MIC 102 MT2 questions with correct answers

Explain how auxotrophic mutants can be isolated and how they inform us about metabolic pathways CORRECT ANSWER - screen for mutations in prototrophs (an organism capable of synthesizing all its metabolites from inorganic material) that cause them to become auxotrophic for a certain metabolite - map the mutation to a particular enzyme, then match enzyme to metabolic pathway - accumulations of the intermediate made before the blocked pathway help us piece together the biosynthetic pathways predict the impact of a deleterious mutation in a metabolic pathway with regard to changes in the flux (flow) of that pathway and describe a change in nutrition that could compensate for the mutation CORRECT ANSWER if a certain enzyme in a pathway is deleted, then the accumulation of a reactant that the enzyme worked with would occur. In turn, other products further down the pathway wouldn't be produced. Adding these products that aren't made can compensate for the mutation. explain why some organisms can grow in very simple media (macrominerals, trace elements, buffer) while others require many growth factors. Correlate these traits with their lifestyles/habitat and genetic capacity CORRECT ANSWER - those that can grow in simple media have more of their genome for the biosynthetic pathways dedicated to creating the building blocks for the organism to survive - auxotrophs: a mutant organism that requires a particular additional nutrient that the normal strain doesn't - it depends on the genes that the organism has encoded for the synthesis of building blocks that it feels like it needs how does carbon fixation contribute to central metabolism? CORRECT ANSWER - it produces intermediates for central metabolism, such as fructose 6P (glycolysis), Glyceraldehyde 3P (glycolysis and PPP), ribose 5P (PPP), etc. - very expensive: 6CO2+18ATP+14NADPH———-f