Meiosis Flashcards
What happens during sexual reproduction?
Two gamete cells combine to form a new individual
How many copies of each chromosome do the gametes have?
One
So when you combine the mother and fathers gametes you end up with the right number of chromosomes for a normal body cell
How many Chromosomes do the gametes have?
23
How do children have features from both parents?
The new individual will have a mixture of two gets of chromosomes
What type of reproduction using meiosis?
Sexual
This is why sexual reproduction produces variation
What is meiosis?
Meiosis produces cells which have half the number of normal chromosomes in
Where is the only place in humans that cells divide by meiosis?
In the reproductive organs (ovaries and testes)
What is the first step in meiosis?
Before the cell divides it duplicates its DNA
So one arm or each chromosome is an exact copy of the other arm
How many divisions are there in meiosis?
2
What happens in the first division?
The chromosome pairs line up in the centre of the cell
The pairs are pulled apart so each new cells only has one copy of each chromosome (some fathers and some mothers in each)
What happens in the second division?
The chromosomes like up in the centre of the two cells and the arms of the chromosome are pulled apart
What is produced from meiosis?
Four gametes each with only a single set of chromosomes in
The cells won’t be identical
What would happen after two gametes join at fertilisation?
The cell grows repeatedly by dividing by mitosis
