CHAPTER 9

An anabolic reaction usually

requires energy

Anabolic pathways

All of the above are correct.

Oxidation reactions in biological systems generally involve

loss of electrons and hydrogen ions.

A phosphoanhydride bond

All of the above are correct.

Consider the following list of phosphorylated compounds with their free energies of phosphate hydrolysis:

Glucose-1-phosphate: -5.0 kcal/mol
PEP: -14.8 kcal/mole
ATP: -7.3 kcal/mol

Which of these molecules could phosphorylate an unknown compound whose free energy of phosphate hydrolysis is -10.3 kcal/mol?

PEP only

Cells can store energy in each of the following molecules except

Cells can store energy in all of the above molecules

NAD⁺

is a coenzyme acceptor of electrons and a hydrogen ion.

Which of the following is a coenzyme?

All are coenzymes.

Oxygen is toxic to

obligate anaerobes.

Which of the following statements best describes the role of NAD⁺/NADH in glycolysis?

NAD⁺ accepts electrons.

Each of the following can be the final electron acceptor in bacterial aerobic or anaerobic respiration except

pyruvate

The gross output of ATP from glycolysis is ________, whereas the net output of ATP is ________.

4; 2

Consider the three phases of glycolysis:

(1) preparation and cleavage (Gly-1 to Gly-5)
(2) oxidation (Gly-6 to Gly-7)
(3) pyruvate formation (Gly-8 to Gly-10)

Which of these phases produces ATP?

2 and 3

Which glycolytic enzyme uses ATP to phosphorylate glucose?

hexokinase

In the first step of glycolysis, glucose can be phosphorylated to glucose-6-phosphate, because

a phosphoanhydride bond has higher energy of hydrolysis than is required for formation of a phosphoester bond

Glucose transported into human cells can be transformed into all of the following except

sucrose for energy production.

Pyruvate can be a substrate or product involved in each of the following except

Pyruvate can be involved in all of the above.

Which of the following is not a product of fermentation?

glycogen

Positron emission tomography (PET) of a patient who has consumed the radiotracer fluorodeoxyglucose reveals tumors because

cancer cells accumulate fluorodeoxyglucose because they consume excessive amounts of glucose through aerobic glycolysis.

Each of the following is a substrate for glycolysis except

All are substrates for glycolysis.

The process of gluconeogenesis converts pyruvate or lactate into

glucose.

Three of the ten glycolysis enzyme reactions are not simply reversed in gluconeogenesis and require different enzymes because

these three glycolytic steps are the most highly exergonic and thermodynamically difficult to reverse

Isotopic labeling of a specific substrate carbon with ¹³C, which has an extra neutron, is particularly useful for investigating biochemical pathways because

the position of the labeled carbon can be traced through products of the pathway to characterize the pathway reactions

In animal cells, glycolysis and gluconeogenesis are regulated to ensure that both processes are reciprocally active. This regulation involves each of the following compounds except

NADH.

Allosteric regulation of key enzymes in glycolytic and gluconeogenesis pathways may involve each of the following except

binding of the allosteric regulator molecule to directly compete with substrate binding in the enzyme active site.