A New Bacteriophage of E $B D E \quad 376 \quad B d E \quad 21 \quad b D E \quad 99 \quad \text { bdE } \quad 5$

question 36

Essay

A new bacteriophage of E.coli was isolated from the steam tunnels of New York City.Six mutant strains (a,b,c,d,e,f)were derived from it,each having a different single point mutation for the genes A,B,C,D,E,and F.Strain BDE was mated with strain bde.The order of genes given below does not necessarily reflect the order of the genes on the chromosome.The following progeny were observed:
$B D E \quad 376 \quad B d E \quad 21 \quad b D E \quad 99 \quad \text { bdE } \quad 5$
$\text { RDe } \quad 4 \quad \text { Bde } \quad92\quad \text {bDe } \quad 20 \quad \text { hde } \quad382$
a)What are the genotypes of the double crossovers,showing gene order?
b)Give the percent recombination between each pair of genes.
c)Draw a map showing the positions of the B,D,and E genes,with map distances between genes,where appropriate.
d)
(1) Give the formula you would use to calculate the coefficient of coincidence.
(2) Calculate the coefficient of coincidence.

e)
(1) Give the formula you would use to calculate interference.
(2) Calculate interference and specify whether the value is positive or negative

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