work by

releasing free energy that can be coupled to other reactions


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