Explain why transduction cannot result from virulent phages. Two bacterial strai

Question

Explain why transduction cannot result from virulent phages. Two bacterial strains are auxotrophic for two different pairs of genes. Strain A is phe^+, trp^+ met-, his- and Strain B is phe^- trp^-, met^+ his^+ the two strains are cultured in a U-tube where the two sides are separated by a filter. the medium and anything dissolved in it can pass between through the filter, but intact cells are too large to pass. the culture medium on both sides also contains an enzyme that destroys any external DNA. After 24 hours, all of the cells on the side with Strain A are still auxotrophic, but some of the cells on the side with Strain B are now prototroph (phe^+, trp^+, met^+, his^+). What form of recombination is ruled out by the fact that intact cells cannot pass through the filter? What form of recombination is ruled out by the presence of the enzyme that would destroy external DNA? What form of recombination must be responsible for the conversion of some Strain B cells to prototroph?

Explanation / Answer

a)The recombination that is ruled out by the fact that the intact cells cannot pass through the filter is the combination of phe+ and met+.They create a blockage to preventintact cells to pass through.

b)The recombination that is ruled out by the presence of the enzyme that would destroy external DNA is due combination of trp+ and his+ as they rule out the fact of destroying the DNA.

c)All four are needed ->phe+,met+,trp+,met+ for the conversion.

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