MEIOSIS CELL DIVISION‬‏

MEIOSIS CELL DIVISION‬‏


let’s begin in the nucleus where genetic
information is stored in chromosomes let’s begin in the nucleus where genetic
information is stored in chromosomes most of the person’s cells are diploid
with two sets of chromosomes one set is from your mother shown here in red and
the other set is from their father shown in blue each maternal chromosome has a
corresponding paternal chromosome these matched pairs are called homologous
chromosomes during interphase chromosomes are duplicated each
chromosome now consists of two identical copies called sister chromatids zooming
in we see that each sister chromatid is made up of DNA wound around histone
proteins each strand coils up into a tight helical fiber as meiosis begins a
spindle forms and duplicated centrosomes start to migrate toward opposite poles
of the cell back in the nucleus the chromosomes are condensing in meiosis
homologous chromosomes stick together in pairs the close association of
homologous chromosomes allows segments of non sister chromatids to trade places this recombination of maternal and
paternal genetic material is a key feature of meiosis after the spindle
forms and the nuclear envelope breaks down microtubules from opposite poles
attached to each chromosome of the homologous pair resulting in a
tug-of-war at metaphase one the chromosome pairs are positioned in the
middle of the cell the next stage begins when homologous
chromosomes separate from each other and move toward opposite poles each
chromosome still consists of two sister chromatids this cell began meiosis with 46
chromosomes but each daughter cell now has only 23 chromosomes in meiosis two
microtubules from opposite poles attach to the chromosomes which then moved to
the center of the cell next the sister chromatids separate becoming
full-fledged chromosomes that move to opposite poles nuclear envelopes reform
and each daughter cell divides into two cells we started with a single diploid
cell and now that meiosis is complete we have four haploid cells cells with a
single set of chromosomes these haploid cells mature into gametes you

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