after first midterm- cho

Question 1

(slide 85)in fasted state
UTILIZATION OF STORED CARBOHYDRATE
IN THE POST-ABSORPTIVE STATE

Answer 1

blood glucose ↓ to below fasting level (regulation)
[↑ glucagon from α cells, Islets of Langerhan, pancreas]
↓
↓ glucose uptake into cells
↓
↑ glycogenolysis and gluconeogenesis
(↑ glucose output from liver)
[muscle glycogen breakdown, no response to ↑ glucagon]

Question 2

5. Glycogenolysis

Answer 2

glycogen → glu 1-P → glu 6-P → glu
- enzyme phosphorylase → break
glycogen bonds

Question 3

liver has which enzyme that the muscles do not

why?

Answer 3

liver contains glucose-6-phosphatase
The liver releases glucose to the blood to be taken
up by brain and active muscle. The liver
regulates blood glucose levels.
The muscle retains glucose 6-phosphate to be use
for energy. Phosphorylated glucose is not
transported out of muscle cells.

Question 4

phosphorilase b-

Answer 4

inactive- gets activated by atp to become phosphorilase a to turn glycogen into glucose 1 phosphate

Question 5

epinephrine and glucagon stimulate

Answer 5

glycogen breakdown

Muscle is responsive to epinephrine.
• Liver is responsive to glucagon and
somewhat responsive to epinephrine.
• Both signal a cascade of molecular
events leading to glycogen breakdown.

Question 6

fed state

Answer 6

High blood glucose levels = fed state;
insulin stimulates glycogen synthesis and
inhibits glycogen breakdown.

Question 7

fast state

Answer 7

• Glucagon = starved state; stimulates
glycogen breakdown, inhibits glycogen
synthesis.

Question 8

gluconeogenesis

Answer 8

glycolysis in reverse (sort of ? not the same enzymes)
- mainly in liver (kidney in starvation)
- Converts pyruvate and related three- and four-carbon
compounds to glucose
Substrates: glycerol
lactate (Cori cycle)
pyruvate
part (if not all) of C-skeleton of most AAs
(ie, loss of NH2 by trans- or de-amination)
Essentially reversal of glycolysis except
that three reactions in glycolytic sequence
are not reversible: reactions catalyzed by
glucokinase and hexokinase,
phosphfructokinase, and pyruvate kinase
- GNG requires these reactions to be
bypassed by other enzymes

Question 9

Glycolysis Enzyme
Glucokinase
Phosphofructokinase-1
Pyruvate kinase
GNG Enzyme
Glucose 6-phosphatase
Fructose 1,6-bisphosphatase
Phosphoenolpyruvate
carboxykinase
Pyruvate carboxylase
(2 step reaction)

Answer 9

enzyme difference- dont memorise the enzymes it just shows that its difference and that GNG cant happen in every cell

Question 10

glycerol comes from

Answer 10

fat

Question 11

lactate comes from

Answer 11

muscles