GCSE Biology (AQA)

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Chromosomes

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Cell Biology Cell Division

Chromosomes

1:58 Chromosomes and Genes
Spec 4.1.2.1
Previous Population Size in Standard Form Next Haploid & Diploid cells
  • The nucleus of a eukaryotic cell contains chromosomes.
  • A diagram shows a eukaryotic cell with a nucleus depicted as a big blue blob.
  • Chromosomes within the nucleus are made of a single molecule of DNA.
  • Chromosomes are composed of coiled DNA strands.
  • Chromosomes can appear as X-shaped during cell division.
  • Before cell division, chromosomes duplicate and are visible as X-shaped structures.
  • Duplicated chromosomes are joined at the centromere.
  • The term "centromere" is not required for the exam.
  • Human body cells typically have 23 pairs of chromosomes, totaling 46.
  • Some individuals may have extra or missing chromosomes.
  • Chromosomes in body cells are normally found in pairs.
  • One chromosome of each pair is inherited from the biological mother (egg cell) and the other from the biological father (sperm cell).
  • Different eukaryotic animals and plants have varying numbers of chromosomes.

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