You work with a variety of apples that are red. Over the years, you\'ve seen som

Question

You work with a variety of apples that are red. Over the years, you've seen some variants (mutants) show up among your plants, and decide to investigate this matter further. You come up with two true-breeding variants, one that gives yellow apples, and one that gives orange apples. Through a series of monohybrid crosses, you establish that both are caused by recessive alleles. And now you decide to see how those genes interact between them (if at all). But first things first - you decide to determine if the alleles complement. You suspect that they will, because each gives you a different phenotype... but geneticists have seen some really weird things, trust me. So you set up a cross between yellow-apple and orange-apple trees. If the alleles complement, then you expect 100% of the progeny to have red fruit. And yet... 50% of the progeny shows up with red fruit, and 50% of the progeny has yellow apples. In 200 words or fewer, entertain an explanation of what may have happened here (i.e. formulate a hypothesis). Make sure to defend your hypothesis with a clear explanation of why it would explained the observed results

Explanation / Answer

Let the symbol for orange be ‘o’ and that for yellow be ‘y’

The cross is ooYy (orange) X OOyy (yellow)

Result: “OoYy” (red- O and Y complement) and “Ooyy” (yellow- ‘Y’ is epistatic over ‘O’)

Explanation: Orange and yellow color is due to recessive alleles. So, when genotype is ‘oo’ then orange color is obtained, and when genotype is ‘yy’, then, yellow color is obtained. It seems that ‘y’ is epistatic over ‘O’. That is why, recessive gene ‘y’ shows its yellow color in presence of ‘O’. On the other hand, ‘o’ is epistatic over ‘Y’. So, color of ‘o’ (orange) is expressed in front of dominant gene ‘Y’.

When both dominant genes are there (OoYy), then complementation is observed; resulting in red color.

Hypothesis: Complementation is there in the two dominant alleles of the genes.

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