1. A geneticist discovers a new mutation in Drosophila melanogaster that causes flies to shake and...

1. A geneticist discovers a new mutation in Drosophila melanogaster that causes flies to shake and shake. The geneticist gives this mutation the name of spastic (sps) and concludes that it is due to the presence of an autosomal recessive gene. You want to determine if the spastic gene is linked to a recessive gene for vestigial wings (eg). To do this, it crosses a homozygous fly for the spastic mutation and for vestigial characteristics with a homozygous fly for the wild characteristics and then uses the females of the F1 generation results to carry out a test cross. From this crossing, the generator obtains the following individuals: vg ", sps * = 230; vg, sps = 224: vg, sps" = 97 and vg ", asp = 99.

A) With an X ', show if genes are distributed independently

b) If not specifically distributed, determine the distance in map units between these genes

Solutions

Expert Solution

These genes are not distributed independently.

As we can see the parental phenotype are more than recombinant phenotype

Parental phenotype

vg ", sps * = 230;

vg, sps = 224:

Recombinant phenotype

vg, sps" = 97 and

vg ", asp = 99.

How we have concluded the parental and recombinant phenotype is explained in attached image below

If parental phenotype = recombinant

Than genes are said to be unlinked or independently assorted.

If parental phenotype > recombinant

There is linkage present

Recombinant frequency , directly proportional to distance between genes.

Distance between gene

or R. .F. = total recombinant/ total progeny

= ( 97+ 99)/ ( 230+224+97+99)

= 196 /650= 0.30

To determine percentage 0.30× 100 = 30 map unit

These two genes spa and vg are linked and located 30 map unit away from each other.

gladiator answered 1 year ago

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