IN a generalized transduction system using P1 phage, the done is pur+ nad + pdx- and the recipient is pur- nad- pdx+. The donor allele pur+ is initially selected after transduction, and 50 pur+ transductants are then scored for the other alleles. The results follow
nad+ pdx+ 3
nad+ pdx- 10
nad- pdx+ 24
nad- pdx- 13
a) What is the cotransduction frequency for pur and nad?
b) What is the cotransduction frequency for pur and pdx?
c) Are nad and pdx on the same side or opposite sides of pur? Explain (Draw exchanges needed to produce the various transductant classes under either order to see which order best explains the results obtained)