BIOC13H3 Lecture Notes - Lecture 4: Pyruvate Dehydrogenase Complex, Pyruvate Dehydrogenase, Acetyl-Coa

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11 Jul 2020

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Lecture 4 topic 4a pyruvate dehydrogenase complex (june 8. 5: technical definition => the pyruvate dehydrogenase complex is a complex of three enzymes that converts pyruvate into acetyl-coa by a process called pyruvate decarboxylation. In the mitochondrion, pyruvate is oxidized to an acetyl group, which is carried to the citric acid cycle by coa. Porin/vdac (outer membrane transporter: voltage-dependent anion channel (vdac, major channel through which metabolites cross the outer mitochondrial membrane (omm, nomenclature is a bit misleading, since it"s not only negative molecules that pass through. Vdac channels, but really any small metabolites and proteins can pass through. If we close vdac, nothing can come into the mitochondrion (but this is fine because the proton gradient does fine as the source of energy, no cytosolic metabolites needed. Inner mitochondrial membrane (imm) transporters: things are a lot more complicated here (recall that the omm only had vdac as its transporter)

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

BIOC13H3 Lecture Notes - Lecture 4: Pyruvate Dehydrogenase Complex, Pyruvate Dehydrogenase, Acetyl-Coa

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