Met 1: Gluconeogenesis

Question 1

When does gluconeogenesis occur?

Answer 1

During fasting states (high glucagon, low insulin)

Question 2

In what tissues does gluconeogenesis occur?

Answer 2

Liver (mostly) and kidney (some)

Question 3

What are three inputs for gluoneogenesis?

Answer 3

1. Glycerol (from fatty acids)
2. Lactate
3. AA’s

Question 4

Describe the Cori Cycle

Answer 4

1. Muscles and RBC’s make lactate when there’s insufficient oxygen
2. Lactate travels through blood to liver
3. Liver converts Lactate -> Pyruvate -> Glucose via gluconeogenesis
4. Glucose travels back to muscle and RBC’s

Question 5

In gluconeogenesis, energy is invested in _______ (tissue type) and spent in ________ (tissue type).

Answer 5

In gluconeogenesis, energy is invested in the LIVER and spent in MUSCLE and RBC’s

Question 6

Why does gluconeogenesis only occur in the liver and kidneys?

Answer 6

Only the liver and kidneys have Glucose 6 Phosphatase

Question 7

Describe the conversion of Pyruvate to PEP

Answer 7

1. Pyruvate (3C) gets converted to OAA (4C)
   
   • by Pyruvate Carboxylase
   • this uses CO2 and ATP
2. OAA (4C) gets converted to PEP (3C)
   
   • by PEP Carboxykinase
   • This produces CO2 and uses GTP

Question 8

What is the effect of F26BP on gluconeogenesis?

Answer 8

• F26BP inhibits fructose-1,6-biphosphatase
  
  • this enzyme is needed to convert F16BP into F6P
• Thus downregulates gluconeogenesis

Question 9

What is the effect of acetyl-coA on gluconeogenesis?

Answer 9

• Pyruvate can become OAA or acetyl-coA
  
  • OAA is the gluconeogenesis route
  • acetyl-coA is the TCA cycle route
• If there’s a build-up of acetyl-coA, it means that TCA pathway is shut off
• So, Acetyl-coA turns on gluconeogensis
  
  • by activating pyruvate carboxylase