meiosis Flashcards
what is the significance of meiosis
-produces haploid cells = fusion of gametes during fertilisation
-genetic variation by independent assortment and crossing over= increases survival chances
what happens during interphase
the cell copies the chromosomes and organelles
what happens in the fist round of division in meiosis
what happens in the second round
1st- homologous chromosomes are separated from each other
2nd= sister chromatids are separated from each other
what happens during prophase 1
-chromosomes condense and become visible
-homologous chromosomes link together forming chiasmata = crossing over
-nuclear membrane breaks down and centrioles move to poles
-spindle fibres start to assemble
what happens during metaphase 1
-pairs of homologous chromosomes line up on the equator of the spindle apparatus
what happens during anaphase 1
-spindle fibres shorten and homologous chromosomes move towards the opposite poles
-chiasmata breaks
what happens during telophase 1
-nuclear membrane forms around each group of chromosomes which uncoil back to their chromatic state
what happens during prophase 2
-chromatin condenses and chromosomes become visible as sister chromatids
-nuclear membrane breaks down and spindle fibres begin to develop
what happens during metaphase 2
-chromosomes line up singly on the equator of the spindle
what happens during anaphase 2
-centromeres split and chromatids separate to opposite poles
-spindle fibre shorten
what happens during telophase 2
-chromatids reach the poles and become surrounded by nuclear membranes
-cytokinesis follows
in meiosis when does crossing over happen
what is it
-prophase 1
-non-sister chromatids exchange genetic materials
in meiosis when does independent assortment happen
what is it
-metaphase 1 and 2
-when the chromosomes align on the equator randomly
