gametes
cells that contain half the number of chromosomes of a somatic cell.
germline cell
cells that produce gametes
ovary
testes
gonads
organs (not organ systems) that produce gametes using germline cells (ovary and testes)
meiosis
produces 4 daughter cells
each with have half the number of chromosomes of the original parent cell
2 nuclear divisions
prophase 1
appearance of chromosomes, homologous chromosomes synapse, and are crossing over between non-sister chromatids of homologous chromosomes may occur
metaphase 1
homologous pairs of chromosomes line up independently at the spindle equator
anaphase 1
homologous chromosomes are seperate and move towards opposite poles
telophase 1
chromosomes disappear. Nuclear membranes reform and the cell divides into two; each daughter cell has half the number of chromosomes as a parent
prophase 2
chromosomes reappear in each cell. each chromosome exist as two sister chromatids joined at the centromere.
metaphase 2
each chromosome lines up at the spindle equator
anaphase 2
centromeres are split and sister chromatids move to opposite poles.
telophase 2
chromosomes disappear. nuclear membranes reform and the cell divides into two.
increasing genetic variation
to produce gametes that are genetically distinct from each other
things that increase genetic diversity are: crossing over, independent assortment
chiasma/ chiasmata
where the chromatids overlap
prophase 1
crossing over
when sections of the chromatids detach and rejoin. this results in genetic variation, exchanging of DNA which make the offspring genetically different to the parent.
prophase 1
Recombinants
the chromosomes that have crossed over.
prophase 1
independent assortment
the random orientation of homologous chromosomes along the metaphase plate during metaphase 1