meiosis Flashcards
what is meiosis know as?
reduction division
what happens in meiosis 1?
pairs of homologous chromosomes are separated into two cells
what is the difference between prophase in mitosis and prophase 1 in meiosis?
homologous chromosomes pair up in prophase 1 forming bivalents
what happens in prophase 1 due to the chromosomes being large?
chromatids entangle called crossing over
what is the difference between metaphase in mitosis and metaphase 1 in meiosis?
homologous pairs of chromosomes line up on the metaphase plate
what happens in metaphase 1 that results in genetic variation?
independent assortment of chromosomes
what is independent assortment?
maternal or paternal chromosomes can end up facing any pole as the orientation is random and independent of any other homologous pair
what is the difference between anaphase of mitosis and anaphase 1 of meiosis?
homologous chromosomes are pulled to the opposite poles and chromatids stay joined together
what happens to sections of DNA on sister chromatids that became entangled in crossing over in anaphase 1?
break off and rejoin which may result in exchange of DNA
what are chiasmata?
points at which the chromatids break off and rejoin during anaphase 1
what is recombinant chromatids?
when exchange of genes occurs in anaphase 1 between chromatids
why does genetic variation rise in anaphase 1?
the genes being exchanged may be different alleles of the same gene so the combination of alleles on the recombinant chromatids will be different from the allele combination on either the orignal chromatids
new combination of alleles so sister chromatids are no longer identical
how does metaphase 2 differ from metaphase 1?
individual chromosomes assemble on the metaphase plate
why is more genetic variation produced in metaphase 2?
independent assortment occurs again
