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Anonymous
06-05-2004, 01:24 PM
Problem 1: Glucose conversion
Glycolysis leads to the production of ____________ and two molecules of ATP. In the absence of oxygen, fermentation leads to the production of ______________. Glycolysis plus the citric acid cycle can convert the carbons of glucose to _________ , storing the energy as ATP, _____________ and ___________.

A. lactic acid, pyruvate, CO2, NADH, FADH2

B. pyruvate, lactic acid, CO2, NADH, FADH2

C. CO2, NADH, FADH2, lactic acid, pyruvate

D. O2, lactic acid, pyruvate, FADH2

E. glucose, lactic acid, CO2, NADH, FADH2







Products of glycolysis
In glycolysis, glucose with six carbons is converted into two molecules of pyruvate, each with three carbons. In the summary of glycolysis below, glucose converts to two molecules of pyruvate,yielding 2 ATP and 2 NADH.

http://www.biology.arizona.edu/biochemistry/problem_sets/metabolism/graphics/glycolysis_summary.gif


Products of fermentation
In fermentation, pyruvate is decarboxylated to acetaldehyde, and acetaldehyde is reduced by NAD+ producing lactic acid. Fermentation occurs in the absence of oxygen, and is designed to regenerate NAD+ to allow glycolysis to continue. Note that you can't use NADH for energy unless oxygen is present.

http://www.biology.arizona.edu/biochemistry/problem_sets/metabolism/graphics/fermentation_summary.gif


Products of glycolysis + the citric acid cycle
Glycolysis produces two molecules of pyruvate for each molecule of glucose. In in the presence of oxygen (aerobic), the pyruvate enters the mitochondria and is metabolized to CO2 and H2O in the citric acid cycle. A combination of glycolysis and the citric acid cycle oxidizes glucose to CO2 producing ATP and the reduced electron carriers NADH and FADH2. The reaction below summarizes the actions of glycolysis and the citric acid cycle.

http://www.biology.arizona.edu/biochemistry/problem_sets/metabolism/graphics/g+cac_summary.gif









ans:
B. pyruvate, lactic acid, CO2, NADH, FADH2

In glycolysis, glucose with six carbons is converted into two molecules of pyruvate, each with three carbons.

In fermentation, pyruvate is reduced by NAD+ producing lactic acid.

In the citric acid cycle, the carbons of glucose are converted to CO2 and the H atoms used to reduce NAD+ and FAD forming NADH and FADH2.