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Meiosis Cheat Sheet (DRAFT) by

This is a draft cheat sheet. It is a work in progress and is not finished yet.


Meiosis is a type of cell division
Takes place in the reprod­uctive organs
Cells that divide are Diploid to start with
Cells formed from meiosis are Haploid
These cells have Half the chromosome number
Daughter Cells Geneti­cally Different

Before the Start of Meiosis

DNA unravels and Replicates two Chromo­somes called Chromatids
2 Sister Chromatids are joined in the center by the Centromere
Meiosis 1 - the chromo­somes arrange into Homologous Pairs
Homologous Pairs Seperate halving the Chromosome number
This is Meiosis 1

Meiosis II

Sister Chromatids are separated
The Centomere is divided
Chromatids are now chromo­somes
4 Haploid cells are produced

Homologous Chromo­somes

Maternal and Paternal Chromo­somes
Paired together
chromo­somes are same size and carry same genes
The Different versions of those genes called Alleles
These pairs of Chromo­somes are called Homologous Chromo­somes


Meiosis is used to produce Gametes
Sex Cells, Sperm or Egg cells
These Cells fuse in fertil­ization to form a Zygote
Needs Half as many Chromo­somes as normal Cell
Diploid cell --- Haploid Cell
How DNA is passed on to generation

Phases of Meiosis

Interphase 1
Prophase 1
Metaphase 1
Anaphase 1
Telophase 1
Prophase 2
Metaphase 2
Anaphase 2
Telophase 2

2 Main Events that lead to genetic variation

Crossing over chromatids
Indepe­ndent segreg­ation of chromo­somes

Crossing over Chromatids

In meiosis 1 homologous pair of chromo­somes pair up
Bits of Chromatids swap over
Chromatids swap alleles
Different sets of alleles increase genetic variation

Meiosis II Image

Indepe­ndent segreg­ation of Chromo­somes

Homologous pairs of chromo­somes, one from mother, one from father
Maternal and Paternal Chromo­somes
Homologous pairs are sepere­ated, its random which chromosome end up in each daughter cell
Potential for different combin­ations
Indepe­ndent Segreg­ation of Chromo­somes
Genetic Variation in offspring
223 Potential variation for human chromo­somes