Exam 15: Genetics of Bacteria and Bacteriophages

Performing a complementation test through cotransduction using mutant phage genomes created by X-ray mutagenesis (mutants a-e),as well as ones created by chemical mutagenesis using EMS (mutants 1-5),you get the following results: 1 2 3 4 5 a - + + - - b - + - - - c + + - - + d + - + + - e - - + + - Explain this data.

In a genetic cross between two bacteriophage T4 rII mutants,r⁺ recombinants are produced.The genetic changes in these two rII mutants must be

An Hfr strain of E.coli with the genotype a^+b+c+d+e+f+ is mated with an F^- auxotrophic strain with the genotype a^-b-c-d-e-f-.Conjugation is stopped at 10-minute intervals and the genotypes of the resulting conjugants are determined.The following results are obtained: After 10 minutes e⁺ After 20 minutes a^+e+ After 30 minutes a^+b+e+ After 40 minutes a^+b+d+e+ After 50 minutes a^+b+c+d+e+ After 60 minutes a^+b+c+d+e+f+ What is the correct order of genes on this bacterial chromosome?

In a series of cotransformation experiments,DNA fragments from x^+y+z+ donor bacteria were used to transform xyz recipient bacteria.The following transformation phenotypes were observed in the recipient cells: xy^{+z xyz+ x+y+z x+yz+} What does this imply about the gene order of x,y,and z?

In a bacterial species genes q,r,s,and t were mapped in minutes through interrupted mating experiments.The results placed q and s on the two outer ends,but r and t were not resolvable by minutes.You have discovered no phage that can infect this species.If you have a q r s t Hfr strain and a q^{- r- s- t-} F^- strain,how could you measure the distance between the genes in map units?