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Flashcards in Gluconeogenesis Deck (28)
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0

Average human uses around ___ g of Glucose per day

160

1

3 reactions that require different enzymes and processes from glycolysis

pyruvate to PEP
Fructose1,6 bis-phosphate to fructose 6 phosphate
Glucose 6 phosphate to glucose

2

three major carbon sources for Gluconeogenesis

Lactate
Amino acids
Glycerol

3

Lactate Dehydrogenase

converts lactate to pyruvate
producing NADH in process

4

Cori cycle

Shuttling of lactate from cells to only place, Liver, where it can be converted into Glucose

5

Two amino acids that do not participate/contribute to Gluconeogenesis

Lysine
Leucine

Amino acids are used to generate pyruvate

6

From fatty acids, Gluconeogenesis uses ...

the triacylglycerol portion only

7

Glycerol is used to make ...

DHAP

8

GNG occurs during fasting but also during ....

prolonged exercise
high protein diets
stress

9

Major substrates that stimulate GNG

Glycerol
Lactate
Amino acids - released from muscle when insulin levels are low, if from dietary protein then requires Low carb intake as well

10

Conversion of Pyruvate to PEP requires

Pyruvate dehydrogenase is inactive
Pyruvate carboxylase is active
PEPCK is induced

11

Induced vs. Activated enzymes

Activated - enzyme already made and it ready to be turned off/on

Induced - the enzyme needs to be made

12

Biochemically, Fasting leads to low insulin, adipose breaks down, elevated glucagon. The glucagon activates ...

Adenylate cyclase which converts ATP to cAMP
cAMP will induce the transcription of PEPCK which converts OAA to PEP
Fatty acids travel to liver and oxidation leads to acetylCoA, NADH and ATP leading to depletion of ADP which inhibits pyruvate dehydrogenase keeping pyruvate from going to the TCA cycle
Acetyl CoA activates pyruvate carboxylase

13

Under non fasting conditions, Epinephrine during stress...

activates adenylate cyclase

14

Glucagon phosphorylates pyruvate kinase to ...

inhibit the enzyme and stop the rxn from re-converting PEP back into pyruvate

15

High insulin during fasting leads

to an increase in F2,6 BP, while glucagon leads to a decrease in F2,6BP

16

F2,6BP activates

glycolytic enzyme, Phosphofructokinase
and it inhibits gluconeogenic enzyme F1,6BP

hence fasting leads to inhibition of kinase and activation of phosphatase

17

Glucokinase has high Km for glucose meaning ...

low affinity for glucose

18

Insulin ____ more GK

...

19


A patient comes in for a glucose tolerance test. 30 minutes after ingesting a high glucose beverage, which liver enzymes would be active?

Glucokinase and PFK1

20

what enzymes in the gluconeogenic pathway would be inhibited when the glycolytic pathway is activated?

PEPCK
Fructose 1,6 Biphosphate
pyruvate kinase
pyruvate carboxylase
glucose 6 phosphate

21

Hormonally, what does Fasting do?

decrease insulin and increase glucagon

22

what inhibits glycolysis and promotes gluconeogenesis?

Glucagon
cAMP
acetyl CoA

23

What does cAMP induce transcription of?

PEPCK
Acetyl CoA

these are breakdown products of fatty acid metabolism

which will activate pyruvate carboxylase

24

Fructose 2,6 Bisphosphate will ____ gluconeogenesis and ______ glycolsis

inhibit
promote

25

Describe the hormonal levels in the fed state

high insulin levels occur so glycolysis is favored and gluconeogenesis is inhibited

26

induced vs. active

induced means that enzyme needs to be made
active already made and ready to be turned on or off

27

what is the key starting ingredient for gluconeogenesis?

pyruvate which is formed lactate and amino acids