Below is given a linkage map of a Neurospora chromosome. A_______________B______

Question

Below is given a linkage map of a Neurospora chromosome.

A_______________B_________________x

A-B: 10 M.U. B-x: 10 M.U. x: Centromere

Suppose you perform a cross AB x ab and analyze asci produced by a meiocyte. Which of the following statement IS NOT ture?

A) 10% of individual spores will indicate recombination between A and B

B) 20% of asci will have an MII segregation pattern for the B locus

C) 40% of asci will have an MII segregation pattern for the A locus

D) 20% of individual spores will indicate recombination between A and B

E) the number of cross-over between the loci A and B equals to the number of cross-overs between the centromere and the locus B.

Please explain each of Answers WHY they are TRUE or FALSE.

Explanation / Answer

Answer : D

Reason:

A) 10% of individual spores will indicate recombination between A and B and D) 20% of individual spores will indicate recombination between A and B

1 map unit = 1% recombination

10 map unit = 10 % recombination

The distance between A and B is 10 m.u so 10 % of individual spores will indicate recombination between A and B.

B) 20% of asci will have an MII segregation pattern for the B locus and C) 40% of asci will have an MII segregation pattern for the A locus

Total map units = 20 from A to X

Total map units x 2 = frequency for second division segregation pattern

20 x 2 = 40% for locus A which means 20% for loci B

E) the number of cross-over between the loci A and B equals to the number of cross-overs between the centromere and the locus B.

Because equal map distance between A and B & B and X

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