Gluconeogenesis

Question 1

What will be used to supply the bodies glucose when fasting for less than 24 hours?

Answer 1

Liver glycogen

Question 2

What supplies the body with glucose overnight?

Answer 2

Glycogenolysis and gluconeogenesis about equally

Question 3

What are the major tissues for gluconeogenesis?

Answer 3

Liver and kidney

Question 4

When does the kidneys contribution to gluconeogenesis become more important?

Answer 4

With starvation

Question 5

What are the noncarbohydrate for gluconeogenesis?

Answer 5

Glycerol
Glucogenic AA
Lactate
Propionate - minor in humans

Question 6

What are the three reactions that prevent gluconeogenesis from being a reversal of glycolysis?

Answer 6

Hexokinase
PFK-1
Pyruvate kinase

Question 7

How does gluconeogenesis bypass pyruvate kinase?

Answer 7

Changes pyruvate into oxaloacetate by pyruvate carboxylase
Changes oxaloacetate to phosphoenolpyruvate by PEP carboxylase

Question 8

What is required to change pyruvate to oxaloacetate?

Answer 8

ATP to ADP with Mg
Biotin
Mn
CO2
H2O

Question 9

Where does the reaction of pyruvate to oxaloacetate take place?

Answer 9

Mitochondria

Question 10

How is oxaloacetate transported from the mitochondria to the cytosol?

Answer 10

It is reduced to malate and reoxidized in the cytosol using NAD

Question 11

What is required to change oxaloacetate into phosphoenolpyruvate?

Answer 11

GTP to GDP
Produces CO2

Question 12

How does gluconeogenesis bypass PFK-1?

Answer 12

Fructose-1,6P to fructose 6P by fructose-1,6-bisphosphatase
Using H2O and resulting in a Pi

Question 13

How does gluconeogenesis bypass hexokinase?

Answer 13

Glucose-6P to glucose by glucose-6-phosphatase with H2O

Question 14

Where does the reaction catalyzed by glucose 6 phosphate take place?

Answer 14

Membrane of ER

Question 15

How many pyruvates are needed to make 1 glucose?

Answer 15

Two

Question 16

What is the energy investment needed for gluconeogenesis?

Answer 16

4 ATP
2 GTP

Question 17

How does glucagon affect gluconeogenesis through induction/repression?

Answer 17

Stimulates production of phosphoenolpyruvate carboxykinase and F1,6-bisphosphotase, thereby increasing gluconeogenesis
It also represses the transcription of enzymes used in glycolysis

Question 18

How do glucagon and epinephrine increase gluconeogenesis through phosphorylation?

Answer 18

Bind to g-protein, increasing concentration of cAMP. This activate cAMP dependent protein kinase which will phosphorylate PK and inactivate it.

Question 19

How does acetyl CoA affect gluconeogenesis?

Answer 19

It is an activator of pyruvate carboxylase and inhibits PDH

Question 20

What is an inhibitor of pyruvate carboxylase?

Answer 20

ADP

Question 21

What activates F1,6-bisphosphatase?

Answer 21

Citrate

Question 22

What inhibits F1,6-bisphosphatase?

Answer 22

AMP
F2,6 bisphosphate

Question 23

What AAs are not glucogenic?

Answer 23

Leucine
Lysine

Question 24

What is the Cori cycle?

Answer 24

Lactate produced in muscle is transported to liver and turned back into glucose. The glucose is released from the liver and returned to the muscles.

Question 25

Where does glycerol enter the pathway for either gluconeogenesis or glycolysis?

Answer 25

DHAP - dihydroxyacetone phosphate

Question 26

How is DHAP made from glycerol?

Answer 26

In liver and kidneys. Glycerol to glycerol phosphate by glycerol kinase using ATP. Glycerol phosphate to DHAP by glycerol phosphate DH using NAD

Question 27

What is required as a coenzyme to change propionate to succinyl CoA?

Answer 27

Vitamin B12

Question 28

How can raw egg whites affect gluconeogenesis?

Answer 28

They contain avidin which binds biotin preventing its absorption in the intestine. Biotin is needed for pyruvate carboxylase activity.

Question 29

How can alcohol inhibit gluconeogenesis?

Answer 29

Results in excessive NADH inhibiting FA oxidation. Favors pyruvate to lactate to make NAD, instead of gluconeogenesis pathway.

Question 30

Why can there be hypoglycemia in premature and LBW infants?

Answer 30

Little adipose tissue for FA oxidation Immature gluconeogenesis enzymes Inadequate stores of glycogen

Question 31

Why may there be hypoglycemia in an infant with a diabetic mother?

Answer 31

Hyperglycemia from mother leads to hyperplasia of pancreatic islet cells that produce more insulin - baby fails to suppress excessive insulin production after birth