- L23 Which Of The Following Statements Is Not True About A Chromosome Duplication A Mutations Created By Duplications 1 (64.13 KiB) Viewed 20 times
L23. Which of the following statements is NOT TRUE about a chromosome duplication? A. Mutations created by duplications may be able to revert back to wild-type. B. One function of duplications is to supply a high copy number of genes encoding abundant proteins or RNA molecules. C. Duplications have played an important role in evolution by allowing the creation of multi-gene families. D. The number of duplicated sequences may expand or contract by unequal crossing over during meiosis. E. In duplication heterozygotes, crossing over is suppressed within the duplicated sequences. Q. PROKARYOTIC GENETICS Q18. In E. coli, the ley gene is needed to make leucine and leuß mutants are auxotrophic for leucine. Part of the wild- type leuB open reading frame has the sequence: 5...AGATTCGGATCT...3¹. At the same position, the Pleuß mutant strain has the sequence: S...AGATTCGAATCT...3. Three different F' strains, F' leuB-1 through F' leuB-3, each carrying a different mutant leuß allele on the F factor, were independently crossed to the FleuB strain by conjugation. After conjugation was complete the cells were plated onto medium lacking leucine to select for leuß recombinants. The cross using which F' plasmid produced (auß recombinants? A. F'leuB-1: 5...AGATTCGATCT...3' B. F'leuB-2 5...AGATACGGATCT...3¹ C. F'leuB-3: 5...AGATTCGAATCT...3' F27. An F E. coli strain has the lac operon genotype lac ro* pt zty. Which of the following lac operons, if introduced into the F strain on an F plasmid, would result in a strain that is inducible for galactosidase (lacZ) but never produces permease (lacX)? A) Flac I opt zyt Flac opzY I B) FlacroCp+z+y+ D) Flacopt z Y