Inheritance, Genes & Chromosomes

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  • Created by: Lucy S
  • Created on: 28-04-13 10:35


  • Inheritance is the transfer of genetic information from generation to generation.
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  • A gene is a section of a DNA molecule that controls the development of certain characteristics.
  • Genes are located on chromosomes.
  • Genes control production of specific proteins in a cell.
  • Different genes code for different physical characteristics.
  • Each gene comes in at least 2 forms called alleles.
    • Each allele codes for different forms of the same character. e.g. attached/unattached earlobes.
      • Some alleles are dominant. (character they code for shows in appearance of individual, whether he/she inherits 1 or 2 of the alleles.
      • Other alleles are recessive. (character they code for shows in appearance of individual only if allele is present on both chromosomes.)
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  • Nucleus of a cell contains the chromosomes.
  • Chromosomes are made up of DNA.
  • Chromosomes are visible through a microscope during cell division.
  • 46 chromosomes in nucleus of human cell. (diploid number).
    • Each arranged as 23 matching (homologous) chromosomes.
      • In 22 of the pairs both chromosomes are the same shape & size.
      • 23rd pair are the sex chromosomes.
        • The sex of a person is controlled by this pair of chromosomes, XX in females & XY in males.
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