1.) Respiration : For Obligate Anaerobes, what is used as the final electron acc
ID: 3478481 • Letter: 1
Question
1.) Respiration : For Obligate Anaerobes, what is used as the final electron acceptor? Why is oxygen toxic to these organisms, and what potential bi-products are produced that cause the oxygen to be toxic? What enzymes are produced by aerobic organisms to process these potential toxic bi-products?
2.) Fermentation: Discuss the similarities and differences between Lactic Acid and Alcohol Fermentation.
3.) Why are all organisms only capable of growing within a defined temperature range and what occurs above and below the range of viable growth temperatures? How does this affect enzymatic activity above and below the range of growth temperatures for any organism?
Explanation / Answer
1.In anaerobic respiration, final electron acceptor in the electron transport chain is an inorganic molecule other than oxygen like nitrate, sulfonate and carbonate. Oxygen is toxic to these organisms because these organisms do not possess catalase and superoxide dismutase, which convert the lethal superoxide formed due to oxygen.
2. muscle cells and some bacterial species produce NAD+ by transforming pyruvate into lactate and known as lactic acid fermentation. This process is catalyzed by lactate dehydrogenase. Both pyruvate and lactic acid contain 3 carbon atoms.
In alcoholic fermentation that occurs in yeast and several bacterial species, pyruvate is converted into ethanol in a two-step patheay. Pyruvate is decarboxylated to form acetaldehyde, which is then reduced by NADH to form ethanol. This process requires two enzymes, pyruvate decarboxylase and alcohol dehydrogenase.
Both the processes use pyruvate as substrate. Lactic acid Fermentation is a single step process involving single enzyme, whereas alcohol fermentation is a two step process, involving two enzymes. Decarboxylation occurs in alcoholic fermentation.
3. all organisms are capable of growing within a defined temperature range because the cell membranes of the cells in all animals compose specific concentration of saturated fatty acids and unsaturated fatty acids, which is essential for its intactness at that specic range of temperature. When the composition changes, the membrane fluidity changes and leads to disruption of membrane.
All the enzymes have optimal range of temperature and pH, only at which it is highly functional. i.e, it can bind to substrate and convert into product only at that temperature range.
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