Meiosis

  1. Interphase

2.Meiosis 1

3.Meiosis 2

S phase

G2

G1

cell gets larger

organelles being duplicated

Proteins and enzymes are made

DNA copies itself

makes sister chromatids

centrioles are duplicated

cell grows even more

makes more protiens and enzymes

centrioles start organizing microtubules

Metaphase 1

Anaphase 1

Prometaphase 1

Telophase 1

Prophase 1

Cytokinesis 1

Metaphase 2

Prometaphase 2

Anaphase 2

Telophase 2

Prophase 2

Cytokinesis 2

chiasmata form between the sister chromatids within the tetrad

crossing over happens at chiasmata

chromosome pair bond along the length witch forms tetrads (Tetris) (length bc its easier to switch sister chromatids)

chromosome condenses

DNA chromatin condenses into chromosomes

hardest step first

nucleus dissolves

centrioles start making microtubules into spindles and attaching them to homologous pairs at the kinetichore

with the help of centromeres and spindle microtubules, homologous pairs line up at the metaphase plate

cell membrane dissolves

spindle microtubules shorten and separate homologous pairs

centrioles with the sister chromatids still attached to them are pulled apart to opposite ends of the cell

maternal and paternal homologous pairs are separated from the microtubules

spindle microtubules separate the two new haploid cells

each cell contains 3 chromosomes from each homologous pair

nuclei form around separated chromosomes

chromosomes uncondensed

cell membrane forms

chromosomes arrive at opposite sides of the pole

in some organisms, nuclear membrane reforms and the chromosome condenses but in others, this step is skipped

occurs at the same time as telophase 1

two haploid cells are formed

the two new daughter cells pinch off and separate from each other at the cleavage furrow

centrosome starts making microtubules into spindles and attached them to the sister chromatids at the kinetochore

nuclear envelope breaks down if needed

centromeres move apart

starting cells are haploid made in meiosis 1

spindle form and spindle microtubules begin to catch chromosomes

DNA condenses to chromsomes

the nucleus dissolves

chromosomes line up individually

spindle microtubules shorten and separated sister chromatids

individual chromosomes are pulled to opposite ends of the cell

nuclei form around separated chromosomes

each cell is now an individual unique gamete

chromosomes condense
and cell membrane dissolves

spindle microtubules begin separating the 4 new haploid cells

splits the chromosome sets into new cells

final product of meiosis

four haploid cells

in humans, product is sperm or egg cells

the four new daughter gametes pinch off and separate from each other at the cleavage furrow

with the help of the centromeres and spindle microtubules sister chromatids line up at the metaphase

cell membrane dissolves