Meiosis and gametes

Biology, Genetics and evolution , Growth, development and reproduction, Human and Animal Biology, Age 14-16

A presentation to introduce this topic at KS4. It includes animations to show the cells at each stage of meiosis as well as explaining how gametes are formed (13 slides) There is also an activity sheet with questions about mitosis and meiosis which can be used to revise once both topics have been covered, and a diagram of cells during meiosis to test pupil understanding.


1Objectives:
What is meiosis?
What happens to the chromosomes during meiosis?Meiosis and gameteshttp://teachable.net/res.asp?r=11692Meiosis is a special type of cell division used to make sex cells (gametes)
Gametes need to have half the ordinary number of chromosomes
This means that when they fuse together during fertilisation the zygote has the same number of chromosomes as the parentsWhat is meiosis?What are the sex cells in humans called?Why do you think this is important?3The new cells are all different because the chromosomes get shuffled each egg or sperm only has half the parents chromosomes and which half is random
So if there are 23 pairs of chromosomes there are 223 possible combinations (in other words a huge number)
The important things to remember about meiosis are that it promotes variation within a species and maintains the correct chromosome numberWhy is meiosis important?4
4646Formation of gametes2323How many chromosomes here?51. The chromosomes get thickerWhat happens in meiosis?62. The chromosomes are copied and

MITOSIS
Name two places where mitosis occurs in humans
How do the daughter cells compare with the parent cell?
How many cells result from mitosis?
MEIOSIS
The other way in which cells are able to divide in the body is meiosis. It only happens when sex cells are being produced. Complete the following sentences into your science book using the words beneath:
In animals the sex cells are called _____ and _____. In plants the male cells are called _________ and the female cells are called _________. The purpose of meiosis is to produce a cell that has _______ the number of chromosomes that an ordinary body cell has. The full number of chromosomes is called the ________ number. Half this number is called haploid. Meiosis takes place in specialised cells within the sex organs the _____ in the male and the ______ in the female. The sex cells produced are known as gametes.
[eggs testes ovum diploid