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Key Concepts
Types of Chromosomes

Karyotypes of large mammalian organisms, such as humans, show two major types of chromosomes; autosomes and sex chromosomes.

    Key concepts:
  • Human somatic cells have a total of 46 separate, individual chromosomes.
  • Of these chromosomes, 44 of them form 22 pairs of homologues of different sizes, structures and banding patterns.
  • These 22 pairs of chromosomes carry most of the genes which code for the human body; they are called autosomal chromosomes, or autosomes.
  • Two chromosomes are different. Usually termed "X" and "Y", these are the chromosomes that are involved in determining the phenotype of sexual identity; maleness or femaleness.
  • Under standard circumstances an individual that is XY is phenotypically male, while an individual that is XX is phenotypically female.

Science@a Distance
© 2001, Professor John Blamire