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UNIT 3 (Traits and genes (Alleles are the different alternatives that the…

- - - - Genetic biochemical tests: they study certain enzymes that can cause disorders when they are deficient.
      - Molecular tests
      - Cytogenetic tests: They consist on studying the function and structure of chromosomes.
  - - - Haemophilia
      - Muscular dystrophy
      - Down's syndrome
  - - - According to the effect on the individual
        
        Beneficial: They benfit an individual's survival that result in genetic variability.
        
        Neutral: These are mutations that do not affect the survival of the individual.
        
        Harmful: They affect the basic structures of the individual and can cause death.
      - According to the cells they affect
        
        Germline: They affect germ cells that originate in the sex cells.
        
        Somatic: They affect somatic cells. When they multiply, the resulting cells carry mutation.
      - According to the size of the mutation
        
        Gene mutations: They cause changes in the sequence of nucleotides in a specific gene.
        
        Chromosomal mutations: they cause changes in the structure of chromosomes.
        
        Genomic mutations: they originate during meiosis and result in a change in the individual's chromosome count.
- - - - A homologous segement, where the genes that control the same traits in the X and Y chromosomes are found.
      - A differential segment, where the genes belonging to the chromosomes X or Y are found.
    - - Colour-blindness: inability to distinguish between red and green. Produced by recessive genes located in the X chromosome.
      - Haemophilia: failure of the blood to clot. Produced by recessive genes located in the X chromosome.