13 - Glucose Metabolism

Question 1

what is gluconeogenesis?

Answer 1

pyruvate to glucose

using non carb sources

Question 2

where does gluconeogenesis occur most and least?

Answer 2

more - liver [as lactate arrives and converted to glu]

less - kidney [glucose not needed]

Question 3

what 3 things can act as precursors?

Answer 3

glycerol -> DHAP
lactate -> pyruvate
gluconeogenic amino acids

Question 4

no. of reversible steps in glycolysis and gluconeogenesis?

Answer 4

gly - 7

glu - 12

Question 5

what are the 3 non-reversible steps in glycolsis?

Answer 5

• pyruvate to phosenolpyruvate
• Fructose 1-6 Bisp to Fructose 6 Phosphate
• Glucose 6 phosp to Glucose

Question 6

how does gluconeo convert these steps?

Answer 6

pyruvate to phosenolpyruvate

• converts pyruvate to OXALO
• pyruvate carboxylase
• oxolo to phosphoenolpyruvate
• phosphoenolpyruvate carboxykinase

Fructose 1-6 BP to Fructose 6 P
- by Fructose 1-6 bisphophotase

Glucose 6 Phosphate to Glucose
- glucose 6 phosphotase

Question 7

how is lactaste converted to pyruvate?

Answer 7

by lactate dehydrogenase
NAD to NADH
in liver

Question 8

how is glycerol converted to DHAP?

Answer 8

glycerol to Glycerol 3 P first
- Glycerol Kinase

G3P to DHAP
- glycerol phosphate dehydrogenase

Question 9

pyruvate to oxaloacetate eq?

Answer 9

pyruvic acid + co2 + h2 = oxaloacetic acid + P
- pyruvate carboxylase
ATP

Question 10

oxaloacetate to phosphoenolpyruvate eq?

Answer 10

Oxaloacteic Acid = Phosphoenolpyruvate

- phosphoenolpyruvate carboxykinase

Question 11

fructose 1-6 BP to Fructose 6 phosphate eq?

Answer 11

F16BP = F6P

- fructose 1-6 bisphosphatse

Question 12

glucose 6 phosphate to glucose?

Answer 12

glucose 6 phosphate = glucose

- glucose 6 phosphotase

Question 13

reciprocal regulation: when will each pathway be activated?

Answer 13

energy needed

• glycol active
• gluco inactive

energy in excess

• glucon active
• gly inactive

Question 14

what is the signalling molecule that causes reciprocal reg?

Answer 14

Fructose 2,6 Bisphosphate

Question 15

which enzymes does Fructose 26 BP affect and how?

Answer 15

• stimulates phosphofructokinase
  [converts fructose 6 phosphate to fructose 1 6 bisphosphate]
  GLYCOL
• inhibits fructose 1-6 bisphosphatase [reverse] GLUCONEO

Question 16

what does a high level of PFK and Fructose 1-6bisphosphotase mean?

Answer 16

high PFK
- more glycolysis

high fructose 1-6 bisphosphotase
- more gluconeo

Question 17

what synthesises and breaks signalling mol Fructose 2-6 bisphosphate?

Answer 17

PFK2 makes it

Fructose Bisphosphotase 2 [FBase2] breaks it

Question 18

when F2-6BP is destroyed what does it become?

Answer 18

fructose 6 phosphate

Question 19

what occurs in low blood glucose levels?

Answer 19

glucagon increases
cAMP cascade activated
Protein Kinase A phosphorylated
FBPase 2 activated
PFK2 inhibited
so Fructose 26 BP broken down [decreases]
Gluconeogensis

Question 20

what occurs in high blood glucose levels?

Answer 20

insulin secreted
Activate PFK2
Inhibit FBase2
Increase Fructose 2-6 BP
Glycolysis

Question 21

why is glycogen storage useful?

Answer 21

• high glucose distrupts osmotic balance

- not osmotically active

Question 22

where is glycogen stored?

Answer 22

Liver

Question 23

structure of gluyocgen?

Answer 23

branched

1-4 and 1-6 glycosidic bonds

Question 24

how is glycogen broken down to give glucose?

Answer 24

glycogen
to
glucose 1 phosphate
[glycogen phosphorylase]

to
glucose 6 phosphate
[phosphoglucomutase]