Gluconeogenesis

Question 0

______ catalyzes the car-boxylation of pyruvate to oxaloacetate, an ATP-requir-ing reaction in which the vitamin biotin is the co-enzyme.

Answer 0

Mitochondrial pyruvate carboxylase

Requires biotin as cofactor

Question 1

is the term used to include all path-ways responsible for converting noncarbohydrate pre-cursors to glucose or glycogen

Answer 1

Gluconeogenesis

Question 2

A second enzyme, ______, catalyzes the decarboxy-lation and phosphorylation of oxaloacetate to phospho-enolpyruvate using GTP (or ITP) as the phosphatedonor. Thus, reversal of the reaction catalyzed by pyru-vate kinase in glycolysis involves two endergonic reac-tions.

Answer 2

phospho-enolpyruvate carboxykinase

Question 3

The conversion of fructose 1,6-bisphosphate to fructose6-phosphate, to achieve a reversal of glycolysis, is cat-alyzed by ______. Its presencedetermines whether or not a tissue is capable of synthe-sizing glycogen not only from pyruvate but also fromtriosephosphates. It is present in liver, kidney, andskeletal muscle but is probably absent from heart andsmooth muscle.

Answer 3

fructose-1,6-bisphosphatase

Question 4

most potent positive allosteric effector of phospho-fructokinase-1 and inhibitor of fructose-1,6-bisphos-phatase in liver is_____.

Answer 4

fructose 2,6-bisphosphate

Question 5

those which are theproducts of the metabolism of glucose in tissues. Thus,lactate, formed by glycolysis in skeletal muscle anderythrocytes, is transported to the liver and kidneywhere it re-forms glucose, which again becomes avail-able via the circulation for oxidation in the tissues. Thisprocess is known as the ______

Answer 5

Cori cycle, or lactic acid cycle

Question 6

Of the amino acids transported from muscle to theliver during starvation, alanine predominates. The _________ transports glucosefrom liver to muscle with formation of pyruvate, fol-lowed by transamination to alanine, then transportsalanine to the liver, followed by gluconeogenesis backto glucose.

Answer 6

glucose-alanine cycle

Question 7

Hexokinase has a low Km for glucose and in the liver issaturated and acting at a constant rate under all normalconditions. Glucokinase has a considerably higher Km(lower affinity) for glucose, so that its activity increasesover the physiologic range of glucose concentrations. True or false?

Answer 7

True