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Ch 16

Terms in this set (35)

____________ is the principle carbohydrate in living systems.
Glucose

Intro
The product of aerobic glycolysis is ____________.
Pyruvate

Intro
____________: These organisms cannot survive in the presence of oxygen.
a) obligate anaerobes
16.2
The substance ____________ must be regenerated for glycolysis to proceed.
NAD+
The intermediate that is necessary for the conversion of galactose to glucose is ____________.
f) UDP-glucose
16.3
____________: This molecule is an allosteric inhibitor of phosphofructokinase.
ATP
16.4
The transporter that is responsible for fructose uptake in the intestine is ____________.
GLUT5
16.4
____________ is the enzyme responsible for converting galactose to be used in the glycolytic pathway.
galactokinase
16.3
____________ is the transporter found in the pancreas and liver.
GLUT2
16.4
An allosteric activator of glycolysis is ____________.
AMP
Glycolysis produces a net of ______________ moles of ATP per 1 mole of glucose.
Ans: 2 Section: 16.1
Glucose is the most stable hexose because the hydroxyl groups are all in the ______________position.
Ans: axial Section: Introduction
The key regulatory enzyme for glycolysis is ______________.
Ans: phosphofructokinase Section: 16.1
______________ are enzymes that catalyze the transfer of a phosphoryl group from ATP to an acceptor.
Ans: Kinase Section: 16.1
The regeneration of ______________ in the reduction of pyruvate to lactate sustains glycolysis under anaerobic conditions.
Ans: NAD+ Section: 16.2
In alcoholic fermentation, the decarboxylation of pyruvate requires a coenzyme that contains the vitamin ______________.
Ans: thiamine, or B1 Section: 16.2
A potent allosteric activator of liver phosphofructokinase is ______________, which is produced from fructose-6-phosphate by PFK2.
Ans: fructose-2,6-bisphosphate Section: 16.4
In the absence of oxygen, ______________ increases the expression of most glycolytic enzymes and the glucose transporters GLUT1 and GLUT3.
Ans: HIF-1, or hypoxia-inducible transcription factor Section: 16.4
The first irreversible enzymatic reaction unique to a metabolic pathway is called the ______________ step
Ans: committed Section: 16.4
______________ mediate the thermodynamically downhill movement of glucose across plasma membranes.
Ans: glucose transporters Section: 16.4
Which of the following is a reason that glucose is a common metabolic fuel used by living organisms?
A) It has a stable ring structure and is unlikely to glycosylate proteins.
B) It has been found as one of the monosaccharides formed under prebiotic conditions.
C) It is the only sugar used by the brain.
D) A and B.
E) A, B, and C.
D) A and B.

A) It has a stable ring structure and is unlikely to glycosylate proteins.
B) It has been found as one of the monosaccharides formed under prebiotic conditions.

Intro
What is the purpose of phosphorylating glucose in cytosol?
A) to trap glucose in the cell
B) to destabilize glucose and facilitate the next series of metabolic steps
C) to convert it to a more soluble form
D) All of the above.
E) A and B
E) A and B

A) to trap glucose in the cell
B) to destabilize glucose and facilitate the next series of metabolic steps

16.1
Which two 3-carbon molecules are generated by the cleavage of fructose-1,6-bisphosphate?
A) glyceraldehyde-3-phosphate and 3-phosphoglycerate
B) glyceraldehyde-3-phosphate and dihydroxyacetone phosphate
C) pyruvate and phosphoenolpyruvate
D) enolase and 2-phosphoglycerate
E) glyceraldehyde-3-phosphate and pyruvate
B) glyceraldehyde-3-phosphate and dihydroxyacetone phosphate

16.1
What is a common mechanistic feature of kinases?
A) Phosphoryl groups are transferred from AMP to an acceptor.
B) The binding of substrate induces cleft closing.
C) Kinases convert aldoses to ketoses.
D) All of the above.
E) None of the above.
B) The binding of substrate induces cleft closing.

16.1
What reaction is catalyzed by aldolase?
A) isomerization of DHAP to GAP
B) ligation of GAP and DHAP
C) reversible cleavage of F-1,6-BP to DHAP and GAP
D) cleavage of DHAP to GAP
E) irreversible aldol condensation of DHAP and GAP
C) reversible cleavage of F-1,6-BP to DHAP and GAP

16.1
What is the function of glyceraldehyde 3-phosphate dehydrogenase?
A) oxidation by NAD+ and the formation of acyl phosphate
B) oxidation of the alcohol to an aldehyde
C) dehydration and dephosphorylation of GAP
D) hydrolysis of GAP
E) None of the above.
A) oxidation by NAD+ and the formation of acyl phosphate

16.1
What is the function of a thioester intermediate such as the one formed from GAP?
A) It speeds up the actual reaction so that more product can be made.
B) The thioester shifts the equilibrium of the first stage of the reaction.
C) The thioester allows the two-step reaction to be coupled so the second reaction, the energetically unfavorable phosphorylation, can proceed.
D) The thioester intermediate induces a conformational change that alters the enzyme specificity.
E) The thioester prevents the formation of metabolically unfavorable side products.
C) The thioester allows the two-step reaction to be coupled so the second reaction, the energetically unfavorable phosphorylation, can proceed.

16.1
What is substrate-level phosphorylation?
A) phosphorylation of AMP by ATP
B) ATP synthesis when the phosphate donor is a substrate with high-phosphoryl-transfer potential
C) phosphorylation of glycolytic intermediates
D) phosphorylation of ATP coupled to an ion gradient
E) ATP and AMP synthesis from two molecules of ADP
B) ATP synthesis when the phosphate donor is a substrate with high-phosphoryl-transfer potential

16.1
What type of enzyme catalyzes the intramolecular shift of a chemical group?
A) hydrolase
B) kinase
C) dehydrogenase
D) mutase
E) None of the above.
D) mutase

16.1
What are the primary metabolic fates of pyruvate?
A) ethanol
B) lactate
C) acetyl CoA
D) All of the above.
E) None of the above.
D) All of the above.

A) ethanol
B) lactate
C) acetyl CoA

16.1 & 2
Fructose can enter glycolysis at two distinct points, depending on the tissue. How is fructose metabolized in adipose tissue?
A) Fructose is cleaved to two molecules of GAP.
B) Fructose is converted to fructose 1-phosphate.
C) Fructose is converted to fructose 6-phosphate.
D) Fructose is cleaved to GAP and DHAP.
E) Fructose is converted to glucose, which enters the pathway.
C) Fructose is converted to fructose 6-phosphate.

16.3
Lactose intolerance is caused by a deficiency of:
A) lactase.
B) elastase
C) lactose.
D) sucrase.
E) None of the above.
A) lactase.
16.3
How are the glycolytic enzymes regulated?
A) through transcriptional control
B) through reversible phosphorylation
C) through allosteric control
D) All of the above.
E) None of the above.
D) All of the above

A) through transcriptional control
B) through reversible phosphorylation
C) through allosteric control
16.4
Cancer-driven hypoxia brings about the induction of which genes involved in glycolysis?
A) GLUT3
B) hexokinase
C) aldolase
D) All of the above.
E) None of the above.
D) All of the above.
A) GLUT3
B) hexokinase
C) aldolase

16.4
During exercise, glycolysis is stimulated by a:
A) high-energy charge of the cell.
B) feed-forward stimulation of pyruvate kinase.
C) negative feedback inhibition on hexokinase.
D) A and C.
E) All of the above.
B) feed-forward stimulation of pyruvate kinase.

Intro
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