genetics

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  • genetics
    • genetic terms
      • inside a cell
        • when gametes fuse at fertilisation they form a diploid zygote
          • each zygote inherits different alleles of their genes from their parents
        • there are 2 copies of each chromosome in body cells
          • each copy has the same genes in the same order along its length
        • a gene is a short piece of DNA at a particular point on a chromosome
      • alleles
        • chromosomes of the same pair have the same genes in the same order
        • the same allele on each chromosome means the person in homozygous
        • different alleles of the same gene means the person is heterozygous
      • genetic definitions
        • genotypes show the alleles in the individual
        • the effect of the recessive allele will only show when two copies are present in the genotype
        • phenotype means the characteristics that are produced including what the individual looks like
        • the effect of the dominant allele will show when at least one copy is present in the genotype
    • genetic inheritance
      • Some characteristics are controlled by a single gene, such as fur in animals and red-green colour blindness in humans.
      • One chromosome of each pair is inherited from the mother and the other one is inherited from the father.
    • genetic variations and mutations
      • causes of variation that influence phenotype include genetic variation and environmental variation
      • genetic variation happens through mutation.
      • a mutation or genetic variant is created if the sequence of bases in the genes is changed
      • a mutation in the gene's coding DNA can affect the phenotype of an organism

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