6 inheritance , variation and evolution

• inheritance

  refers to a trait or variants encoded in DNA and passed from parent to offspring during reproduction
• Meiosis


  1. Chromosomes are halved

  2. Combined with new genes from sexual partner

  3. Produces unique offspring
• Gene mutations occur continuously
• Rare mutations can affect the functioning of the animal or plant

  Mutations may be damaging and lead to genetic disorders or death
• Rare mutations can affect the functioning of the animal or plant


  Very rarely a new mutation can be beneficial and consequently, lead to increased fitness in the individual
• Variation generated by mutations and sexual reproduction is the basis for natural selection; this is how species evolve
• Understanding of these processes has allowed scientists to intervene through selective breeding to produce livestock with favoured characteristics
• Once new varieties of plants or animals have been produced it is possible to clone individuals to produce larger numbers of identical individuals all carrying the favourable characteristic
• Genetic engineering


  Taking genes from one species and introducing them into the genome of another
• Genetic modification still remains highly controversial in spite of the huge potential benefits that this technology can offer