Dominance - how exactly does it come about?

[ferrari599]

Hi

Could someone please explain the exact mechanism by which dominance of one allele over another occurs (or link to somewhere which does). I have read the wikipedia entry on it, however the mechanism by which it occurs is not explained in much depth at all.

Thanks in advance.

[alextemplet]

Basically, in most cases the dominant allele codes for something (let's say a protein, for example) and produces a fully-functioning product. The recessive allele has a slightly different code that either produces a faulty product or fails to produce a product at all. Thus, the dominant trait ends up being expressed while the recessive trait is not. For example, if a dominant allele T codes for a growth hormone, individuals with a that a dominant genotype (TT or Tt) will be taller than individuals with a recessive genotype (tt) since the recessive allele does not produce a functioning growth hormone. I'm simplifying a bit here but that's the general gist of it; hope it helps!

[stopherlogic]

I think the gene gets methylated, not sure though, you will have to check it. As to what tells the body that the recessive allele needs to be silenced its a mystery to me.

[MrMistery]

stopherlogic, you are getting gene regulation and alleles mixed up. I recommend you consult a genetics book on the role of cytosine methylation in gene expression