Metabolic pathways: gluconeogenesis Flashcards
What is the definition of gluconeogenesis?
The synthesis of new glucose within the body from non-carbohydrate precursors
What precursors are involved in gluconeogenesis
Lactic acid/lactate - synthesised by skeletal muscle under anaerobic conditions
Amino acids - derived from muscle protein by proteolysis
Glycerol - derived from triglycerides by lipolysis in adipose tissue
Why is lactic acid produced by skeletal muscle under anaerobic conditions?
To re-oxidise NADH to NAD+
Where is the energy for gluconeogenesis derived?
Oxidation of fatty acids released from adipose tissue
Other than the oxidation of fatty acids stored in adipose tissue, where can the energy required from gluconeogenesis be derived?
Breakdown of protein stored in skeletal muscle
Where does gluconeogenesis occur?
Liver
Small amounts in kidneys
How many unique liver enzymes are required in gluconeogenesis to bypass the irreversible reactions involved in glycolysis?
4
Which TCA cycle intermediate is the first product in gluconeogenesis and where is it synthesised?
Oxaloacetate
Mitochondria
Why is oxaloacetate such an important intermediate in the TCA cycle?
Accepts acetyl groups from fat breakdown
How many pyruvates are needed to make one glucose molecule?
Two
How many ATP and GTP are required for gluconeogenesis?
6 (4ATP + 2GTP)
How is lactate transported to the liver?
Via the bloodstream
Where do amino acid precursors enter the gluconeogenic pathway?
Either:
Converted to pyruvate
Enter the TCA cycle (and are converted to oxaloacetate)
Which hormone - insulin or glucagon - signals for gluconeogenesis to occur?
Glucagon
Which hormone - insulin or glucagon - signals for inhibition of gluconeogenesis?
Insulin
