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Biochemistry > Chapter 15: Glucose Catabolism > Flashcards

Chapter 15: Glucose Catabolism Flashcards

1
Q

converts glucose to
two C3 units (pyruvate)

A

Glycolysis

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2
Q

do notes on slide 1

A
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3
Q

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

A

Hexokinase

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4
Q

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

A

isozymes

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5
Q

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

A

0.1 mM

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6
Q

Blood glucose concentration Km values

A

is 4 to 5 mM

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7
Q

hexokinase IV

A

Glucokinase

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8
Q

Glucokinase has a Km value of

A

2-5 mM

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9
Q

does Glucokinase work in high levels of glucose

A

yes

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10
Q

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

A

Muscle hexokinases I and II

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11
Q

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

A

those catalyzed by hexokinase,

phosphofructokinase

pyruvate kinase

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12
Q

Is the Major Flux-Controlling Enzyme of Glycolysis in Muscle

A

Phosphofructokinase

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13
Q

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

A

Phosphofructokinase

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14
Q

acts as an allosteric inhibitor

A

ATP

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15
Q

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

A

PFK

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16
Q

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

A

[AMP]

[ADP]

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17
Q

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

A

adenylate kinase reaction

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18
Q

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

A

denylate kinase reaction

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19
Q

The most potent allosteric effector of PFK

A

F2

6P

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20
Q

synthesize and degrade 2,3-BPG

A

Erythrocytes

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21
Q

how 2,3-BPG is synthesize and degrade

A

a detour from the glycolytic pathway .

22
Q

regulates hemoglobin’s oxygen affinity

A

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

23
Q

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

A

inherited defects of glycolysis in
erythrocytes

24
Q

Under aerobic conditions what happens to pyruvate

A

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

25
Q

Under anaerobic conditions what happens to pyruvate

A

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

26
Q

in muscle how pyruvate is reduced to lactate

A

lactate dehydrogenase (LDH)

27
Q

to regenerate NAD+ in a process known as

A

homolactic fermentation

28
Q

pyruvate is decarboxylated to yield what

A

CO2 and acetaldehyde

29
Q

what is CO2 and acetaldehyde reduced by

A

NADH

30
Q

what does CO2 and acetaldehyde yield

A

NAD+ and ethanol

31
Q

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

A

alcoholic fermentation

32
Q

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

A

lactate

33
Q

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

A

lactate produced in skeletal muscle cells

34
Q

what is lactate used to synthesize

A

glucose

35
Q

The muscle fatigue and soreness it is due to

A

acidity of lactate

36
Q

Anaerobic fermentation results in the production of

A

2 ATP per glucose

37
Q

oxidative phosphorylation yields up to

A

32 ATP per glucose

38
Q

anaerobic glycolysis yields up to

A

100 times faster than that of oxidative phosphorylation

39
Q

has a sweeter taste than sucrose and is inexpensive to produce

A

Fructose

40
Q

One possible hazard of excessive
fructose intake

A

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

41
Q

galactose is reduced

A

galactitol

41
Q

is treated by a galactose-free diet

A

Galactosemia

41
Q

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

A

Galactosemia

42
Q

require NADPH in addition to A TP

A

endergonic reactions

42
Q

uses the free energy of metabolite oxidation to synthesize ATP

A

NADH

43
Q

uses the free energy of metabolite oxidation for reductive biosynthesis.

A

NADPH

44
Q

how is NADPH is generated

A

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

45
Q

what is another name for pentose phosphate pathway

A

hexose monophosphate shunt

46
Q

required for several reductive processes in addition to biosynthesis

A

NADPH

47
Q

erythrocytes require a plentiful supply of

A

glutathione (GSH)

47
Q

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

A

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

48
Q

resistance to the malarial parasite,

A

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

Biochemistry (17 decks)

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