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Biochemistry > gluconeogenesis > Flashcards

gluconeogenesis Flashcards

1
Q

brain depends on glucose as its primary fuel and _______ use glucose as their only fuel

A

red blood cells

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2
Q

whole body needs ______ grams of glucose per day

A

160

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3
Q

daily glucose requirement of brain

A

120 grams

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4
Q

glucose present in body fluids

A

20 grams

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5
Q

glucose readily available from glycogen

A

190 grams

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6
Q

direct glucose reserves are sufficient to meet glucose needs for about _____

A

1 day

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7
Q

gluconeogenesis is especially important during a longer period of

A

fasting or starvation

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8
Q

where does gluconeogenesis occur

A

liver and kidney

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9
Q

gluconeogenesis is the synthesis of glucose from

A

non-carbohydrate precursors

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10
Q

glucogenesis converts _______ into _______

A

pyruvate

glucose

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11
Q

major precursors of gluconeogenesis

A

lactate, amino acids, and glycerol

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12
Q

pyruvate carboxylase (PC) is a ________ enzyme

A

mitochondrial

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13
Q

other enzymes (besides PC) of gluconeogenesis is found in

A

cytoplasm

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14
Q

oxaloacetate (OAA), a product of PC, is transported to cytoplasm via

A

malate shuttle

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15
Q

rate-limiting step of gluconeogenesis

A

F1,6-BP –> F6P via fructose 1,6-bisphosphatase

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16
Q

free glucose from gluconeogenesis can leave _____ and enter ______

A

liver

blood

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17
Q

glucose 6-phosphatase is a gluconeogenesis enzyme located where

A

in the lumen of the ER

18
Q

a protein called ______ transports glucose 6-phosphate to ER

A

T1

19
Q

a protein called ______ transports inorganic phosphate back into cytosol

A

T2

20
Q

a protein called ______ transports glucose back to cytoplasm

A

T3

21
Q

gluconeogenesis “by-passes” the irreversible steps of glycolysis through 4 enzymes not present in glycolysis

A

pyruvate carboxylase

phosphoenolpyruvate carboxykinase (PEP carboxykinase)

Fructose 1,6-bisphosphatase

glucose 6-phosphatase

22
Q

gluconeogenesis makes ______ , it requires ______

A

glucose

ATP

23
Q

gluconeogenesis has ______ points of ATP/GTP consumption

A

3

24
Q

in glycolysis, what activates the rate limiting step (activates PFK)?

A

F-2,6-BP

AMP

25
Q

in glycolysis, what inhibits the rate limiting step (inhibits PFK)?

A

ATP

citrate

H+

26
Q

in gluconeogenesis, what activates the rate limiting step (fructose 1,6-bisphosphatase)?

A

citrate

27
Q

in gluconeogenesis, what inhibits the rate limiting step (fructose 1,6-bisphosphatase)?

A

F-2,6-BP

AMP

28
Q

in glycolysis, what activates pyruvate kinase?

A

F-1,6-BP

29
Q

in glycolysis, what inhibits pyruvate kinase?

A

ATP

alanine

30
Q

in gluconeogenesis, what activates pyruvate carboxylase?

A

acetyl CoA

31
Q

in gluconeogenesis, what inhibits pyruvate carboxylase

A

ADP

32
Q

in gluconeogenesis what inhibits phosphoenolpyruvate carboxykinase

A

ADP

33
Q

gluconeogenesis is favored when

A

blood glucose levels are low and glycogen stores are depleted

34
Q

glycolysis energy

use

yield

net yield

A

use: 2 ATP
yield: 4 ATP

net yield: 2 ATP/glucose oxidized

35
Q

gluconeogenesis energy

use

yield

net yield

A

use: 4 ATP, 2 GTP
yield: 0

net yield: 6 ATP equivalents/glucose synthesized

36
Q

insulin always stimulates a

A

phosphatase

37
Q

glucagon always stimulates a

A

kinase

38
Q

insulin stimulates phosphoprotein phosphatase –> ______ is activated –> ______ is stimulated and ______ is inhibited

A

PFK2

glycolysis

glucogenogenesis

39
Q

glucagon stimulates protein kinase A (PKA) –> ______ is activated –> ______ is inhibited and ______ is activated

A

fructose bisphosophatase 2 (FBPase2)

glycolysis

gluconeogenesis

40
Q

the concentration of fructose 2,6-BP, a signaling molecule that stimulates or inhibits glycolysis is controlled by a fi-functional enzyme with a kinase and phosphatase domains

A

phosphofructokinase 2 (PFK2) and fructose bisphosphatase 2 (FBPase2)

41
Q

the cori cycle:

lactate produced in skeletal muscle and red blood cells can be converted back to:

the pyruvate can enter the gluconeogenic pathway and regenerate:

A

pyruvate in the liver

glucose (which was the source of the lactate)

Biochemistry (32 decks)

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