Meiosis Cell division – ‘ reduction division’ Production of sex cells – gametes Meiosis errors dr shabeel pn
Why do we need meiosis? <ul><li>Meiosis is necessary to halve the number of chromosomes going into the sex cells </li></ul...
 
Meiosis Parent cell – chromosome pair Chromosomes copied 1 st  division - pairs split 2 nd  division – produces 4 gamete c...
Meiosis – mouse testes  Parent cell 4 gametes 1 st   division 2 nd  division
Meiosis – division error Chromosome pair
Meiosis error - fertilisation Should the gamete with the chromosome pair be fertilised then the offspring will not be ‘nor...
21 trisomy – Downs Syndrome Can you see the extra 21 st  chromosome? Is this person male or female?
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Meiosis Opt

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Meiosis Opt

  1. 1. Meiosis Cell division – ‘ reduction division’ Production of sex cells – gametes Meiosis errors dr shabeel pn
  2. 2. Why do we need meiosis? <ul><li>Meiosis is necessary to halve the number of chromosomes going into the sex cells </li></ul><ul><li>Why halve the chromosomes in gametes? </li></ul><ul><li>At fertilisation the male and female sex cells will provide ½ of the chromosomes each – so the offspring has genes from both parents </li></ul>
  3. 4. Meiosis Parent cell – chromosome pair Chromosomes copied 1 st division - pairs split 2 nd division – produces 4 gamete cells with ½ the original no. of chromosomes
  4. 5. Meiosis – mouse testes Parent cell 4 gametes 1 st division 2 nd division
  5. 6. Meiosis – division error Chromosome pair
  6. 7. Meiosis error - fertilisation Should the gamete with the chromosome pair be fertilised then the offspring will not be ‘normal’. In humans this often occurs with the 21 st pair – producing a child with Downs Syndrome
  7. 8. 21 trisomy – Downs Syndrome Can you see the extra 21 st chromosome? Is this person male or female?

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