B2 5.1-5.2 Mitosis and Meiosis
- Created by: Sophie
- Created on: 22-11-14 16:26
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- Cell Division
- Mitosis
- Replaces damaged cells
- Allows all living organisms to grow
- Allows organisms to replicate whole copies of themselves
- Supplies new cells quickly and correctly
- The cell that is going to divide must double its contents
- Replicates chromosomes and organelles like mitochondria and ribosomes
- The cell ends up with 46 pairs of chromosomes
- Divides into two new cells
- Daughter cells
- 23 pairs of chromosomes (two sets)
- Carry the same genetic information as the parent cells
- Daughter cells
- Divides into two new cells
- Can be used by some plants to reproduce asexually
- One division
- Results in two identical cells
- Meiosis
- Gametes are formed through this process
- Gametes contain 23 chromosomes (a single set)
- Takes place in the testes of a male
- Sperm
- Takes place in the ovaries of a female
- Ova
- Only involved in forming gametes
- Varied offspring
- Produces 4 different gametes
- Doubles up chromosomes
- Ensures there are enough -too many/too little the cell won't work properly (or even at all)
- 1st division - a cell with 46 pairs of chromosomes splits into two - two cells each with 23 pairs
- 2nd division - 2 cells both split, forming 4 daughter cells each with varying chromosomes
- Cells are varied because it's totally random which chromosomes go into which cell
- In fertilisation, the gamete fuses with a gamete of the opposite sex so that the new cell has 23 pairs of chromosomes
- This cell then divides by mitosis
- Gametes are formed through this process
- Mitosis
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