Shown below is a schematic of a nucleus of a cell with the genotype DdEeFf, wher

Question

Shown below is a schematic of a nucleus of a cell with the genotype DdEeFf, where the D and E loci are on the large chromosome and the F locus is on the small chromosome. This cell was taken from an F1 organism that resulted from the cross of two true-breeding parents such that one of the true-breeding parents had the genotype DDeeFF and the other had the genotype ddEEff.

On a piece of paper, redraw this image for yourself and place the D, d, E, e, F and f alleles on the drawing.

Assume the nucleus you drew above enters meiosis. On a piece of paper, draw for yourself a new picture that represents the chromosomes as they could be when in metaphase of meiosis I. Include the D, d, E, e, F, and f alleles on the drawing and assume no recombination

You have the following parental cross:

If the F1 fly is crossed to a fly with a black body and vestigial wings (b vg) / (b vg) you see the following fly types in the population. Indicate if each is a parental or a non-parental type.

Black bodied fly with normal wings

Black bodied fly with vestigal wings

Brown bodied fly with normal wings

Brown bodied fly with vestigal wings

What would be the recombination frequency for two genes that are on separate chromosomes?

Between 0-50%

About 50%

Between 50-100%

The maximum recombination frequency seen between any two genes on the same chromosome is about 50%. In your own words, explain why this is the case.

You are studying genetics in a hypothetical fly and you find a fly that has purple eyes. Assume that the purple eye phenotype is due to a mutation at a single locus. Use the notation E and e, where the upper case letter is used for the allele associated with the dominant phenotype and the lower case letter for the allele associated with the recessive phenotype.

You cross a pure breeding male fly with purple eyes to a pure breeding female fly with normal eyes. All of the F1 offspring have normal eyes. From this experiment you determine that the purple eye phenotype is ______________ to the normal eye phenotype.

A. Dominant

B. Recessive

You cross an F1 male to an F1 female and see a 3:1 ratio of normal eyes to purple eyes in the 400 offspring. Given only this information, is it possible that the gene controlling eye color is on an autosome?

A. Yes

B. No

Given only this information, is it possible that the gene controlling eye color is on the X chromosome?

A. Yes

B. No

From your F1 by F1 cross, what evidence would support the hypothesis that the gene controlling eye color is on the X chromosome?

Explanation / Answer

According to cross in fly black body with vestigial wings with brown normal wings there are four progeny produced both parental and non parental type.

++/++ X bvg/ bvg

Gives b+, vg+ genotype

Means black body fly with normal wings = nonparental type

Black bodied fly with vestigal wings = parental type

Brown body fly with normal wings = parental

Brown body fly with vestigal wings = nonparental type.

Non larental types formed by recombination.

Two gene present on different chromosome has recombination frequency about 50%.

When two gene located on separate chromosome or far apart on same chromosome involve crossing over during every meiotic event. If the gene located close to each other has recombination frequency less than 50% because they are linked and not assort independently.

In the particular cross purple eye phenotype is recessive to normal eye.

Here, EE x ee

Gives Ee which indicate normal eye phenotype means purple eye phenotype is recessive.

Gene controlling the eye colour is an autosome. No it is not on X chromosome.

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