Meiosis Flashcards
What do gametes only have? What occurs during gamete fusion?
one copy of each chromosome, so, that when gamete fusion takes place, you get the right number of chromosomes again
How do you make gametes ?
cells divide by meiosis ( half the number of normal chromosomes ), this process involves 2 cell divisions . In humans, it only happens in the reproductive organs.
Steps of meiosis
1) Before the cell starts to divide, it duplicates its genetic information, forming two armed chromosomes - one arm of each chromosome exactly same to the other arm, after replication the chromosomes form themselves into pairs
2) In the first division in meiosis, the chromosomes line up in the centre of the cell
3) the pairs are pulled apart so each new cell has one copy of each chromosomes, some of fathers and mother chromosomes go in each new cell
4) In the second division, the chromosomes line up in the centre of the cells and the arms are pulled apart
5) You get 4 gametes, each with a single set of chromosomes in it, each gametes genetically different from other because chromosomes shuffled together during meiosis and gametes only get half of them at random
What happens after 2 gametes have fused during fertilisation?
the resulting new cells divide by mitosis to make a copy of itself
Mitosis repeats many times to produce lots of cells in an embryo
As the embryo develops, these cells then start to differentiate into different types of specialised cell that make up a whole organism
