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#### aktorque

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Genes on the bacterial chromosome have the following linkages in conjugal transfer: x and y, 25% of the time; y and z, 50% of the time. If the gene order is x-y-z, approximately what percentage of the time will x and z be transferred together?

A. 1% of the time
B. 5% of the time
C. 13% of the time
D. 20% of the time
E. 40% of the time

• DoctorNo, ibukun and Mondoshawan

#### Mondoshawan

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C.

My guess is C. 13% of the time

Chance that a Y will come with a Z (.5) * chance that an X will come with that Y (.25)

.25 * .50 = .125 ≈ 13%

• aktorque

#### Hope2Pass

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Not sure

Im not sure how to answer this question
but i was thinking along the lines of

(0.25+0.50) - (0.25*0.50) which equals 62.5

this gives probability of not mutually exclusive events.
Not sure, im waiting for the answer and an explanation!

• Mondoshawan and aktorque

#### Mondoshawan

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Im not sure how to answer this question
but i was thinking along the lines of

(0.25+0.50) - (0.25*0.50) which equals 62.5

this gives probability of not mutually exclusive events.
Not sure, im waiting for the answer and an explanation!
:notsure:
Doesn't that give the probability of one of two events happening or both (genes transferred ∈ {x,y} ∪ {y,z} ∪ {x,y,z})?

The events for which the probabilities are given aren't mutually exclusive; however, they are also not separate, since x, y, and z are on the same chromosome. {x,y,z} is the only set that could include both x and z.

I was thinking of the probabilities as approximating synteny; that is to say, since y and z together is twice as probable as x and y, then y and z must be about half the distance apart:

------x------y---z----------

So the probability that the whole string would be transferred would approximate the probability of the x-z synteny, which would be the inclusive probability of both the x-y and y-z syntenies. Which, I think, is the product of the two. • Hope2Pass and aktorque

#### aktorque

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Discussion Starter · ·
My guess is C. 13% of the time

Chance that a Y will come with a Z (.5) * chance that an X will come with that Y (.25)

.25 * .50 = .125 ≈ 13%
Very good.

Correct Ans is C) 13%

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