posted a question
When homologous chromosomes crossover, what occurs?

- Maternal alleles are "corrected" to be like paternal alleles and vice versa.
- Two sister chromatids exchange identical pieces of DNA.
- Each of the four DNA strands of a tetrad is broken and the pieces are mixed.
- Specific proteins break the two strands and re-join them with their homologs.
- Two chromatids get tangled, resulting in one re-sequencing its DNA.