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Glycogen Metabolism and Glycolysis

BIOCHM-SDSKFE

The polysaccharides glycogen and starch are both made up of polymers of glucose linked α-1,4 with α-1,6 branches.

In animal cells, the breakdown of endogenous glycogen is largely by phosphorolysis producing Glucose-1-P. The enzyme phosphoglucomutase converts Glucose-1-P to Glucose-6-P, which can enter glycolysis.

In contrast, the breakdown of dietary starch is by hydrolysis yielding free glucose which can then enter cells and glycolysis.

Use your understanding of glycolysis and the glycolytic template provided below to determine which of the following choices accurately describes the effect of a glucose equivalent produced by phosphorolysis versus hydrolysis on glycolysis.

M. Rumpho-Kennedy. Created for Albert.io. Copyright 2016. All rights reserved.

A

More ATP is expended on preparing a glucose equivalent produced by phosphorolysis (compared to hydrolysis) to enter glycolysis AND this results in a lower net yield of glycolytic ATP.

B

The net synthesis of ATP from glycolysis is the same from a glucose equivalent whether produced by phosphorolysis of glycogen or hydrolysis of starch.

C

Greater ${NADH}$ is produced in glycolysis from a glucose equivalent generated by phosphorolysis vs. hydrolysis.

D

A glucose equivalent produced by phosphorolysis yields a net 3 ATP from glycolytic breakdown, whereas a net 2 ATP would be generated by a glucose equivalent produced by hydrolysis.

E

A glucose equivalent produced by phosphorolysis yields a net 4 FAD from glycolytic breakdown, whereas a net 2 FAD would be generated by a glucose equivalent produced by hy​drolysis.