Viewing a single comment thread. View all comments

NeedleworkerCapital8 OP t1_j8h85s7 wrote

Reply to comment by SignalDifficult5061 in Why does X-inactivation happen? by NeedleworkerCapital8

Thank you a lot once again, you explained it clearly for me and i hope i understood it right, but i have a question still if you can, shouldn't allele dominance solve the issue? As in, we have an allele of each gene encoded in each X chromosome, if each gene has a dominant allele that is expressed and a regressive one which is not, wouldn't that mean that the total expressed wouldn't surpass the genes of one X chromosome? Or is co-dominance going to create enough duplicates for it to be troublesome, i know allele dominance is way more complex than that but I'm wondering where I'm being wrong.

2

Luenkel t1_j8i1lzu wrote

Dominance has nothing to do with which genes are expressed. It's not about one allele "recognizing" and shutting off the other. Generally speaking for a gene on an autosomal chromosome, both alleles will be expressed. Dominance is a question of whether the effect of one allele can mask the effect of another. So for example let's say you had an allele that produces a protein which is toxic in some way and thereby causes a disease. Then even in a heterozygous organism the single copy of this toxic allele might be enough to produce the diseased phenotype and therefore that allele would be classified as dominant. The healthy version of the protein would still be present in cells but that doesn't matter. I recommend you read the "molecular mechanism" section on the wikipedia article on dominance for more examples and details.

6

NeedleworkerCapital8 OP t1_j8iswr0 wrote

I understand allele dominance clearer now, it makes more sense this way, Thanks a lot

3