Gluconeogenesis Flashcards Preview

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Flashcards in Gluconeogenesis Deck (44)
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1
Q

Gluconeogenesis is _______ synthesis of glucose.

A

De novo

2
Q

Gluconeogenesis is synthesis of glucose form __________ substrates.

A

non-carbohydrate

3
Q

What are some of the non-carbohydrate substrates used in Gluconeogenesis.

A

Pyruvate
Glycerol from adipose tissue
glucogenic amino acids from muscle protein

4
Q

Enzymes for Gluconeogenesis are found where?

A

Only in liver, kidney, and intestinal epithelium

5
Q

Gluconeogenesis main occurs where?

A

Cytosol of liver cells

6
Q

During prolonged starvation what becomes the major glucose producing organs?

A

kidneys

7
Q

When glucose is not available what does the brain use for fuel?

A

ketones

8
Q

When does gluconeogenesis occur?

A

Durian fasting, starvation, or intense exercise

9
Q

Gluconeogenesis is highly ________. (energy requiring)

A

endergonic

10
Q

Can humans make glucose from acetyl CoA?

A

NO

11
Q

Glucokinase is replaced by which enzyme?

A

Glucose-6-phosphatase

12
Q

PFK is replaced by which enzyme?

A

Fructose-1,6-bisphosphatase

13
Q

Pyruvate kinase is replaced by which enzyme?

A

Pyruvate carboxylase and PEP carboxykinase

14
Q

What is the common substrate for gluconeogenesis?

A

Lactate/lactic acid

15
Q

Lactic acid is converted into _______ by which cycle?

A

pyruvate

Cori cycle

16
Q

What enzyme is used to convert lactate to pyruvate?

A

Lactate dehydrogenase

17
Q

What is the glucogenic amino acid that can convert to pyruvate?

A

alanine

18
Q

The Cori cycle comes at a net loss of how many ATP?

A

4

19
Q

What does the Cori cycle do?

A

Prevents lactic acid from building up in the muscles.

20
Q

The first step of gluconeogenesis occurs where?

A

mitochondrion

21
Q

The rest of gluconeogenesis (not 1st step) occurs where?

A

cytosol

22
Q

What enzyme converts pyruvate to oxaloacetate? This occurs where?

A

Pyruvate carboxylase

Mitochondrion (1st step)

23
Q

What is the essential coenzyme for the 1st reversal step? (pryruvate to oxaloacetate)?

A

biotin (B7)

24
Q

A biotin deficiency will cause what to build up resulting in excess production.

A

lactate

25
Q

What are allosteric activators of the 1st reversal step in gluconeogenesis?

A

ATP and Acetyl CoA

26
Q

What is the second part reversal?

A

Oxaloacetate to phosphoenolpyruvate

27
Q

What enzyme is used in the second step?

A

PEP carboxylase

28
Q

Where does the second step occur?

A

cytoplasm

29
Q

PEP carboxylase is facilitate by what?

A

Glucagon and cortisol

30
Q

Is lots of energy needed for step two reversal?

A

yes

31
Q

What is the rate limiting step of gluconeogenesis?

A

Step 3 reversal: fructose-6-phosphate from fructose 1,6-bisphosphate

32
Q

What is the enzyme for step 3 reversal?

A

Fructose 1,6- bisphosphatase

33
Q

What stimulates fructose 1,6-bisphosphase?

A

ATP and citrate

34
Q

What inhibits fructose 1,6–bisphosphatase?

A

AMP and fructose 2,6-bisphosphate

35
Q

What is the enzyme for step 1 glycolysis reversal?

A

Glucose-6 phosphatase

36
Q

What does glucose 6-phosphatase do?

A

coverts glucose 6-phophate into glucose

37
Q

Where is glucose 6-phosphatase located?

A

ER of liver and kidney cells

38
Q

G6P is ________ as it passes into the ER.

A

hydrolyzed

39
Q

Gluconeogenesis is inhibited by ______ and stimulated by _______.

A

insulin

glucagon

40
Q

Gluconeogenesis DOES NOT occur in _____ and the ____.

A

Muscles

brain

41
Q

Gluconeogenesis is an energy _______ process.

A

consuming

42
Q

How many ATP does gluconeogenesis use to produce one glucose molecule?

A

6

43
Q

Why is acetyl CoA not used to make glucose?

A

Requires more energy than using lactate or alanine

44
Q

If the glucose made is not used immediately, then what happens to it?

A

Converted and stored as glycogen in liver or skeletal muscle.