Glycogen breakdown and gluconeogenesis Flashcards Preview

Human Function- Exam 4 Material > Glycogen breakdown and gluconeogenesis > Flashcards

Flashcards in Glycogen breakdown and gluconeogenesis Deck (24):
1

how long do dietary carbs last?

3-4 hours

2

how long does glycogen last?

30 hours

3

where is gluconeogenesis done?

liver

4

where does energy between meals come from?

adipose triglycerides
muscle proteins if absolutely necessary

5

where is glycogen broken down?

liver and skeletal muscle

6

what does liver glycogen phophorylase do?

cleaves alpha 1,4 linkages by phophoryolysis, releasing 1 G-1-P at a time

7

what does debranching enzyme do?

rearranges the branch so that 1 glucose is left and then cleaves the alpha 1,6 link via hydrolysis, releasing free glucose

8

how much G-1-P is released? free glucose?

G-1-P 92%
free glucose 8%

9

what is the difference between liver and muscle glycogenolysis?

liver has glucose-6-phosphatase which cleaves G-6-P to free glucose which is released into the blood
liver does not

10

what does glucose-6-phosphatase do?

cleaves glucose-6-phosphate to free glucose

11

what is phosphoglucomutase?

isomerizes glucose-1-P to glucose-6-P

12

what is gluconeogenesis?

making glucose

13

what are the 3 irreversible steps of glycolysis that have to be bypassed during gluconeogenesis? what do they do?

hexokinase- changes free glucose to glucose-6-phosphate
phophofructokinase- phophorylates fructose-6-phosphate
pyruvate kinase- changes PEP to pyruvate, releasing ATP

14

how are the 3 irreversible steps of glycolysis bypassed?

pyruvate carboxylase
PEP carboxylase
fructose-1,6-bisphophatase
liver glucose-6-phosphatase

15

what are the 4 requirements for gluconeogenesis? where do they come from?

NADH
energy
Acetyl CoA
Carbons
everything except carbons comes from fatty acid oxidation

16

what is the energy cost of gluconeogenesis?

4 ATP
2 GTP

17

can carbons from acetyl CoA be used in gluconeogenesis?

No- pyruvate dehydrogenase is not reversible

18

how can fatty acids be used to make glucose?

odd chains are broken down into propinyl-CoA, a 3 carbon compound that can be converted to succinyl-C-A (TCA cycle intermediate, which can form oxaloacetate via TCA cycle

19

what is DHAP? where can it come from? what is it used for?

dihydroxyacetone phophate
made from glycerol, fructose
used as a carbon substrate for gluconeogenesis

20

what happens in glycogen storage diseases?

glycogen can't be broken down so it accumulates in cells
due to issues in glycogen breakdown, gluconeogenesis, or fatty acid oxidation

21

what is Von Gierke's disease?

deficiency in liver glucose-6-phosphatase- can't change G6P to free glucose
symptoms- severe hypoglycemia due to lack of glycogenolysis and gluconeogenesis
cannot be helped by galactose or fructose

22

what are the 3 glycogen storage diseases

Von Gierke's
Hers Disease
McArdles

23

what is Hers Disease?

deficiency in liver glycogen phosphorylase
symptoms- milder hypoglycemia (gluconeogenesis works)
can be treated with fructose or galactose

24

what is McArdle's Disease?

deficiency in muscle glycogen phophorylase
symptoms: none, only muscle glycogen can't be used