Topic A4

Question 1

Gluconeogenesis

Steps

Answer 1

Se egne notater

Question 2

Gluconeogenesis

Entry of different substrates

Answer 2

• Synthesis of glycogen from noncarbohydrate precursors
• Glucogenic amino acids
• Glycerol
• Lactate
• Proionate (in ruminants)
• (Pyruvate)

Question 3

Gluconeogenesis

Location

Answer 3

• Liver
• Kidney
• Partly cytoplasm
• Partly liver

Question 4

Gluconeogenesis

Regulation

Answer 4

Hormonal:

• Glucagon ⊕
• Insulin ⊖

Allosteric

• Fructose-1,6-phosphatase
  
  • Citrate ⊕
  • ATP ⊕
  • ADP ⊖
  • AMP ⊖
  • Fructose-2,6-P ⊖
• Pyruvate carboxylase
  
  • AcCoA ⊕
  • ADP ⊖
• Insulin stimulates production of fructose-2,6-P = ⊖ regulator of GNG
• Glucagon is opposite = ⊕ regulator of GNG

Question 5

Gluconeogenesis

Energy balance

Answer 5

• Glucose: ÷6 ATP
• Glycogen: ÷7 ATP

Question 6

Gluconeogenesis

Importance

Answer 6

• Fuel source for glucose dependent tissues:
  
  • Brain (ø glycogen reserves, blood glucose as primary fuel)
  • Testes
  • Nerves (ø glycogen reserves, blood glucose as primary fuel)
  • RBC (ø mitochondria for ATP production)
  • Kidney medulla
• Ruminants: takes place continously because of low blood sugar concentration
  
  • Main source: propionate
  • Nb. in early lactation