Comment on If we get two sets of chromosomes, how does our body decide which genes to use?
AmidFuror@fedia.io 4 weeks agoBest explanation so far. Nice work.
A couple of side points. OP's X chromosome is definitely expressed. It has many genes that are essential to both men and women. It's genes are not exclusively relating to sex differences. In fact, far from it.
Sex determination in humans is due (mostly) to a few genes on the Y chromosome. These both determine which sex organs will develop and also are critical for male fertility.
One of the major consequences of having a Y chromosome that doesn't recombine with it's partner X chromosome is that the Y chromosome has a tendency to lose genes and shrink over evolutionary times. This is prevented on chrX because it can recombine in females. It happens on chrY because there is little mechanistically to prevent it, and mutations resulting in loss are more common than those resulting in gain.
Ranvier@sopuli.xyz 4 weeks ago
Oh yes absolutely op’s x chromosome is expressed. I just meant unlike all the other chromosomes where in general both gene copies on both chromosomes are expressed, in xx individuals usually one of the x chromomes is inactivated and only one of them is being expressed at a time. The x chromosome has many essential genes. This is why we have x linked genetic diseases as well. Often xx individuals are just carriers or more mildly affected since they have two x chromosomes, and xy individuals are more severely affected since they have no backup copies of that gene.