Meiosis

HideShow resource information
  • Created by: joshd
  • Created on: 13-03-14 13:03
What are gametes and what are they called for females and males? What do gametes do during sexual reproduction?
Gametes are 'sex cells'. They're called ova (single, ovum) in females and sperm in males. During sexual reproduction, two gametes combine to form a new cell whcih will grow to become a new organism.
1 of 11
Gametes are haploid. What does that mean and why is it done? Explain about zygotes.
They only have one copy of each chromosome. This is so that when two gametes combine at fertilisation, the resulting cell (zygote) has the right number of chromosomes. Zygotes are diploid - they have two copies of each chromosomes.
2 of 11
What do human body cells and gametes have, and what does it lead to?
Human body cells have 46 chromosomes. The gametes have 23 chromosomes each, so that when egg and sperm combine, you get 46 chromosomes again.
3 of 11
When do cells divide by meiosis?
When cells want to make new cells which only have half the original number of chromosones.
4 of 11
Where do meiosis only happen?
In the reproductive organs (e.g ovaries and testes).
5 of 11
What is the definition of meiosis?
Meiosis is when a cell divides to produce four haploid nuclei whoe chromosones are NOT identical.
6 of 11
Explain what happens first with Division 1 of Meiosis.
Like mitosis, before the cell starts to divide, it duplicates its DNA - one arm of each chromosome is an exact copy of the other arm.
7 of 11
What happens secondly with Division 1 of Meiosis?
The chromosome pairs line up in the centre of the cell. `
8 of 11
What happens thirdly with Division 1 of Meiosis?
The chromosome pairs are then pulled apart, so each new cell only has one copy of each chromosome. Some of the father's chromosomes (shown in blue) and some of the mother's chromosomes (shown in red) go into each new cell.
9 of 11
What happens fourthly with Division 1 of Meiosis?
Each new cell will have a mixture of the mother's and father's chromosomes. Mixing up the alleles in this way creates variation in the offspring. This is a huge advantage of sexual reproduction over asexual reproduction.
10 of 11
What happens firstly in Division 2 of Meiosis/ fifthly in Meiosis as a whole?
The chromosomes line up again in the centre of the cell. The arms of the chromosomes are pulled apart.
11 of 11

Other cards in this set

Card 2

Front

Gametes are haploid. What does that mean and why is it done? Explain about zygotes.

Back

They only have one copy of each chromosome. This is so that when two gametes combine at fertilisation, the resulting cell (zygote) has the right number of chromosomes. Zygotes are diploid - they have two copies of each chromosomes.

Card 3

Front

What do human body cells and gametes have, and what does it lead to?

Back

Preview of the front of card 3

Card 4

Front

When do cells divide by meiosis?

Back

Preview of the front of card 4

Card 5

Front

Where do meiosis only happen?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all Meiosis resources »