Recombination of the Y Chromosome
This animation shows how recombination occurs between the X and Y chromosomes, then within the Y chromosome itself.
Most chromosomes recombine with their partners along their entire lengths, as illustrated in the first part of the animation. Modern X and Y chromosomes, however, recombine only at their tips. DNA sequences in the middle of the chromosomes do not recombine, so they are more likely to accumulate mutations and degenerate over the course of evolution.
Sequencing of the Y chromosome has revealed many palindromic sequences in its middle section. As shown in a later part of the animation, these palindromic sections may allow the Y chromosome to recombine with itself, to either repair mutated genes or to copy mutations between its arms. In this way, the Y chromosome is able to maintain its genome over evolutionary timescales.
Note that this animation has no audio. Depending on students’ background, it may be helpful to pause the animation at various points to discuss different structures or steps in the recombination processes.
allosome, crossing over, DNA, gene conversion, homologous recombination, mutation, palindrome, sex chromosome