Pyruvate and Energetics of
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Pyruvate and Energetics of

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Pyruvate and Energetics of




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Slide1

Pyruvate and Energetics of Glycolysis

C483 Spring 2013

Slide2

1. The

conversion of pyruvate to ethanol also causes the ________.

A) oxidation of NADH

B) production of ADP

C) consumption of O2

D) generation of an ion gradient across mitochondrial membranes

2. The

enzyme that catalyzes the conversion of pyruvate to lactate is ________.

A) lactate

reductase

B) pyruvate kinase

C)

lactoenolpyruvate

D) lactate dehydrogenase

Which fate of pyruvate is an anaerobic process?

Formation of alanine

Formation of oxaloacetate

Formation of acetyl CoA

Formation of lactate

Slide3

Seven of the ten reactions in the glycolytic pathway have free energy values close to zero. What does this tell us about those reactions?

A) They are near equilibrium reactions.

B) They are not control points for pathway regulation.

C) They are reversible reactions.

D) All of the above.

E) None of the above.

Which of the following is false concerning steps 1, 3, and 10 of glycolysis?

All are catalyzed by a kinase.

All involve ATP hydrolysis

All have a negative standard free energy

All have a negative free energy under cellular conditions

All are irreversible steps.

Slide4

Fate of Pyruvate

Gluconeogenesis

Amino acid

and nitrogenmetabolism

Aerobic Energy

Anaerobic inmicroorganisms

Anaerobic in

h

igher organisms

Slide5

The Problem of Anaerobic Metabolism

With oxygen, the NADH produced in glycolysis is re-oxidized back to NAD

+

NAD

+

/NADH is a co-substrate which means…

If there is no oxygen, glycolysis will stop because…

The solution to the problem is to…

Slide6

The solution in Yeast

Pyruvate is

decarboxylated

(

cofactor?) to acetaldehyde

Acetaldehyde transformed to ethanol

What type of reaction?

What cofactor?

NAD

+

is regenerated to be reused in GAPDH

Slide7

Balanced Anaerobic Equation

Glycolysis: +Ethanol:______________________________

Slide8

The Solution in Us

Lactate formationBalanced equationDo the same exercise as yeast

Slide9

Overall Energetics of Glycolysis

Standard Free energy change, and standard free energy change at 37o with ionsProblem?

Slide10

Actual Free energy

Irreversible reactions: Which type of enzymes?Near-equilibrium reactionsNotice: reactions 5 and 6 together

Slide11

Answers

A

D

D

D

B

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