10.5 Y-Linked Genes

In humans, the Y chromosome has been studied and is known to contain approximately 200 genes which provide instructions for making proteins. Because only males have the Y chromosome, the genes on this chromosome tend to be involved in male sex determination and development. Sex is determined by the SRY gene, which is the sex-determining region of the Y-chromosome.

Colorful image of a Y chromosome (dark blue), showing red pseudoautosomal regions at the ends, the green SRY gene and light blue centromere
Figure 10.5.1 Structure of the Y-Chromosome in Humans

Other genes on the Y chromosome are important for enabling men to father biological children (male fertility). Many genes are unique to the Y chromosome, but genes in areas known as pseudoautosomal regions are present on both sex chromosomes. As a result, men and women each have two functional copies of these genes. Many genes in the pseudoautosomal regions are essential for normal development.  Although the Y-chromosome is sex-determining in humans and some other species, not all genes that play a role in sex determination are Y-linked.

Y-linked traits, whilst few in number, do exist. For instance, the Y-linked trait of “webbed toes” causes a web-like connection between second and third toes, and “porcupine man” occurs when the skin thickens and gradually becomes darker, scaly, rough, and with bristle-like outgrowths. Since Y-linked inheritance involves the Y chromosome, Y-linked inheritance is passed on from father to son. Of course, Y-linked traits never occur in females, and occur in all male descendants of an affected male. The concepts of dominant and recessive do not apply to Y-linked traits, as only one allele (on the Y) is ever present in any one (male) individual (this, is of course, ignoring XYY syndrome, which is a rare chromosomal disorder that affects males. It is caused by the presence of an extra Y chromosome. Males normally have one X and one Y chromosome. However, individuals with this syndrome have one X and two Y chromosomes).

Take a look at the video, Sex determination by the Y chromosome, by Genetics/ UC Davis (2017) on YouTube, which looks at sex determination by the Y-chromosome.

Media Attribution

Reference

Genetics/ UC Davis (2017, December 31). Sex determination by the Y chromosome (video file). YouTube. https://www.youtube.com/watch?v=Fd31_gaRyME

License

Icon for the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License

Open Genetics by Natasha Ramroop Singh, Thompson Rivers University is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

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