Meiosis and Variation

What is the purpose of sexual reproduction?

To have the genetic makeup of offspring different from that of its parents.

What three factors are responsible for the genetic variation of all sexually reproducing organisms?

1. independent assortment
2. random fertilization
3. crossing over

What is independent assortment and when does it occur?

hhen genes that do not reside on the same chromosome may sot independent of one another; this happens during anaphase 1 of meiosis

What is crossing over and when does it occur?

when genetic information is exchanged between homologues, furthering the shuffling of genetic information; happens during prophase 1 of meiosis

With whom does the chromatid cross over with?

non-sister chromatids of homologous chromosomes

Which chromosomes do not have a homolog and thus do not usually cross over?

the Y chromosome