(F) Propose two logical mechanisms by which the female chromosome W can override
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Question
(F) Propose two logical mechanisms by which the female chromosome W can override the outcome of the male Y* chromosome. Explain how your proposed mechanism works *Research has shown that the sry gene is still present on the Y chromosome in these species Here is some additional information (from karyotype G-band staining) that may assist your thinking: X" male XY female XX female XX female X*Y (a) No panel shown. (b) The different sex chromosomes (X, X* and Y) paired and resulting gender; black dots indicate centromere position. Note that these images were the first images taken of the X chromosome; subsequently, X* was referred to as WExplanation / Answer
Sex chromosomes is that pair of chromosomes that defines wether the person is a male or a female. This is a pair of chromosomes in the organisms genome and rest all are called as autosomes. In humans the two sex chromosomes are XX and XY. If an individual has XX pair it will be a female and XY pair of chromosomes are present in males.
In different species sex determination is different. eg in Drosophila it is the ratio of autosomes to sex chromosomes that defines wether the fly is a male or a female. While in birds and poultry animals the two chromosomes Z and W defines the animals to be male or femlae ZW is a female while ZZ is male.
In past few years, RNA seq analysis have revealed that presence of W chromosome defines a female specific selection. There is a convergent selection of genes prsent on W chromosome for female specific traits. Genes on W chromosome are more responsive for female fertility traits despite of similar genes present in rest of the genome.
So even if Sry gene which is specific for male gender is presnt in the organism talked about in the given question. The genes presnt on W chromosomre masks the Sry gene and makes the organism female.
The other possibilioty for any organism to be a female inspite of having Y chromosme is the loss of Sry gene from Y chromosome by some mutation. And fir a male with XX chromosome is possible only if Sry gene is translocated on one of the X chromosomes.
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