Question

(2. What is the distance between two loci that give a co-transduction frequency of 17% if you used a P1 bacteriophage that packages 2 minutes of DNA in its capsid? Note: 1 minute of DNA = 40,000 bp. A) 1.57 minutes B) 80,000 bp C) 1.18 minutes D) 35,700 bp E) 47,200 bp

genetics class

Answer 1

As per Chegg Q&A Guidelines, I am answering the first question i.e. Question 2.

When a bacteria is transduced with a P1 phage, a part of the DNA is taken in. Most often the DNA is not completely taken in. Hence when there are say two markers on the DNA, the probability of both markers being transduced into the cell decreases as the distance between the markers increases. This decrease is not linear and is captured efficiently by Wu formula.

The formula can be stated as:

C=1 - CIE

where, C is the cotransduction frequency, d is the distance between the markers in minutes and L is the length of the fragment transduced in minutes.

Thus, in our case, cotransduction frequency is 17% or C = 0.17 and the DNA packaged is 2 minutes. Therefore, L = 2 minutes.

-() – 1 = 21'0 :

=1-0.17 = 0.83

..d = 0.83 x 8 = 6.64

:id= 1.880 minutes 2 minutes

1:1 minute = 40000 bp

:: 2 minute = 2 x 40000 = 80000 bp

Hence the correct option is B.