Meiosis, the splitting of cells that result in genetic variation and are exclusively for our sex cells.

• Sperm cells for males and ovum for females; these are the sex cells

Haploid Gametes

All somatic (body) cells in multicellular organisms are genetically identical due to mitosis

• All descended from a zygote

  Zygote forms when two haploid/gametes fuse; gametes are genetically different because they are formed from mitosis

Haploid: 1 copy of each chromosome (chromosomes 1-23), and diploid means that there are 2 copies of each chromosome

During cell division, only 1 chromosome from each homologous (same) pair is copied; results in only 23 cells.

Meiosis

Gametes are from cell division called meiosis

• This produces 4 daughter cells and results iin diversity and variation (all daughter cells rae haploids)
• Quite different from mitosis, in that there is crossing over and independent assortment
• Crossing over: when the chromosomes line up in the middle, they swap over a bit of genetic information, which cause variation
• Independent Assortment: In meiosis I, one chromosome from each pair goes to one of the cells while the other goes to another; this is completely random

Meiosis I

• Homologous pairs of chromosomes align in the middle of the parent cell and are separated
• Cell divides so each new daughter cells only contain one chromosome from each pair; 23 in total
• Introduces genetic diversity by randomly dividing a cell’s genes into 2; results in 2 haploid cells

Meiosis II

• Chromosomes align and its chromatids are moved to opposite ends
• Splits each chromosome into 2 chromatids and places 1 in each cell
• Results in 4 unique haploid genes

IPMAT for Mieiosis (there are 2 phases of this)

Prophase I

• DNA turns to chromosomes after each one duplicates (the two separate parts of the chromosome are called sister chromatids)

Metaphase I

• Chromosomes align at centre
• Crossing over and independent assortment here

Anaphase I

• Separate with sister chromatids remain together (the chromosome pair splits up; with one chromosome going one way and the other (they don’t break/actually split this time))

Telophase I

• Two daughter cells formed with each only containing one chromosome from the pair

Prophase II

• DNA condenses into chromosomes

Metaphase II

• Chromosomes line up (again)

Anaphase II

• Divide and sister chromatids move to each pole; this time the chromosomes actually break and divide into 2
• Like in mitosis

Telophae II

• Cell splits into 2 daughter cells (this happens to both of the cells) so 4 haploid cells in total are produced

BASICALLY THE SAME AS IPMAT BUT WITH CROSSING OVER AND INDEPENDENT ASSORTMENT