Cell bio ch. 9 Flashcards

The breakdown of glucose to pyruvate by a cell is an example of a(n) ________ reaction.

A. synthesis

B. catabolic

C. anabolic

D. amphibolic

E. aerobic

An energy-liberating pathway is considered to be

A. catabolic.

B. hydrogenation.

C. metabolic.

D. anabolic.

E. all of the above

A phosphoanhydride bond

Check all that apply.

has a standard free energy of hydrolysis of -7.3 kcal/mol.

is broken by hydrolysis.

is a high-energy bond.

The negatively charged phosphates of ATP influence one another by

A. resonance hybridization.

B. relative hydration.

C. dehydrogenation.

D. charge repulsion.

E. all of the above

Which of the following best describes the special "high-energy" bond of ATP?

A. hydrogenation

B. ionic

C. hydrogen

D. phosphoester

E. phosphoanhydride

Which term best describes the nitrogenous base adenine plus the sugar ribose?

A. adenine

B. adenosine triphosphate

C. adenosine diphosphate

D. adenosine

E. adenosine diphosphate followed by adenine or adenosine

Three hypothetical phosphorylated compounds (A, B, and C) are involved in energy metabolism. Standard free energies of hydrolysis for A = 13.1 kcal/mol, for B = -2.7 kcal/mol, and for C = 6.7 kcal/mol.
What is the sequence in which these molecules could most exergonically phosphorylate?

A. B, C, A

B. A, B, C

C. C, B, A

D. A, C, B

E. C followed by A or B

Oxidation in biological systems is usually accompanied by

A. dehydrogenation.

B. resonance stabilization.

C. repulsion.

D. hydrogenation.

E. all of the above

Which of the following is true of NAD⁺?

A. It is a coenzyme.

B. It represents the reduced form of niacin.

C. It serves as an electron source for biological oxidation.

D. It is derived from vitamin E.

E. It releases an adenosine to become NADH.

All of the following are coenzymes except

A. FAD.

B. NADP.

C. pyruvate dehydrogenase.

D. NAD.

E. coenzyme A.

Oxygen is toxic to

A. strict aerobes.

B. facultative anaerobes.

C. aerotolerant organisms.

D. strict anaerobes.

E. all of the above

During the first phase of glycolysis, ATP is used to form what type of bond with glucose?

A. substrate-level phosphorylation

B. phosphoanhydride

C. hydrogenation

D. phosphoester

E. dehydrogenation

The enzyme ________ is associated with the cytoplasmic portion of the glucose transporter.

A. hexokinase

B. glucose phosphorylase

C. hexose phosphorylase

D. gluconase

E. none of the above

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

A. 6; 4

B. 2; 1

C. 4; 2

D. 2; 4

E. 4; 1

In glycolysis, the product(s) of the enzyme aldolase is (are)

A. dihydroxyacetone phosphate and glyceraldehyde-3-phosphate.

B. dihydroxyacetone phosphate.

C. beta-hydroxy carbonate.

D. beta-hydroxy carbonate and dihydroxyacetone phosphate.

E. glyceraldehyde-3-phosphate.

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

A. NADH is capable of pumping ions during glycolysis.

B. NADH is used primarily in substrate-level phosphorylation.

C. NAD⁺ is used to carry electrons.

D. NADH is used to produce energy by directly creating the phosphoanhydride bonds in ATP.

E. all of the above

Glycolysis is divided into three phases. In which phase of glycolysis is ATP not generated?

A. 1

B. 2

C. 3

D. 1 and 2

E. 1, 2, and 3

How many enzymatic steps are involved in converting glucose to pyruvate?

A. 3

B. 6

C. 8

D. 10

E. 12

The enzyme used to break down fructose-1,6-bisphosphate into two trioses is called

A. enolase.

B. triose phosphate isomerase.

C. aldolase.

D. phosphoglucoisomerase.

E. hexokinase.

In glycolysis, which of the following molecules is oxidized to form 1,3-bisphosphoglycerate?

A. glucose-6-phosphate

B. glyceraldehyde-3-phosphate

C. glucose

D. 2-phosphoglycerate

E. 3-phosphoglycerate

Which glycolytic enzyme uses ATP as a substrate?

A. hexokinase

B. triose phosphate isomerase

C. alcohol dehydrogenase

D. phosphoglucoisomerase

E. aldolase

At which enzymatic step of glycolysis is water a product?

A. 3

B. 5

C. 6

D. 9

E. 10

Both the phosphorylation of intermediates and the formation of ATP in glycolysis are examples of

A. aerobic phosphorylation.

B. substrate-level phosphorylation.

C. anabolic phosphorylation.

D. oxidative phosphorylation.

E. product-level phosphorylation.

In the first step of glycolysis, glucose can be phosphorylated because

A. a phosphoanhydride bond has higher energy of hydrolysis than a phosphoester bond.

B. the transfer of a phosphate from ATP to glucose is exergonic.

C. both the number 2 and 3 carbons can be spontaneously phosphorylated.

D. the ketosugar is rapidly phosphorylated at the carbon 1 hydroxyl group.

E. a phosphoanhydride bond has higher energy of hydrolysis than a phosphoester bond and the transfer of a phosphate from ATP to glucose is exergonic.

Glucose is transported in the bloodstream to cells in all parts of your body. In cells, glucose has four main fates. Which of the following is not one of those fates?

A. Glucose is catabolized to carbon dioxide and water.

B. Glucose is converted to lactate.

C. Glucose is converted to acetyl CoA to make body fat.

D. Glucose is transformed into sucrose.

E. Glucose is used to synthesize glycogen.

Which of the following is not a fate of pyruvate within a cell?

A. gluconeogenesis

B. fermentation

C. alanine biosynthesis

D. anaerobic respiration

E. none of the above

During strenuous exercise, you may notice that your muscles burn. Which of the following statements best explains this phenomenon?

A. ADP is accumulating, which produces a burning sensation.

B. Proteins are being digested to provide energy.

C. Carbon dioxide is building up in muscle and changing the pH.

D. Pyruvic acid causes muscle pain.

E. Without oxygen, pyruvate is being converted to lactic acid.

Pyruvate is the end-product of glycolysis. Many organisms, such as anaerobic bacteria, can only produce energy by glycolysis; therefore, pyruvate has no more potential for ATP generation for these organisms. Rather than simply excrete pyruvate, this molecule is changed to another molecule such as lactate. In these organisms, why is pyruvate changed to lactate and excreted, rather than simply excreted?

A. Substrate level phosphorylation changes pyruvate to lactate.

B. Electrons (and protons) are added to pyruvate to make lactate.

C. NAD⁺ is regenerated as pyruvate is changed to lactate.

D. Pyruvate export requires more energy than lactate.

E. Electrons (and protons) are added to pyruvate to make lactate and NAD⁺ is regenerated as pyruvate is changed to lactate.

Which of the following is not a product of fermentation?

A. lactate

B. NAD⁺

C. sucrose

D. CO₂

E. ethanol

The purpose of the fermentation process is the

A. production of novel compounds, such as inorganic acids.

B. generation of additional energy in the form of ATP.

C. generation of additional reducing equivalents.

D. regeneration of NAD⁺.

E. all of the above

The process of glucose synthesis is called

A. glucogenesis.

B. aglycolysis.

C. gluconeogenesis.

D. glycolysis.

E. gluconeogenesis and glucogenesis.

Within animal cells, glycolysis and gluconeogenesis must not occur at the same time. Therefore, regulation is important. Which of the following molecules is least important in the regulation of glycolysis and gluconeogenesis?

A. ATP/ADP

B. phosphofructokinase-2

C. fructose-2,6-bisphosphate

D. acetyl CoA

E. NADH

Which of the following is not an allosteric inhibitor of an enzyme in the glycolytic pathway?

A. fructose-2,6-bisphosphate

B. citrate

C. acetyl CoA

D. ATP

E. glucose-6-phosphate

All of the following are directly used as alternative substrates for glycolysis except

A. mannose.

B. ribose.

C. fructose.

D. galactose.

E. galactose and ribose.

A key regulator of both glycolysis and gluconeogenesis is

A. alanine.

B. hexokinase.

C. fructose-2,6-biophosphate.

D. coenzyme (CoA).

E. glyceraldehyde-3-phosphate.

The breakdown of glucose to pyruvate by a cell is an example of what type of reaction?

A. anabolic

B. aerobic

C. apoptotic

D. synthetic

E. catabolic

An anabolic reaction usually

A. yields energy.

B. decreases molecular order.

C. requires energy.

D. is degradative, regardless of energy change.

E. involves no change in energy.

Anabolic pathways

A. increase molecular order.

B. can be stimulated by anabolic hormones.

C. are endergonic.

D. decrease entropy.

E. All of the above are correct.

Oxidation reactions in biological systems generally involve

A. addition of electrons and hydrogen ions.

B. loss of electrons and either addition or loss of hydrogen ions.

C. loss of electrons and hydrogen ions.

D. loss of electrons and addition of hydrogen ions.

E. addition of electrons and loss of hydrogen ions.

Much of the suitability of ATP as an energy intermediary is related to the instability of the bonds between the phosphate groups. These bonds are unstable because __________.

A. they are hydrogen bonds, which are only about 10% as strong as covalent bonds

B. the valence electrons in the phosphorus atom have less energy on average than those of other atoms

C. the phosphate groups are polar and are attracted to the water in the interior of a cell

D. the negatively charged phosphate groups vigorously repel one another

A phosphoanhydride bond

A. is a high-energy bond.

B. is broken by hydrolysis.

C. links two phosphate groups.

D. has a standard free energy of hydrolysis of - 7.3 kcal/mol.

E. All of the above are correct.

The negatively charged phosphates of ATP influence one another by

A. resonance destabilization.

B. positron emission.

C. standard free energy.

D. charge repulsion.

E. All of the above are correct.

The ATP "high-energy" or "energy-rich" bonds are which of the following types of bond?

A. phosphoanhydride

B. hydrogen

C. phosphoester

D. ionic

E. monophosphate

Which of the following is a coenzyme?

A. NADP

B. CoA

C. FAD

D. NAD

E. All are coenzymes.

Oxygen is toxic to

A. facultative organisms.

B. obligate aerobes.

C. obligate anaerobes.

D. cancer cells.

E. All of the above.

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

A. NADH accepts electrons during fermentation.

B. NAD⁺ accepts electrons.

C. NADH is used to directly create the phosphoanhydride bonds in ATP.

D. NADH is used primarily in substrate-level phosphorylation.

E. All of the above are correct.

How many NADH are produced by glycolysis?

A. 4

B. 5

C. 1

D. 3

E. 2

In glycolysis, ATP molecules are produced by _____.

A. photophosphorylation

B. oxidative phosphorylation

C. photosynthesis

D. substrate-level phosphorylation

E. cellular respiration

Which of these is NOT a product of glycolysis?

A. pyruvate

B. FADH₂

C. NADH

D. ATP

In glycolysis, what starts the process of glucose oxidation?

A. ATP

B. NADPH

C. FADH₂

D. hexokinase

E. ADP

In glycolysis there is a net gain of _____ ATP.

A. 3

B. 2

C. 1

D. 4

E. 5

Which of the following accurately summarizes the substrate-level phosphorylation strategy of ATP synthesis in glycolysis?

A. Electrons are transported through a series of carriers to reduce substrates and drive the phosphorylation of ADP to ATP.

B. Phosphate groups are transferred exergonically from high-energy phosphorylated intermediates to ADP to make ATP.

C. Electrons and hydrogen atoms are transferred to NAD⁺, which then transfers a phosphate to ADP to make ATP.

D. Energy from the sun is used to create a proton gradient that is used by an ATP synthase to phosphorylate ADP to ATP.

Which of the following accurately accounts for why gluconeogenesis is NOT simply the reverse of glycolysis?

A. Gluconeogenesis makes more ATP than glycolysis, so it is endergonic.

B. Three steps of glycolysis are highly exergonic and require different enzymes to reverse.

C. Gluconeogenesis is reciprocally and oppositely regulated with glycolysis.

D. Gluconeogenesis has too many steps.

During the first phase of glycolysis, phosphate forms what type of bond with glucose?

A. phosphoanhydride

B. hydrogen

C. diphosphate

D. phosphoester

E. ionic

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?

A. 1

B. 2

C. 3

D. 1 and 2

E. 2 and 3

How many enzymes are involved in glycolysis of glucose to pyruvate?

A. 8

B. 12

C. 3

D. 6

E. 10

Aldolase breaks down fructose-1,6-bisphosphate into two trioses that are

A. different and each doubly phosphorylated.

B. identical.

C. each doubly phosphorylated.

D. different and each singly phosphorylated.

E. identical and each doubly phosphorylated.

Which glycolytic enzyme uses ATP to phosphorylate glucose?

A. alcohol dehydrogenase

B. hexokinase

C. pyruvate kinase

D. phosphoglucoisomerase

E. aldolase

The phosphate group that is removed from PEP when it becomes pyruvate

A. is added to NAD⁺ to make NADP.

B. is added to glyceraldehyde-3-phosphate to make 1,3-bisphosphoglycerate.

C. is added to ADP to make ATP.

D. is added to fructose-6-phosphate to make fructose-1,6-bisphosphate.

E. is released as Pi.

During the conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate and phosphoenolpyruvate, a phosphate group is added to ADP to generate ATP. The mechanism for ATP production in this reaction is

A. substrate-level phosphorylation.

B. aerobic phosphorylation.

C. product-level phosphorylation.

D. anabolic phosphorylation.

E. oxidative phosphorylation.

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

A. glycogen for energy storage.

B. sucrose for energy production.

C. lactate in the absence of oxygen.

D. acetyl CoA to make body fat.

E. carbon dioxide and water by aerobic respiration.

In muscle cells, fermentation produces _____.

A. pyruvate

B. carbon dioxide, ethanol, NADH, and ATP

C. carbon dioxide, ethanol, and NAD⁺

D. lactate and NAD⁺

E. lactate, NADH, and ATP

In fermentation _____ is reduced and _____ is oxidized.

A. NAD⁺ ... pyruvate

B. lactate ... NADH

C. lactate ... ethanol

D. NADH ... lactate

E. pyruvate ... NADH

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

A. aerobic glycolysis.

B. gluconeogenesis.

C. fermentation.

D. amino acid biosynthesis.

E. Pyruvate can be involved in all of the above.

A temporary oxygen deficit during strenuous exercise causes a muscle to

A. synthesize glycogen.

B. switch to aerobic glycolysis.

C. ferment pyruvate to lactate.

D. synthesize muscle proteins in response to steroid hormone stimulation.

E. synthesize more NAD⁺.

Although pyruvate is the end product of glycolysis and no more ATP is generated by fermentation of pyruvate to ethanol, yeast produce ethanol under anaerobic conditions because

A. electrons (and protons) are then added to ethanol to make lactate.

B. pyruvate export requires more energy than ethanol export.

C. pyruvate to ethanol fermentation decreases deleterious CO₂ levels.

D. transfer of electrons from NADH to pyruvate to make ethanol regenerates NAD⁺, which is necessary for new rounds of glycolysis to proceed.

E. glycolysis substrate-level phosphorylation changes pyruvate to ethanol.

Which of the following is not a product of fermentation?

A. lactate

B. ethanol

C. CO₂

D. NAD⁺

E. glycogen

Fermentation directly

A. initiates gluconeogenesis.

B. regenerates NAD⁺ from NADH.

C. regenerates NADH from NAD⁺.

D. produces acetyl CoA.

E. generates ATP.

Each of the following is a substrate for glycolysis except

A. lactose.

B. galactose.

C. fructose.

D. mannose.

E. All are substrates for glycolysis.

The process of gluconeogenesis converts pyruvate or lactate into

A. mannose.

B. gluconate.

C. sucrose.

D. glucose.

E. fructose.

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

A. all three steps require hydrolysis of ATP for gluconeogenesis.

B. these three glycolytic enzymes cannot catalyze the reaction in the reverse direction under any circumstances.

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

D. NAD⁺ needs to be generated from NADH at each of these three steps.

E. these three glycolytic enzymes are not present in the cells performing gluconeogenesis.

Mannose, galactose, and fructose all enter glycolysis at either the first or the third step of the pathway. Which of the following accurately states the advantage of this design?

A. This allows for more ATP to be made per sugar.

B. This allows for the sugars to be converted into glucose.

C. This prevents the buildup of lactate.

D. This allows the metabolism of these sugars to be regulated.

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

A. AMP.

B. NADH.

C. acetyl CoA.

D. cAMP.

E. fructose-2,6-bisphosphate.