Meiosis Flashcards
(14 cards)
What are gametes produced by ?
Meiosis
What happens when gamete fusion takes place ?
You get the right amount of chromosomes again (two copies of each)
Why do cells divide by meiosis ?
To make gametes which only have half the original number of chromosomes.
Where does meiosis take place in humans ?
In the reproductive organs (the ovaries in females and testes in males)
Before the cell starts to divide, it duplicates it genetic information. What does this form ?
Two armed chromosomes - one arm of each chromosome is an exact cope of the other arm
What do the cells do after replication in meiosis ?
The chromosomes arrange themselves into pairs
What is the first step in the first division in meiosis ?
The chromosomes pairs line up
in the centre of the cell
What happens after the chromosome pairs line up in the centre of the cell in the first division ?
The pairs are pulled apiary so each new cell only has one copy of each. Some of the father’s chromosomes and some of the mother’s chromosomes go into each new cell
What happens in the second division of meiosis ?
The chromosomes line up again in the centre of the cell. The arms of the chromosomes are pulled apart
What do you get at the end of meiosis ?
You get four gametes, each with only a single sent of chromosome in it .
How are each of the gametes genetically different from the other ?
Because the chromosome all get shuffled up during meiosis and each gamete only gets half of them , at random
What happened after two gametes have fused during fertilisation ?
the resulting new cell divides by mitosis to make a copy of itself
Why does mitosis repeat many times ?
To provide most of new cells in an embryo
What happens to these cells as an embryo develops ?
These cells then start to differentiate into the different types of specialised cell that make up a whole organism
