Question

SRY gene on Y chromosome is present in

• A. heterochromatin region
• B. euchromatin region
• C. PAR region
• D. q-arm

Answer 1

The correct option is B euchromatin region

The development of functional testes in human males is induced by the activity of the testes determining factor (TDF). This is encoded by the sex-determining region (SRY gene) located on the short arm (p-arm) of the Y chromosome in the euchromatin region.

Euchromatin is that part of chromatin that is lightly stained and transcriptionally quite active whereas heterochromatin is that part of the chromatin that is darkly stained and generally transcriptionally inactive.

PAR (pseudoautosomal region) are regions of homology between X and Y chromosomes. These regions help in pairing of X and Y chromosomes during meiosis. As PAR is located on both the ends of the chromosomes, it ensures pairing, end to end rather than along the whole length.