IMAT 2021 Q30 [SRY gene]

Could anybody explain this question? From wich topic is it, so i can study it later?

The topic is about “Sex-Linked Genes” and “The Chromosomal Basis of Sex” in general.

SRY, an acronym for Sex-determining Region of Y, is a Y-linked gene normally found on males’ Y chromosome, responsible for development of testes in early embryonic life. Lack of this gene imposes the development of the gonads to ovaries instead, even in an XY embryo. Besides, a translocation of this gene to an X chromosome can result to male characteristics irrespective of the sex chromosomes. So, option 1 will be valid.

Option 2 is incorrect due to the last argument. When SRY is in the zygot, it will exert its effect on the embryo i.e. male characteristics. This can happen after a possible translocation or not, after an incorrect division (here: trisomy) or a normal division. The result will be the same irrespective of whatever. The gene just need to be functional and not e.g. partially translocated, inverted, deleted, mutated and so on.

The option 3 is also valid too due to the above principles.

Thank you very much!!

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