Meiosis Flashcards
what is meiosis?
cell division which produces 4 daughter cells that are genetically different from each other
why is meiosis important?
- ensures there is a constant number of chromsomes in adults of species (otherwise number of chromosomes would double every generation)
what are three causes of genetic recombination?
- independent assortment/segregation
- crossing over
- random fertilization
what is independent segregation?
randomly line up at metaphase plate in different combination
what is the effect of chromsomes crossing over?
- when they overlap, they can swap alleles
what is random fertilization?
different chromosome combinations
what is the overall name for Meiosis 1?
reductional division - number of chromosomes reduces by half
what happens during interphase ?
- DNA replication
chromatids are copied to form 2 chromosomes
what happens during prophase 1?
homologous chromosomes pair during synapsis
- centrioles move to opposite poles/ nucleolus disappears/ membrane breaks down
- chromosomes become visible
crossing over may occur during late prophase
what happens during metaphase 1?
homologous pairs align at metaphase plate
what happens during anaphase 1?
full chromosomes pulled apart by spindle fibres
- chromosomes separate
what happens during telophase 1?
- spindle disappears
- cell divides by cytokinesis forming two daughter cells
what happens during prophase 2?
cells have one chromosome from each homologous pair
what happens during metaphase 2?
chromosomes align at metaphase plate
what happens during anaphase 2?
chromsomes ripped apart by spindle fibres
- individual chromatids pulled to opposite poles
