7. In fruit flies, the gene for wing shape has an unusual allele called curly (d

Question

7. In fruit flies, the gene for wing shape has an unusual allele called curly (designated cy). The normal (wild type) allele is designated 'cy. A fly homozygous for cy (cy cy) has normal, straight wings. The heterozygote (Cy cy) has wings which curl up on the ends (and, incidentally, can't really fly). The homozygote for the Cy allele (Cy Cy) never hatches out of the egg. In other words, this allele is lethal in the homozygous condition. If two curly winged flies are mated, and the female lays 100 eggs, predict the following, showing appropriate work: a. How many eggs will produce living offspring? b. How many straight winged flies do you expect among the living offspring? c. What percentage of the living offspring do you expect to be curly winged like the parents? In cattle, there is an allele called dwarf which, in the heterozygote, produces calves with legs which are shorter than normal. This, again, is a homozygous lethal (the homozygous dwarf calves spontaneously abort early or a stillborn). If a dwarf bull is mated to 400 dwarf cows, what phenotypic ratio to you expect among the living offspring? 8. II. Incomplete/Co-dominance Mr, and Mrs. Anderson both have tightly curled hair. (The hair form gene shows incomplete dominance. There are two alleles, curly and straight. The heterozygote has wavy hair.) The Andersons have a child with wavy hair. Mr. Anderson accuses Mrs. Anderson of being unfaithful to him. Is he necessarily justified? Why or why not? 1. Two wavy haired people (one male and one female) marry and have eight children. Of these eight, how many would you expect to be curly haired, how many wavy haired and how many straight haired, assuming that the family follows the expected statistically predicted pattern? Suppose you examine the actual children and discover that three of the eight have curly hair. What do you suppose went wrong 2, 3. Basic body colar for horses is influenced by several genes, on of which has several different alleles. Two of these alleles--the chestnut (dark brown) allele and a diluting (pale cream) allele (often incorrectly called 'albino)-display incomplete dominance. A horse heterozygous for these two alleles is a palomino (golden body color with flaxen mane and tail). Is it possible to produce a herd of pure-breeding

Explanation / Answer

1. Tightly curled hair (CC) represents? autosomal dominant genes so the possible progeny could be

CC x CCC

There is 0% chance of a child with wavy hair which would only occur if one gene was dominant and other was recessive .

Therefore Mrs Anderson cheated Mr Anderson.

2.Two wavy haired people get married.

The possible outcomes are :

According to statistics 2 out of 8 children must have curled hair.

There is nothing possibly wrong the statistics are always not precise there can be a slight difference.

3. Pure breeding is not possible : When crossed the ratio comesut to be

25%- cream

50% Palomino

25 % chest nut

Ratio - 1:2:1

This is a case of incomplete dominance involving different genes and thus different allies therefore Pure breeding is not at all possible

C C C CC CC C CC CC

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