Gluconeogenesis Flashcards
Why do cells need to synthesise carbohydrates (4)?
Reserve materials (glycogen, starch), carbohydrate Miletus of glycoproteins and glycolipids (cell membranes), components of conductive tissue, cell wall materials (bacteria and plants)
What are the three places gluconeogenesis occurs?
Liver > kidney > intestines
What are the precursors for glucose?
Lactate and amino acids
What are the key precursors of gluconeogenesis in humans? (4)
Lactate (liver, kidney), glycerol (intestine), alanine (liver), glutamine (kidney, intestine)
What does the glyoxylate cycle do?
Allows fatty acids, acetate and acetyl CoA to form carbohydrates.
Why is gluconeogenesis required?
Because some cells have a high demand for glucose. Gluconeogenesis provides glucose
What are the three irreversible steps of glycolysis and what four enzymes are required to bypass them?
Glucose -> glucose-6-P (hexokinase/glucokinase); fructose-6-P (phosphofructokinase-1); phosphophoenolpyrovate -> pyruvate (pyruvate kinase)
How much energy is required for gluconeogenesis and how much is produced?
6 ATP/GTP, 2 ATP
Why is acetyl CoA not a gluconeogenic precursor in animals?
Because in animals acetyl CoA enters the TCA cycle and yields 2 CO2 with no net production of oxaloacetate or any other TCA intermediate
What is the fate of the two carbons of acetyl CoA that enter the TCA cycle?
It is used in the glyoxylate cycle
What are the two unique enzymes of the glyoxylate cycle and how do they allow for acetyl CoA to function as a precursor for gluconeogenesis?
Isocitrate lyase and malate synthase. The glyoxylate cycle consumes two acetyl CoA yielding succinate. This bypasses the oxidative decarboxylation steps of the TCA cycle
What are the end products of the glyoxylate cycle?
2 CoASH and a succinate
