A generalized transducing phage first infects a bacterial donor of genotype his+, trp+, and rif+. After lysis of the bacterial donor, a bacterial recipient of genotype his-, trp-, and rif– is infected and incubated with the same transducing phage. The cultures from this second infection are split into three fractions and plated on three different media conditions to select for transduction of each marker individually. Then each of those plates is replica plated on media lacking histidine, lacking tryptophan or containing rifampicin. The colonies observed on these replica plates are used to infer the genotypes listed below
Fraction 1 |
|
Fraction 2 |
|
Fraction 3 |
|
his + trp+ rif+ |
19 |
trp+ his + rif+ |
10 |
rif+ trp+ his+ |
13 |
his + trp+ rif- |
13 |
trp+ his + rif- |
20 |
rif + trp+ his- |
7 |
his + trp- rif+ |
33 |
trp+ his – rif+ |
5 |
rif + trp- his+ |
25 |
his + trp- rif- |
35 |
trp+ his – rif- |
65 |
rif + trp- his- |
55 |
What media was used to select for transductions in the first plating of each of the experiments? [6 points]
Fraction 1: |
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Fraction 2: |
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Fraction 3: |
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What is the order of the bacterial genes? (circle)