glycolysis practice problems key

glycolysis practice problems key - glucose implies that...

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Glycolysis Practice Problems Reading Chapter 16 End of the chapter questions (pp. 473-474): 3, 4, 8, 9, 10, 15, and 20 Answers in the back of the book Then try these: 1. Glucose is the primary metabolic fuel of the brain. Brain hexokinase has a K M is 0.05 mM, while the circulating blood glucose concentration is 5 mM. What is the advantage of this low K M ? Hexokinase catalyzes the first step in glycolysis. The low K m of brain hexokinase assures that glucose will be metabolized rapidly. 2. Yeast strains with mutations in the gene encoding phosphofructokinase cannot grow on media where glucose is the sole carbon source, but can grow on media where glycerol is the sole carbon source. Use your knowledge of glycolysis to explain this observation? Phosphofructokinase-1 catalyzes the third reaction in the pathway, therefore without PFK, glucose cannot be metabolized. The fact that mutant yeast can use glycerol but not
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Unformatted text preview: glucose implies that glycerol enters glycolysis at a later step. (Glycerol, is in fact converted to DHAP, but you do not need to know that to answer the question). 3. Explain why glycolysis can occur under aerobic or anaerobic conditions. There is no step in glycolysis that uses O 2 as an electron acceptor. Glycolysis does, however, generate 2 molecules of NADH per molecule of glucose. In the absence of a functioning electron transport chain, NAD+ pools are regenerated during fermentation. 4. In the glycolytic pathway, be able to identify: Steps where the input of ATP is required Steps where ATP is synthesized by substrate-level phosphorylation Step where NAD+ is reduced to NADH How NADH is oxidized back to NAD+ in muscle, in some yeast, and under aerobic conditions Irreversible reactions (under normal cellular conditions) Regulated enzymes...
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This note was uploaded on 05/06/2010 for the course BIOC 460 taught by Professor Ziegler during the Spring '07 term at University of Arizona- Tucson.

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