Quote Originally Posted by Family Jewels View Post
.... Think of homologous chromosomes like the right and left side of a ladder, and morphs are hanging out at each corner where a rung meets the side of the ladder. You could have two albinos hanging out on the 10th rung, a normal and a lesser sitting on the 1st rung, plus two pastels on the 2nd rung. That ladder would represent an albino super pastel lesser, right? That's because all those morphs occur at different loci (or "rungs") and the morphs on one rung don't have any effect on any of the other rungs. They don't care about each other. However, special, mystic, and mojave, etc. will only hang out on the 4th rung. They can't occur anywhere else, and each side of the ladder can only come from one parent. ....
I agree with everything Family Jewels wrote except this ladder analogy. I've seen it in a number of herper web sites, but it is wrong. If we liken a DNA molecule to a ladder, then a gene is both sides of the ladder. The entire ladder comes from either one parent or the other.

There are two chromosomes in a pair of homologous chromosomes. Each chromosome contains a DNA "ladder". One chromosome in the pair comes from the mother, and the other chromosome comes from the father. One member of a gene pair is in the DNA in the mother's chromosome, and the other member of the gene pair is in the DNA in the father's chromosome. And by the way, ball pythons have 18 pairs of homologous chromosomes.

See http://ghr.nlm.nih.gov/handbook