1. (4 pts) In C. elegans three markers : HYG-GFP-DPY are closely linked in this

Question

1. (4 pts) In C. elegans three markers : HYG-GFP-DPY are closely linked in this order. A C. elegans male hyg + + ("hyg" is a mutant allele allowing for antibiotic resistance and "+" - wild type allele is GFP and DPY deficient) was crossed to a hermaphrodite + gfp dpy (“+” is wild type for hyg meaning the organism dies when treated with the antibiotic; gfp and dpy mutant alleles have GFP and DPY present). Give an example of:

a) Draw gametes that were derived from a single meiocyte from a single offspring in the aforementioned cross that shows "gene conversion" of GFP without crossing-over (include genotypes of all gametes)

b) Draw gametes that were derived from a single meiocyte from a single offspring in the aforementioned cross that shows "gene conversion" of GFP associated with crossing-over (include genotypes of all gametes)

Explanation / Answer

The cross is: hyg + + X + gfp dpy

Result will be: hyg + + , + gfp dpy (parental types) – These will be obtained without crossing over.

The single meiocyte without crossing over will have the gametes: hyg + + , + gfp dpy, hyg + +, + gfp dpy

hyg + + is the gamete showing gene conversion of ‘gfp’ without crossing over (Answer to Part ‘a’)

The single meiocyte after crossing over will be known as Tetrad. It will have the following gametes:

hyg+dpy, +gfp+, hyg gfp dpy, +++

+++ is the gamete showing gene conversion of ‘gfp’ with crossing over. (Answer to Part ‘b’)

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