Meiosis

Meiosis- It is a reduction division. This means that the daughter cells have half of the original number of chromosomes. They are haploid.

Each division has four stages:
- Prophase
- Metaphase
- Anaphase
- Telephase
Before meiois 1, interphase takes place. This is when the DNA replicates. Each chromosome consists of two identical chromatids, joined at the centromere.
The cell will have four instead of two original copies of each chromosme.
Each chromosome is a chromatid.
A pair is called a sister chromatid.
Sister chromatids are joined together in the middle by a centromere.

Meiosis 1

Prophase

The chromatins condenses and supercoils.
Supercoiling makes the chromosomes shorter and thicker.
The chromosomes come together as homologous pairs to form a bivalent.
A bivalent is a pair of homologous chromosomes.
Each member of the pair have the same gene at the same loci. They each have the one maternal and one paternal chromosome.
Non sister chromatids wrap around each other and form chiasmata.
The undergo a process called crossing over. This is when the chiasmata may swap section s of chromatid with one another.
The nucleolous disappears and the nuclear envelope breaks down.
A spindle is formed. It is made of protein microtubles.

Metaphase

The bivalent line across the equator of the cell and they attach to spindle fibres at the centromere.
Each member of the homologous pairing face opposite poles.

Anaphase

Telephase

There is two nuclear envelope that forms around the chromosomes at each end of the poles.
In animals, the cytoplasm divides by cytokenesis and two haploid daughter cells are formed.
In plants, the cell goes straight from anaphase 1 to meiosis 2.

Meiosis 2

This is the same as meiosis one, however, it occurs with half the number of chromosomes.
In anaphase 2, the sister chromatids are seperated. Each new daughter cell…

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