GRE子ject Test: Biochemistry, Cell, and Molecular Biology : Help with Other Metabolic Processes
Study concepts, example questions & explanations for GRE Subject Test: Biochemistry, Cell, and Molecular Biology
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Example Questions
Example Question #123 :Biochemistry
What is the primary purpose of fermentation?
Generate oxygen
Generate ethanol
Regenerate NAD+
Generate ATP
Regenerate NAD+
The primary purpose of fermentation is to regenerate the NAD+that was reduced to NADH during glycolysis. This is essential because the cell will need that NAD+to be able to go through glycolysis. In anaerobic environments, the Krebs cycle and electron transport chain cease to function, leaving glycolysis as the primary metabolic process for the cell to generate ATP. NAD+is an essential reactant for glycolysis, but is rapidly consumed when the electron transport chain is not running. Fermentation takes place in order to replenish this reactant and allow glycolysis to continue.
Ethanol and lactic acid can be products of fermentation, but are not the primary purpose for fermentation. No oxygen or ATP is generated during this process.
Example Question #124 :Biochemistry
In comparison to anaerobic metabolism, aerobic metabolism of glucose produces__________.
less carbon dioxide
fewer protons for pumping in mitochondria
more oxidized coenzymes
pyruvate
more ATP per glucose
more ATP per glucose
在有氧代谢,单一葡萄糖molecule produces significantly more ATP molecules than during anaerobic metabolism. The exact number depends on a number of things, including the organism, cell type, and NADH shuttle. Aerobic metabolism of glucose produces more reduced coenzymes, which drop off their electrons at the electron transport chain in the mitochondria. Electron transport provides energy to pump protons from the mitochondrial matrix into the intermembrane space. Both processes produce pyruvate.
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