BCCB2002 Lecture Notes - Lecture 3: Glycogen, Insulin, Endoplasmic Reticulum
Document Summary
Substrates of gng: glucogenic amino acids converted to. Converted to glucose if gng is predominating in a cell: lactate. Importance of lactate as a substrate for gng: from rbc. Only source of energy for rbc is atp from glycolysis, as it can(cid:495)t go. Lactate dehydrogenase (ldh) allows nad+ to be regenerated through tca or oxidative phosphorylation because it has no mitochondria pyruvate + nadh + h+ lactate + nad: fate of lactate. Leaves rbc and muscle cells to the liver, in which it can be converted back to pyruvate, which can then be converted to glucose via gng. Why gng can(cid:495)t be simply a reversal of glycolysis: 3 of the steps in glycolysis are irreversible. Different enzymes required to (cid:494)bypass(cid:495) the irreversible reactions. Irreversible steps are the steps that use atp. Three (cid:494)by-pass(cid:495) reaction steps in gng: pyruvate => phosphoenolpyruvate, pyruvate first transported into mitochondrial matrix via a transporter, enzyme pyruvate carboxylase. Coenzyme biotin, covalently attached via amide linkage.
