What is meiosis ?
Meiosis means production of gametes.Meiosis is a process that converts diploid nuclei, to haploid nuclei.
Meiosis has three main parts
-interphase
-meiosis 1
-meiosis 2
INTERPHASE
It is same with mitosis' interphase.Organelles and DNA replicates itself.Each chromosomes have two chromatids which have same genetic materials and they attached each other with centromeres.Cell's metaborical activite rate is high.
MEIOSIS 1
PROPHASE 1
It is the longest stage of meiosis.Chromatin fibers get small and thick.Homolog chromosomes that each have two sister chromatids comes together and produces a pair.This stage is called synapsis.Each chromosomes pair has four chromatids.This group is called tetrad.During synapsis homologous chromosomes' nonsister chromatids does piece change.This stage is called crossing over.Crossing over happens with nonsister chromatids does cross with one on the top of the other, and this place is called chiasma.Chiasmas , hold together homologous chtomosomes until Anaphase 1.Also in Prophase 1 centrioles separate from each other and goes to the poles of the cell and in the end of this stage chromosome tetrads captured by spindle microtubules are moved toward the center of the cell.
METAPHASE 1
Tetrads stands on the center of the cell.
ANAPHASE 1
Homolog chromosomes which were hold together in Prophase 1 are separating by the help of the spindle fibers' getting smaller.They go to opposite poles of the cell.Anaphase 1 is different with mitosis because in mitosis sister chromatids were separated is Anaphase stage.
TELOPHASE & CYTOKINESIS
Chromosomes that has gone to the poles come bigger and thinner again.Nuclear envelope and nucleus appears again.But some of the cells don't do that they just continue to meiosis 2.With separating of cytoplasm has 1 homologous chromosomes and haploid (n) two cells are produced.
MEIOSIS 2
At the beginning of the meiosis 2 DNA doesn't replicate itself.Because each chromosome still has two sister chromatids.
PROPHASE 2
Nuclear envelope breaks down.Spindle fiber occurs and it attaches chramatids' kinectochores.
METAPHASE 2
Chromosomes stands in the middle of the cell like they did in the mitosis.
ANAPHASE 2
Sister chromatids separate from each other and goes different poles of the cell like mitosis' Anaphase.
TELOPHASE 2 &CYTOKINESIS
Nuclear envelope is done again.Cytokinesis happens and each is haploid four cells are formed.
Meiosis has three main parts
-interphase
-meiosis 1
-meiosis 2
INTERPHASE
It is same with mitosis' interphase.Organelles and DNA replicates itself.Each chromosomes have two chromatids which have same genetic materials and they attached each other with centromeres.Cell's metaborical activite rate is high.
MEIOSIS 1
PROPHASE 1
It is the longest stage of meiosis.Chromatin fibers get small and thick.Homolog chromosomes that each have two sister chromatids comes together and produces a pair.This stage is called synapsis.Each chromosomes pair has four chromatids.This group is called tetrad.During synapsis homologous chromosomes' nonsister chromatids does piece change.This stage is called crossing over.Crossing over happens with nonsister chromatids does cross with one on the top of the other, and this place is called chiasma.Chiasmas , hold together homologous chtomosomes until Anaphase 1.Also in Prophase 1 centrioles separate from each other and goes to the poles of the cell and in the end of this stage chromosome tetrads captured by spindle microtubules are moved toward the center of the cell.
METAPHASE 1
Tetrads stands on the center of the cell.
ANAPHASE 1
Homolog chromosomes which were hold together in Prophase 1 are separating by the help of the spindle fibers' getting smaller.They go to opposite poles of the cell.Anaphase 1 is different with mitosis because in mitosis sister chromatids were separated is Anaphase stage.
TELOPHASE & CYTOKINESIS
Chromosomes that has gone to the poles come bigger and thinner again.Nuclear envelope and nucleus appears again.But some of the cells don't do that they just continue to meiosis 2.With separating of cytoplasm has 1 homologous chromosomes and haploid (n) two cells are produced.
MEIOSIS 2
At the beginning of the meiosis 2 DNA doesn't replicate itself.Because each chromosome still has two sister chromatids.
PROPHASE 2
Nuclear envelope breaks down.Spindle fiber occurs and it attaches chramatids' kinectochores.
METAPHASE 2
Chromosomes stands in the middle of the cell like they did in the mitosis.
ANAPHASE 2
Sister chromatids separate from each other and goes different poles of the cell like mitosis' Anaphase.
TELOPHASE 2 &CYTOKINESIS
Nuclear envelope is done again.Cytokinesis happens and each is haploid four cells are formed.