GCSE Biology (AQA)

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Meiosis

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Inheritance, Variation and Evolution Reproduction

Meiosis

4:53 Sexual and Asexual Reproduction
Spec 4.6.1.2
Previous Sexual Reproduction in Plants Next Asexual Reproduction
  • ES (gametes) are formed by a type of cell division called meiosis.
  • Mitosis produces two genetically identical cells, each with 23 pairs of chromosomes.
  • Meiosis occurs in reproductive organs (testes and ovaries), producing four unique gametes.
  • Gametes have half the chromosome number to enable recombination and form a unique new organism.
  • Meiosis involves DNA duplication and an increase in subcellular structures like mitochondria and ribosomes.
  • In meiosis, a cell divides twice, resulting in four gametes each with 23 single chromosomes.
  • Gametes (sperm and egg in mammals, pollen and egg in plants) are genetically different from each other.
  • Meiosis creates genetic variation, important for producing genetically unique individuals.
  • Mitosis involves one cell division producing two daughter cells, while meiosis involves two divisions producing four daughter cells.
  • Daughter cells from mitosis are diploid (46 chromosomes), whereas those from meiosis are haploid (23 chromosomes).
  • Mitosis results in genetically identical cells; meiosis results in genetically diverse cells.
  • Understanding the differences between mitosis and meiosis is crucial, though detailed stages of meiosis are not required for exams.

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