Gluconeogenesis

Question 1

Step 1

Answer 1

pyruvate to PEP: use two reactions

• pyruvate to oxaloacetate (pyruvate carboxylase)
• Oxaloacetate to PEP (PEP carboxykinase)

Question 2

Step 2

Answer 2

Fructose-1,6-bisPO4 to Fructose-6-PO4

fructose-1,6-biphosphatase

Question 3

Step 3

Answer 3

Glucose-6-PO4 to Glucose
(glucose-6-phosphatase)
Present in liver and kidneys while absent in muscle and adipose tissue.

Question 4

Importance of Pyruvate carboxylase

Answer 4

Major rate controlling enzyme in gluconeogenesis which requires biotin as a cofactor.
Functions in Mitochondria to produce OAA
Cannot pass though membrane, so must be changed to Malate or Aspartate.
Cytosolic Malate dehydrogenase reconverts OAA after it passes through membrane

Question 5

Regulation in Gluconeogenesis

Answer 5

• Induced by glucagon, epinephrine
• Induction suppressed by insulin
• Allosterically modified by acetyl CoA (+) and ADP (-)

Question 6

Gluconeogenic Substrates

Answer 6

Lactate –> Pyruvate
amino acids (alanine, etc…) –> pyruvate
glycerol –>DHAP (alpha triose-PO4) [DHAP is also a component of glycolysis

Question 7

Cori Cycle

Answer 7

Glucose becomes glycogen in the muscle which then converts to lactate which can be used in the liver. The lactate uses ATP from gluconeogenesis to create glucose which goes through the blood and back to the muscle for another lap in the cycle.