Eye color in fruit flies is governed by the yellow gene, y+. Wild-type flies hav

Question

Eye color in fruit flies is governed by the yellow gene, y+. Wild-type flies have red eyes whereas yy flies have yellow eyes (y+ is completely dominant to y). Body color is governed by the gene cn+. Wild-type flies have brown bodies whereas cn cn flies have cinnamon colored bodies (cn+ is completely dominant to cn). You cross a y+y+ cn cn fly to a yy cn+ cn+ fly to generate F1 flies and then cross the F1s to generate F2 flies. Which of the follow types of F2 progeny are considered recombinant types? (Select 'Yes' or 'No' for each)

Yes No  Flies with cinnamon bodies and red eyes
Yes No  Flies with brown bodies and yellow eyes
Yes No  Flies with brown bodies and red eyes
Yes No  Flies with cinnamon bodies and yellow eyes

If in the cross described above cn+ and y+ are linked, which of the following do you expect to be true for the F2 progeny?

There should be more flies with brown bodies and yellow eyes than there are flies with cinnamon bodies and yellow eyes.
There should be fewer flies with brown bodies and yellow eyes than there are flies with cinnamon bodies and yellow eyes.
There should be the same number of flies with brown bodies and yellow eyes as there are flies with cinnamon bodies and yellow eyes.

Tries 0/99 Course Contents » » Assignment 7 7-8 (4 points each) Timer -l Notes à Evaluate b Feedback Pri by ye color in fruit flies is governed by the yellow gene, y+. Wild-type flies have red eyes whereas yy flies have yellow eyes (y+ is completely dominant to y). Body color is governed by the gene cn+. Wild-type flies have brown bodies whereas cn cn flies have cinnamon olored b olored bodies (cn+ is completely dominant to cn). You cross a y+y+ cn cn fly to a yy cn+cn fly to generate F1 flies and then cross the Fis to generate F2 flies. Which of the follow types of F2 progeny are considered recombinant types? (Select 'Yes' or 'No' for each) d bodies(en t is to on), You cro lies. Whichs Flies with cinnamon bodies and red eyes Flies with brown bodies and yellow eyes Flies with brown bodies and red eyes Flies with cinnamon bodies and yellow eyes Submit Answer Tries 0/99 f in the cross described above cn+ and y+ are linked, which of the following do you expect to be true for the F2 progeny? O There should be more flies with brown bodies and yellow eyes than there are flies with cinnamon bodies and yellow eyes O There should be fewer flies with brown bodies and yellow eyes than there are flies with cinnamon bodies and yellow eyes O There should be the same number of flies with brown bodies and yellow eyes as there are flies with cinnamon bodies and yellow eyes Submit Answer Tries 0/99 aies with of fies be feve same

Explanation / Answer

The phenotypes which are absent in parents, appears in the offspring is considered as recombinants.

First question:

Fly genotype

Phenotype

y+y+ cn cn

red eyes, cinnamon colored

yy cn+ cn+

yellow eyes, brown bodies

The recombinants

y+_ cn+ _

red eyes, brown bodies

Yy cn cn

yellow eyes, cinnamon colored

The answer for first question is

No - Flies with cinnamon bodies and red eyes

No - Flies with brown bodies and yellow eyes

YES - Flies with brown bodies and red eyes

YES - cinnamon bodies and yellow eyes

Second question:

If the genes are linked the parental categories in high in frequency where as the recombinants are low in frequency. So,

Parental categories below are high in frequency

y+y+ cn cn

red eyes, cinnamon colored

yy cn+ cn+

yellow eyes, brown bodies

recombinant categories below are high in frequency

y+_ cn+ _

red eyes, brown bodies

Yy cn cn

yellow eyes, cinnamon colored

The answer for the second question is

There should be more flies with brown bodies and yellow eyes than there are flies with cinnamon bodies and yellow eyes.

Fly genotype

Phenotype

y+y+ cn cn

red eyes, cinnamon colored

yy cn+ cn+

yellow eyes, brown bodies

The recombinants

y+_ cn+ _

red eyes, brown bodies

Yy cn cn

yellow eyes, cinnamon colored

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