Chapter 9.6

Question 1

What are the three important substrates for gluconeogenesis

Answer 1

1) Glycerol 3-phosphate(from stored fats, or triacylglycerols)
2) Lactate(anaerobic glycolysis)
3) Glucogenic amino acids(from muscle proteins)

Question 2

What are the two classification of amino acids

Answer 2

-Glucogenic or ketogenic

Question 3

What are glucogenic amino acids

Answer 3

-they are amino acids that can be converted into intermediates that can be used in gluconeogenesis

• these are all amino acids except leucine and lysine
• > these intermediates can be fed into gluconeogenesis

Question 4

What are ketogenic amino acids

Answer 4

• they are amino acids that can be converted into ketone bodies
• > ketone bodies are alternatives to glucose, particularly during periods of prolonged starvation

Question 5

What is pyruvate carboxylase activated by? What is its funciton

Answer 5

• it is activated by acetyl coA

- >it converts pyruvate to oxaloacetate

Question 6

How does oxaloacetate move out of the mitochondria into the cytoplasm

Answer 6

• it needs to be reduced into malate

- >once outside in the cytoplasm, malate is again oxidized to oxaloacetate

Question 7

What is phosphoenolpyruvate carboxykinase induced by? What is its role

Answer 7

• it is induced by glucagon and cortisol

- it converts oxaloacetate to phosphoenolpyruvate in a reaction that requires GTP

Question 8

What is the role of fructose-1,6-biphosphatase?

Answer 8

• it is the rate limit step of gluconeogenesis

- takes fructose-1,6-biphosphate and then converts it to fructose-6-phosphate

Question 9

What inhibits and activates fructose-1,6-biphosphatase

Answer 9

• ATP activates it

- AMP and fructose 2,6-biphosphate inhibit it

Question 10

Where is glucose-6-phosphatase only found

Answer 10

• it is only found in the lumen of ER liver cells

- it is transported into the ER and free glucose is transported back into the cytoplasm

Question 11

Is glucose-6-phosphatase present in skeletal muscle

Answer 11

• no

- >therefore, muscle glycogen cannot serve as a source of blood glucose and it is only for use within th emuscle

Question 12

What is the role of glucose-6-phosphatase

Answer 12

-to convert glucose-6 phosphate to glucose

Question 13

What is hepatic gluconeogenesis dependent upon

Answer 13

• it is dependent on the Beta-oxidation of fatty acids

- therefore, glucose produced by the liver does not represent an energy source for the liver

Question 14

Can acetyl coA be converted to glucose? If not, then what fuel source is used in its place

Answer 14

• acetyl coA can be converted to ketone bodies

- >which can be used as a fuel source instead of glucose