Sugar Metabolism

Question 1

Describe prepatory phase of glycolysis

Answer 1

Phosphorylation of glucose and its conversion to glyceraldehyde 3 phosphate

Question 2

Payoff phase of glycolysis

Answer 2

Oxidative conversion of glyceraldehyde 3 phosphate to pyruvate and coupled formation of ATP to NADH

Question 3

What are fates of pyruvate?

Answer 3

TCA cycle, LDH, fermentation, biosynthesis

Question 4

What are high energy enzymes used in gluconeogenesis to bypass pyruvate kinase?

Answer 4

Pyruvate carboxylase and PEP carboxykinase

Question 5

What is the cofactor uses in pyruvate carboxylase?

Answer 5

Biotin

Question 6

What does biotin do?

Answer 6

Adds Carboxyl group to pyruvate to make oxaloacetate

Question 7

What two molecules signal low energy?

Answer 7

AMP and ADP

Question 8

At high amounts of AMP what tissue favors glycolysis?

Answer 8

Muscle tissue

Question 9

At low AMP what tissue does not favor glycolysis?

Answer 9

Liver

Question 10

Which molecule is the transfer for reducing equivalents?

Answer 10

Malate

Question 11

What are the four bypass enzymes of gluconeogenesis?

Answer 11

Pyruvate carboxylase, PEP carboxykinase, F16BP, glucose 6 phosphotase

Question 12

What molecule inhibits F16BP?

Answer 12

AMP

Question 13

What converts oxaloacetate to PEP?

Answer 13

PEP carboxykinase

Question 14

If lactate is starting source for gluconeogenesis, is malate needed?

Answer 14

No it creates its own reducing equivalents in the cytosol and uses a isozyme of PEP carboxykinase in the mitochondria

Question 15

What is the net result of the pentode phosphate pathway?

Answer 15

2 NADPH, ribose 5 phosphate, co2 and two protons

Question 16

What inhibits PFK 1?

Answer 16

ATP, citrate

Question 17

What allosterically activates PFK1?

Answer 17

Fructose 26 Bisphosphate and amp

Question 18

Insulin leads to what kind of cascade?

Answer 18

Dephosphorylation

Question 19

Glucagon leads to what kind of cascade?

Answer 19

Phosphorylation

Question 20

What is the substrate for PFK2/FBPase2

Answer 20

Fructose 6 phosphate

Question 21

Xylulose 5 phosphate activates what metabolic pathway by stimulating which enzyme?

Answer 21

Glycolysis and PFK2/FBPase2

Question 22

In liver if glucagon goes up, what happens to pyruvate kinase?

Answer 22

It is phosphorylated and inhibited

Question 23

What inhibits Pyruvate Kinase?

Answer 23

ATP, Acetyl-CoA, long chain Fatty acids, alanine

Question 24

What is a phosphorylase?

Answer 24

Enzyme using inorganic phosphate to break a bond

Question 25

Glycogen phosphorylase makes what molecule?

Answer 25

Glucose 1 phosphate

Question 26

What hormone activates glycogen breakdown?

Answer 26

Epinephrine

Question 27

What are benefits to glycogen phosphorolysis?

Answer 27

Glucose 6 phosphate is made without ATP, 1 ATP is used in predatory phase of glycolysis, there is a net gain of 3 ATP for glycolysis

Question 28

What does phosphoglucomutase do?

Answer 28

Catalyzes glucose 1 phosphate to glucose 6 phosphate

Question 29

What is the difference in glycogen breakdown in liver and muscle?

Answer 29

In liver glycogen will put glucose in blood. In muscle it is used for glycolysis

Question 30

In the liver what enzyme is needed for glucose to leave the cell?

Answer 30

Glucose 6 phosphotase

Question 31

Which tissue has two forms of glycogen phosphorylase?

Answer 31

Muscle. Phosphorylase a is active. Phosphorylase b not as active

Question 32

cAMP activates which enzyme to stimulate glycogen breakdown in muscle?

Answer 32

PKA. Stimulates glycogen breakdown

Question 33

cAMPincreases in response to what hormones?

Answer 33

Epinephrine and glucagon

Question 34

When is glycogen synthase active?

Answer 34

When it is dephosphorylated

Question 35

When is glycogen synthase inactive?

Answer 35

When it is phosphorylated by GSK3