CHEM 153A Quiz: Week 8 SQ Part I Answers

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azuremammoth471

9 Jan 2019

School

UCLA

Department

Chemistry and Biochemistry

Course

CHEM 153A

Professor

Tienson

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Document Summary

Part i: hexokinase catalyzes the phosphorylation of glucose to form glucose-6-p in the first step of glycolysis. Briefly discuss the tissue location and role of this enzyme. Your answer should include the properties of the enzyme and how these properties are related to the function of the enzyme. Hexokinase phosphorylates glucose in all tissues preventing it from diffusing out of the cells when the. Briefly indicate the catalytic properties of the enzyme and its primary location in mammals. Briefly discuss the physiological role of this enzyme. Properties: high km (~ 10mm); not inhibited by g-6-p. Role: provide increasing production of g-6-p for glycogen synthesis when [glucose] is relatively high. Facilitates clearing glucose from the blood when [glucose] is too high: draw the structure of fructose-2,6-bisphosphate and briefly describe its role in controlling the rate of glycolysis. Diagram the formation and breakdown of fructose-2,6-bisphosphate, identify the enzyme(s) involved and how their activity is controlled.

Related Questions

1. All of the following are/can be products of the pentosephosphate pathway
EXCEPT?
a. NADPH
b. Reducing power
c. Precursor metabolites
d. Ribose 5-phosphate
e. ATP

2. Chelsea is working with the N2 (g)- fixing soil bacteriumAzotobacter. She hopes
to isolate two enzymes from this bacterium: hexokinase and
phosphoglycerokinase. Try as she might, Chelsea cannot isolatehexokinase but
she is incredibly successful in isolating phosphoglycerokinase. Ina sudden
moment of brilliance, Chelsea realizes that this is because
a. hexokinase is a triose-stage enzyme.
b. Azotobacter degrades glucose using the Entner-doudoroff pathwayrather
than the Embden-Meyerhof pathway.
c. Azotobacter cannot degrade organic carbon.
d. hexokinase and phosphoglycerokinase are the same enzyme.

3. After coming to the above realization, Chelsea notes that ascompared to E. coli,
Azotobacter will generate more __________ from the breakdown of oneglucose
molecule to two pyruvate molecules.
a. ATP
b. NADH
c. NADPH
d. CO2

4. Halloween is coming and Mike, Jenna, Ashley H. and Amanda P.decide to brew
some pumpkin Ale. They find a recipe online at The Brew Site.com.They add the
pumpkin, malt, wheat, vanilla, spices and hops. They then add thebrown sugar,
molasses and yeast. Finally, they are ready to ferment and theystarve the yeast of
O2 by placing an air seal on the top of the bottle. Once the O2 isdepleted from the
bottle
a. the fate of pyruvate changes.
b. the yeast utilize alcoholic fermentation in order to regenerateNAD+ and
allow glycolysis to continue running.
c. the yeast can generate only 2 ATP per molecule of glucose.
d. all of the above

5. In the pumpkin ale bottle (above), after O2 is depleted, doesthe TCA cycle
continue to turn? If not, why not? [*Mark all that apply.]
a. Yes
b. No, because the TCA cycle generates so much reducing power that,in the
absence of an externally derived terminal electron acceptor, couldnot be
regenerated.
c. No, because the ETC stops running.
d. No, because there is no reducing power generated in ananaerobic
environment.

6. Which one of the following events occurs during step 1 of theTCA cycle when
the acetyl group from acetyl-CoA is transferred ontooxaloacetate?
a. reducing power is generated.
b. CO2 is produced.
c. a carbon-carbon bond is formed.
d. ATP is generated via substrate-level phosphorylation.

7. In step 4 of the TCA cycle, a-ketoglutarate is converted tosuccinyl-CoA. All of
the following are true for both this step and the transition stepEXCEPT
a. both are catalyzed by dehydrogenases.
b. both involve the incorporation of a cosubstrate.
c. both generate reducing power and fully oxidized carbon.
d. both occur in the mitochondrial matrix of a eukaryoticcell.
e. both occur when fat is catabolized.

8. Succinate dehydrogenase [*Mark all that apply.]
a. requires a prosthetic group.
b. is complex II of the mitochondrial electron transportchain.
c. catalyzes the phosphorylation of GDP.
d. Is fondly called the âWonder Woman Enzymeâ

CHEM 153A Quiz: Week 8 SQ Part I Answers

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