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synthesis of lipids glycolysis citric acid cycle
7. (7 pts) If glucose-6-phosphate is labeled with radioactive 14C isotope at
its C3 position,
where will the label appear in pyruvate? DRAW pyruvate and CIRCLE the 14C.
Question 18. (5 pts) Use numbers to indicate the order of steps in the pyruvate
Decarboxylation of pyruvate to an aldehyde
Regeneration of the oxidized FAD cofactor
Formation of acetyl CoA
Oxidation of aldehyde to the level of a carboxylic acid
Reoxidation of the lipoamide cofactor
Question 19. (3 pts) We can measure the rate of reaction for some dehydrogenases by
measuring changes in the absorbance of the reaction mixture at 450nm in a
spectrophotometer. What molecule is changing in absorbance in this reaction? Circle
the correct choice.
glucose ( FAD)
Question 20. (8pts, 2pts each) We can store glucose as polymer called glycogen in
the liver and muscles. We use several enzymes to release glucose monosaccharides
for use by our cells. Answer the following questions about glycogen breakdown:
a) What is the enzyme that removes 1 glucose subunit from the nonreducing end of
b) The enzyme in part a is not a hydrolase, because it adds what molecule to glucose to
make glucose 1-phosphate?
c) In order to enter glycolysis, the glucose 1-phosphate is then converted to what
glucose 6- phosphate
d) What type of enzyme catalyzes the reaction in part c?
hexokinase aldolase dehydrogenase
Question 21. (8 pts, 4 pts each) Draw the structures of the two products of the enzyme
in gluconeogenesis that replaces the glycolytic enzyme phosphofructokinase (2nd
-O - P .
" NO PHZON
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- Spring '11
- Exam #3