Cell Division - Meiosis Flashcards
What happens during sexual reproduction (gametes ad chromosomes) ?
1) 2 gametes (sex cells) combing to form a new individual
2) Gametes only have 1 copy of each chromosome. This is so they can combine 1 sex cell from the ‘mother’ and 1 sex cell from the ‘father’ and still end up with the right no. of chromosomes in body cells
How does sexual reproduction produce variation?
The new individual will have a mixture of 2 sets of chromosomes, so it will inherit features from both parents
Where is the only place where meiosis takes place?
Reproductive organs (ovaries and testes)
Define meiosis
Meiosis produces cells which have half the normal number of chromosomes
What is the acronym for meiosis?
Makes Eggs In Ovaries Sperm In Semen
Describe the process of meiosis (4)
1) The cell duplicates its DNA - 1 arm of each chromosome is an exact copy of the other
2) In the 1st division the chromosome pairs line up in the centre of the cell
3) The pairs are then pulled apart, so each new cell has only 1 copy of each chromosome. (Some of the father’s and some of the mother’s chromosomes go into each new cell)
4) In the 2nd division the chromosomes line up again in the centre. The arms of the chromosomes are pulled apart
What are the main features of meiosis?
1) You get 4 gametes each with only a single set of chromosomes in it
2) There are 2 divisions