9) (4 points) You have a patient who is sterile (unable to produce gametes), has

Question

9) (4 points) You have a patient who is sterile (unable to produce gametes), has ovaries and a uterus. What sex is this individual? but 10 (5 points) Based on what we know from human syndromes, what roles do the X and chromosome play in humans? Which is/are required for life? Which for fertility? required 11) points) In Drosophila melanogaster, white eyes are caused by an allele (X that is X linked and recessive to an allele for normal eyes X). A female fly that is homozygous for normal eyes mates with a male fly that has white eyes. a. What are the genotypes of each of the parent flies? Female Male: b. what genotype and phenotype will the male and female F1 progeny have? Please use the symbols given to you in the problem. Females: Males: c. If the Fl progeny are intercrossed, what percentage of the total progeny do you expect to be males with white eyes?

Explanation / Answer

9) This individual should be female as there is presence of ovaries and uterus.

10) X chromosome is one of the two sex determining chromosome in many animal species the other is Y chromosome. Females have two X chromosome where as Males have an X and a Y chromosomes.

X chromosomes has almost 2000 genes that are involved in different functions whereas Y chromosomes 200 genes out of which SRY gene is involved in triggering male characteristics.

Hence X chromosome is involved in many vital functions of life and Y chromosome helps in determining fertility.

11) Allele for Normal eye is X+ and allele for white eye is Xw

11- a) Genotype of female fly that is homozygous for normal eye is X+X+

   Genotype of Male fly that has white eyes is XwY

11-b) When male and female parents are crossed to produce F1 Progeny

Female Genotype is X+Xw   Male Genotype is X+Y

Female Phenotype is Normal eye,Heterozygous Male Phenotype is Normal eye, Hemizygous

11-c) If F1 Progeny Intercrossed

F1 Progeny male (X+Y) crossed with F1 progeny female (X+Xw)

As here we can see only one male progeny is havin genotype XwY hence having White eyes out of total of four progenies hence percentage of white eyes male will be 1/4 x 100= 25%

Xw Y Male Female X+ X+Xw X+Y X+ X+Xw X+Y

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