Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Medical Biochemistry > Gluconeogenesis > Flashcards

Gluconeogenesis Flashcards

You may prefer our related Brainscape-certified flashcards:
USMLE® Step 1 flashcards
1
Q

where are most of the enzymes for gluconeogenesis?

A

cytosol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

where is pryvate carboxylase found?

A

mitochondria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

why is the mitochondria needed in gluconeogenesis?

A

to use lactate, pyruvate and glucogenic aa as substrates for gluconeogenesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where is PEP carboxylase found?

A

mictochondria and cytosol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what ensures that glycolysis and gluconeogenesis won’t take place at the same time?

A

tight hormonal regulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are the irreversible steps of gluconeogenesis?

A

glucose 6-phosphatase

Fructose 1,6-bisphosphatase

pyruvate carboxylase
PEP carboxylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

where is glucose 6-phosphatase found

A

liver and kidney

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

where is glucose 6-phosphate generated?

A

gluconeogensis and glycogen degradation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what does glucogon activate at the same time?

A

gluconeogensis and glycogen degradation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what two pathways provide blood glucose during the first day of fasting?

A

gluconeogensis and glycogen degradation (most used blood glucose at beginning of fast = branched structure)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

when are liver glycogen levels remarkably reduced? totally depleted?

A

8 hours

24 hours fo fasting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

where do lactate and alanine come from

A

muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

how is lactate converted to pyrvuate?

A

using NAD+ to make NADH and use lactate dehydrogenase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

how do you convert alanine to pyruvate ?

A

alpha KG + glutarate

alanine aminotransferase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are the two enzymes needed for gluconeogenesis?

A

pyruvate carboxylase

PEP carboxylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

how is fructose 2,6 bisphosphate formed?

A

by the bifunctional enzyme when the insulin/glucagon ratio is high

17
Q

at high blood glucose levels, what happens to hepatic glycolysis?

A

favored and gluconeogenesis is inhibited

18
Q

what can the bifunctional enzyme do?

A

form fructose 2,6 bisP using PFK-2

degrade fructose 2,6-bisP using BPase

19
Q

how many proteins and how many genes does the bifunctional enzyme have?

A

1 and 1

20
Q

insulin leads to the dephosphroylation of bifunctional enzyme and does what?

A

form fructose 2,6-bisP = promotes glycolysis why? - PFK-2 is active

21
Q

what does glucagon do to the bifunctional enzyme?

A

phosphorylates it and degrades fructose 2,6 bisP and promotes gluconeogenesis –PFK-2 inactive!

22
Q

what is gluconeogenesis stimulated by?

A

glucagon and cortisol

23
Q

when liver glycogen stores are limited and once they are depleted, what is gluconeogenesis the sole provider for?

A

blood glucose

24
Q

why are glycogen degradation and glucoenogenesis going at the same time after eating? glucagon activate

A

hormonal control

25
Q

what inhibits gluconeogenesis in the liver?

A

fructose 2,6 bisP

26
Q

what substrates for gluconeogenesis are found in liver?

A

intermediates of glycolysis, lactate in the liver, glucogenic aa

27
Q

what substrates for gluconeogenesis are found in the blood?

A

new lactates from RBC and Cori cycle muscle
alanine and glutamine (urea cycle)
glycerol

28
Q

what are the energy requirements for gluconeogenesis?

A

2 pyruvate
4 ATP
2 GTP
2 NADH

29
Q

how many nitrogen does alanine give to the liver?

A

1

30
Q

how many nitrogen does glutamine give to the liver?

A

2

31
Q

what is the advantage of the Cori cycle?

A

allows for anerobic glycolysis in skeletal muscle and release of lactate into the blood without lactic acidosis because the lactate is used by the liver for gluconeogenesis

32
Q

what happens to pyruvate in the fed state when insulin is ruling?

A

its substrate for PDH and acetyl coA formation goes to TCA cycle

33
Q

what happens to pyruvate when glucagon is ruling in the fasting state?

A

pyruvate is substrate for pyruvate carboxylase – gluconeogenesis

34
Q

what is the purpose of lactate in the heart?

A

pryruvate is formed and is substrate for the PDH and acetyl coA is used for energy metabolism
big advantage - pyruvate is formed from lactate not glucose! - therefore blood glucose is saved

35
Q

since the heart always has enough ATP, what will be inhibited? why is this significant?

A

glycolysis and PFK-1 are inhibited by ATP
this saves glucose
heart perferes degrading fatty acids for energy - degradation of palmitate = 128 ATP!

36
Q

what specific aa can be used for gluconeogenesis and inhibits (at the same time) glycolysis in the liver at the PK level?

A

alanine

37
Q

what molecules is released during fasting into the blood and can be used donating carbon atoms for gluconeogenesis in the liver?

A

glycerol released from fat cells after lipolysis of the stored TAGs

38
Q

what substrates are mostly used for gluconeogenesis during starvation and where do they come from?

A

amino acids

low insulin levels and high cortisol levels leads to protein degradation in muscle – they mainly alanine and glutaine

Medical Biochemistry (17 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions