Chapter 15: Glucose Catabolism

Question 1

converts glucose to
two C3 units (pyruvate)

Answer 1

Glycolysis

Question 2

do notes on slide 1

Question 3

is a ubiquitous, relatively nonspecific enzyme that catalyzes the phosphorylation of hexoses such as D-glucose, D-mannose, and D-fructose.

Answer 3

Hexokinase

Question 4

enzymes that catalyze the same reaction but are encoded in different genes

Answer 4

isozymes

Question 5

Hexokinases I, II, and III have Km values of about what

Answer 5

0.1 mM

Question 6

Blood glucose concentration Km values

Answer 6

is 4 to 5 mM

Question 7

hexokinase IV

Answer 7

Glucokinase

Question 8

Glucokinase has a Km value of

Answer 8

2-5 mM

Question 9

does Glucokinase work in high levels of glucose

Answer 9

yes

Question 10

are allosterically inhibited by their product which happens at high cellular concentration of glucose 6-phosphate

Answer 10

Muscle hexokinases I and II

Question 11

the three reactions of glycolysis that function with large negative free energy changes in heart muscle under physiological conditions

Answer 11

those catalyzed by hexokinase,

phosphofructokinase

pyruvate kinase

Question 12

Is the Major Flux-Controlling Enzyme of Glycolysis in Muscle

Answer 12

Phosphofructokinase

Question 13

plays a central role in control of glycolysis because it catalyzes one of the pathway’s rate-determining reactions.

Answer 13

Phosphofructokinase

Question 14

acts as an allosteric inhibitor

Answer 14

ATP

Question 15

is a tetrameric enzyme with two conformational states, R and T .

Answer 15

PFK

Question 16

In muscle, [ATP] is ~50 times greater than [AMP] and ~10 times greater than [ADP].

Answer 16

[AMP]

[ADP]

Question 17

a metabolic signal consisting of a decrease in [A TP] too small to relieve PFK inhibition is amplified significantly by what?

Answer 17

adenylate kinase reaction

Question 18

which increases [AMP] by an amount that produces a much larger increase in PFK activity.

Answer 18

denylate kinase reaction

Question 19

The most potent allosteric effector of PFK

Answer 19

F2

6P

Question 20

synthesize and degrade 2,3-BPG

Answer 20

Erythrocytes

Question 21

how 2,3-BPG is synthesize and degrade

Answer 21

a detour from the glycolytic pathway .

Question 22

regulates hemoglobin’s oxygen affinity

Answer 22

The level of available 2,3-bisphosphoglycerate (2,3-
BPG)

Question 23

alter the ability of the blood to carry
oxygen as is indicated by the oxygen-saturation curve of its hemoglobin.

Answer 23

inherited defects of glycolysis in
erythrocytes

Question 24

Under aerobic conditions what happens to pyruvate

Answer 24

the pyruvate is completely oxidized via the citric acid cycle to CO2 and H2O

Question 25

Under anaerobic conditions what happens to pyruvate

Answer 25

pyruvate must be converted to a reduced end product in order to reoxidize the NADH produced by the GAPDH reaction

Question 26

in muscle how pyruvate is reduced to lactate

Answer 26

lactate dehydrogenase (LDH)

Question 27

to regenerate NAD+ in a process known as

Answer 27

homolactic fermentation

Question 28

pyruvate is decarboxylated to yield what

Answer 28

CO2 and acetaldehyde

Question 29

what is CO2 and acetaldehyde reduced by

Answer 29

NADH

Question 30

what does CO2 and acetaldehyde yield

Answer 30

NAD+ and ethanol

Question 31

pyruvate is decarboxylated to yield CO2 and acetaldehyde, which is then reduced by NADH to yield NAD+ and ethanol. This process is known as

Answer 31

alcoholic fermentation

Question 32

can either be exported from the cell or converted back to pyruvate.

Answer 32

lactate

Question 33

is carried by the blood to the liver, where it is used to synthesize glucose

Answer 33

lactate produced in skeletal muscle cells

Question 34

what is lactate used to synthesize

Answer 34

glucose

Question 35

The muscle fatigue and soreness it is due to

Answer 35

acidity of lactate

Question 36

Anaerobic fermentation results in the production of

Answer 36

2 ATP per glucose

Question 37

oxidative phosphorylation yields up to

Answer 37

32 ATP per glucose

Question 38

anaerobic glycolysis yields up to

Answer 38

100 times faster than that of oxidative phosphorylation

Question 39

has a sweeter taste than sucrose and is inexpensive to produce

Answer 39

Fructose

Question 40

One possible hazard of excessive fructose intake

Answer 40

PFK-catalyzed step of glycolysis and thereby avoids a major metabolic control point.

Question 41

galactose is reduced

Answer 41

galactitol

Question 41

is treated by a galactose-free diet

Answer 41

Galactosemia

Question 41

is a genetic disease characterized by the inability to convert galactose to glucose.

Answer 41

Galactosemia

Question 42

require NADPH in addition to A TP

Answer 42

endergonic reactions

Question 42

uses the free energy of metabolite oxidation to synthesize ATP

Answer 42

NADH

Question 43

uses the free energy of metabolite oxidation for reductive biosynthesis.

Answer 43

NADPH

Question 44

how is NADPH is generated

Answer 44

the oxidation of glucose-6-phosphate via an alternative pathway to glycolysis

Question 45

what is another name for pentose phosphate pathway

Answer 45

hexose monophosphate shunt

Question 46

required for several reductive processes in addition to biosynthesis

Answer 46

NADPH

Question 47

erythrocytes require a plentiful supply of

Answer 47

glutathione (GSH)

Question 47

are particularly sensitive to oxidative damage, although clinical symptoms may be absent.

Answer 47

individuals who are deficient in glucose-6-phosphate dehydrogenase (G6PD)

Question 48

resistance to the malarial parasite,

Answer 48

individuals who are deficient in glucose-6-phosphate dehydrogenase (G6PD)