Endocrine - Gluconeogenesis

Question 1

What two parts/organs of the body require glucose for fuel?

Answer 1

Brain and erythrocytes

Question 2

Is gluconeogenesis a simple reversal of glycolysis?

Answer 2

No

Question 3

Where does gluconeogenesis take place?

Answer 3

Liver 90%

Kidney 10%

Question 4

What 4 enzymes are needed in gluconeogenesis to overcome the irreversible steps of glycolysis?

Answer 4

Pyruvate carboxylase
PEP carboxykinase
Fructose-1,6-bisphosphatase
Glucose-6-phosphatase

Question 5

What converts pyruvate to oxaloacetate? What does it require?

Answer 5

Pyruvate Carboxylase

ATP

Question 6

What converts Oxaloacetate to PEP? What does it require?

Answer 6

PEP carboxykinase

GTP

Question 7

Is PEP in glycolysis?

Answer 7

Yes, 2nd to last step

Question 8

What converts Fructose-1,6-bisphosphate to Fructose-6-phosphate?

Answer 8

Fructose-1,6-bisphosphatase

Question 9

What converts Glucose-6-phosphate to glucose?

Answer 9

Glucose-6-phosphatase

Question 10

Where does the conversion of pyruvate to Oxaloacetate occur? What does it require as a prosthetic group? Why

Answer 10

Mitochondria
Biotin
Needed to add CO2 (new carbon atom)

Question 11

What is pyruvate carboxylase reaction tightly regulated by?

Answer 11

Acetyl-CoA

Question 12

What is the purpose of the malate shuttle and aspartate shuttle?

Answer 12

To get oxaloacetate from inside mitochondria to cytosol

Question 13

When does the newly added CO2 get removed from oxaloacetate? Why was it added in the first place?

Answer 13

Gets removed by phosphoenolpyruvate carboxykinase

Needed temporarily so phosphate could be added

Question 14

What is the major control point of gluconeogenesis?

Answer 14

Fructose-1,6-bisphosphatase -> Fructose-6 phosphate

Irreversible reaction!

Question 15

Where is the enzyme that converts Glucose-6-phosphate to glucose located?

Answer 15

Endoplasmic reticulum

Question 16

What is the energy cost of 1 glucose molecule being made through gluconeogensis?

Answer 16

4ATP
2GTP
2NADH
=12ATP

Question 17

What two ways of regulating gluconeogenesis exist?

Answer 17

Allosteric (local)

Hormonal

Question 18

What stimulates PKF1 and inhibits Fructose-1,6-bisphosphatase?

Answer 18

AMP

Question 19

What inhibits PFK-1?

Answer 19

ATP, citrate

Question 20

What inhibits pyruvate kinase?

Answer 20

ATP and alanine

Question 21

What stimualtes PK?

Answer 21

Fructose-1,6-BP

Question 22

What two hormones regulate gluconeogensis in the lvier? How?

Answer 22

Insulin - inhibits gluconeogensis (stimulates glycolysis)

Glucagon - stimulates gluconeogensis (inhibits glycolysis)

Question 23

What is the intermediate in the control step of gluconeogenesis?

Answer 23

Fructose-2,6-bisphophate

Question 24

Is pyruvate kinase more active or less active phosphorylated?

Answer 24

LEss active

Question 25

What hormone helps dephosphorylate PK?

Answer 25

Insulin

Question 26

What hormone helps phosphorylate PK?

Answer 26

Glucagon

Question 27

What is the Cori cycle?

Answer 27

Cycle of lactate to liver and glucose to erythrocytes and muscle

Question 28

How does glycerol enter gluconeogenesis?

Answer 28

As DHAP (dihydroxyacetone phosphate)

Question 29

What cycle can propionyl-CoA enter? How?

Answer 29

TCA cycle

Converted to succinyl-CoA