Breeding. Crossingover

Roman

Geneticist
Staff member
#1
Well. We began to study how the unicorns transmit genetic information (spoiler: the process is almost the same as in humans). I gave a description of the general process, and today I will plunge you into one of the particulars. We will talk about one of the two genetic operations that exist in unicorns. Today — the crossingover. Unicorns have a crossingover between the chromosomes, and this has a major influence on the inheritance and spread of genetic diversity.

Immediately show how this happens:
Difference-Between-Recombination-and-Crossing-Over-fig-1.png

Aha. This picture clearly shows what a crossingover of the chromosomes is. Here the unicorn has two chromosomes (we also remember that it is diploid). When two unicorns want to give birth to a baby, each of them randomly takes one chromosome. Accordingly, the descendant also has two chromosomes. And then they have the crossingover. It's like a deep intertwining of the vital essence of unicorns. Unicorns are weaved together in their descendants.

And here's how it's done. Each chromosome of the offspring is «cut» into two parts in the same random place, and then the second part of the first chromosome becomes the second part of the second chromosome and vice versa. Just like in the picture. And you should understand that this does not affect the unicorn phenotype, because no matter on what chromosome is the dominant allele of the gene, it is manifested in the phenotype. The crossingover of chromosomes does not affect the expression of genes. But the crossingover affects the inheritance and spreading of genes in the population. When a descendant with a crossingover makes a new offspring, who is a grandson for the original couple, then in this grandson, one chromosome carries genetic information from both grandmothers and grandfathers. If there was no crossingover, the grandchildren would carry genetic information only from grandmothers or only from grandfathers, and genetic diversity would be very narrow. And so — no.