BIO Homework 4

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All answers must be in your own words. Answers copied directly from the textbook, PowerPoint, or an online source will not be given credit.

1.You set up two cultures with an equal amounts of Escherichia coli. You label one culture “A” and the other “B.” Each culture is given 100mL of tryptic soy nutrient broth. You then take culture A and incubate it in the absence of oxygen and take culture B and incubate it in the presence of oxygen for one week. If E. coli is able to use both aerobic and anaerobic metabolism, the how would we classify it? Is it an obligate aerobe, obligate anaerobe, or a facultative anaerobe? Based on that information, which flask, A or B, would have more cells at the end of the week? Fully explain your answer.

2.What is NAD (NAD+) and NADH? Describe them as if you were a chemist. Why is NAD needed by all cells no matter what type of metabolism they use?

3.If an obligate anaerobe was no longer able to use the process of fermentation (and is not capable of anaerobic respiration,) would it still be able to produce ATP via glycolysis? Why or why not?

4. An obligate aerobe growing in an oxygenated environment is suddenly moved to an environment without oxygen. Explain what would happen to its metabolic pathways. Start with the Electron Transport Chain and work your way backwards to glycolysis.

5. What does a cell use ATP for? Imagine that you give an obligate aerobe cell 1 molecule of glucose. How many net ATP can it make? Imagine that you give an obligate anaerobe cell 1 molecule of glucose. How many net ATP can it make?

6. Eukaryotic cells have mitochondria (membrane bound organelles with separated compartments)

that allow them to use the electron transport chain to create a proton gradient capable of powering the ATP synthase enzyme. We know that prokaryotes do not have membrane bound organelles. How then do they accomplish this task? Describe for full credit