Gluconeogenesis

Question 1

What does the Cori Cycle do?

Answer 1

• the process of mobilizing glucose from lactate made in the muscles
• during long periods of exercise oxygen delivery to skeletal muscles is low, so anaerobic glycolysis happens and results in large amount of lactate
• lactate difuses into the blodostream and is carried to the liver where it becomes a substrate for gluconeogenesis
• the now synthesized glucose travels back to the muscles for more ATP production

Question 2

What is the rate limiting step of gluconeogenesis?

Answer 2

• conversion of fructose - 1,6 - bisphosphate to fructose-phosphate
• enzyme: fructose-1,6-bisphosphatase (removes a phosphate gorup)
• enzyme activity is tightly regulated
• glucagon increases activity (so speeds up gluconeogenesis)
• insulin decreases activity (slows down gluconeogenesis)

Question 3

What enzyme is needed for the last step of gluconeogenesis?

Answer 3

glucose-6-phosphatase
(lives in the ER)
- this enzyme remove phosphate from G-6-P to form glucose so that glucose can enter the bloodstream