In humans, SRY is located near a pseudoautosomal region (PAR) of the Y chromosom
ID: 162921 • Letter: I
Question
In humans, SRY is located near a pseudoautosomal region (PAR) of the Y chromosome, a region of homology between the X and Y chromosomes that allows them to synapse during meiosis in males and is a region of crossover between the chromosomes. The diagram below shows SRY in relation to the pseudoautosomal region.
About 1 in every 25,000 newborn infants is born with sex reversal; the infant is either an apparent male, but with two X chromosomes, or an apparent female, but with an X and a Y chromosome.
Explain the origin of sex reversal in human males and females involving the SRY gene:
Rare sex-reversed males carry an altered (a) chromosome that (b) a fragment of the (c) chromosome including the (d) . Thus, they develop male sex characteristics yet lack (e) chromosome. Rare sex-reversed females carry an altered (f) chromosome that (g) the SRY gene. Thus, they develop female sex characteristics even though they have (h) chromosome.
Please fill in the letters (a-h). With this word blank: (these words can be use more than once)
X
a Y
lacks
PAR
contains
SRY gene
an X
Y
SRY PARExplanation / Answer
Answer-
Rare sex reversed male carry an altered X chromosome that lacks a fragment of the y chromosome including the SRY gene. Thus they develop male sex characteristics yet lack a Y chromosome.
Rare sex reversed female carry an altered Y chromosome that contains a SRY gene. Thus they contain female sex characteristics even though they have a Y chromosome.
Explanation - Normal Human male contain XY chromosome in which Y Chromosome have a SRY gene which differential it from the X chromosome.SRY gene is a testis determining factor.A gene interaction triggered by Y chromosome to generate male characteristics which is managed by sox9 gene.once gene interaction triggered it continues the development of male characteristics even in the absence of Y chromosome.thus Y chromosome containing male which lack SRY gene still can produce male characteristics although it has an altered X chromosomeNormal female contain 2 X chromosome but in sex reversed female have an altered Y chromosome which contains SRY gene ( a fragment of Y chromosome ) but lack Sox 9 gene thus it develop female characters even in the presence of Y Chromosome.