Q Search in Document Document9 Layout References Mailings Review View , 12 . A^
ID: 207589 • Letter: Q
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Q Search in Document Document9 Layout References Mailings Review View , 12 . A^ A. A- ·-·-·, Pane cnance invoived B) You start by looking at the mutations that Yanofsky recovered. One of these mutations affected amino acid number 49 and changed it from Glutamic acid to Valine. If you took this mutant E.Coll line and exposed it to a mutagen that could potentially change bases, insert bases, or delete bases, what type of second mutation could you discover that would create a wild-type tryptophan synthetase gene and where would it be located? Name. Recitation Section C) Most of the mutations that Yanofsky recovered were missense mutations. However, Yanofsky also recovered a nonsense mutation that changed amino acid number 15 into a stop codon. This codon normally encodes Lysine. Does the recovery of this mutation support the hypothesis that this Lysine residue is critical in the tunction of the tryptophan synthetase protein? Why or why not? s English (US) + 10 can happen as a gene Up Hide Rehearse Record Side Show side Timings Slide ShowShow Media contreisExplanation / Answer
B) Yes, a reverse mutation can lead to a wild type phenotype from a mutant phenotype.Since the mutation which would be a point mutation occurs at position 49 that changes Glu to Val, a change in one nucleotide that is mutated can result in normal phenotype.
If Glu at position 49 is coded by codon :GAA, GAG
Then , mutation would result if any of the codon that codes for Glu is mutated to :GUA, GUG that codes for Valine.
If point mutation occurs again and U in both GUA and GUG are changed to A then it would result in Glu instead to Val and wild type phenotype can be restored.This would be located at the position of aminoacid 49.
C.Yes, the recovery of this mutation would support the hypothesis that lysine residue is critical in the functioning of the trypyophan synthetase protein because a non sense mutation that results in a stop codon results in formation of a truncated protein that loses its functionality.
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