Variation

• Variation is differences in the characteristics of individuals in a population.
• Variation can be caused by genetics, environment or a combination.
• New phenotypes occur from mutation.
• Most mutations have no effect on phenotype, some influence phenotype, very few lead to a new phenotype.
• Selective breeding is breeding plants and animals for particular characteristics.
• The process of selective breeding:

  1. Choose parents with the desired characteristic.
  2. Breed them together.
  3. Choose offspring with the desired characteristic and breed again.
  4. Continue over many generations until all offspring show the desired characteristic.
• The consequences of inbreeding are inherited defects and diseases.
• Genetic engineering is modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic.
• Plant crops have been genetically engineered to:

  Be resistant to diseases/herbicides/pesticides.

  Produce bigger fruits.

  Give higher yields.
• Concerns about genetically engineered crops include:

  Detrimental effects to wild flowers and insects.

  Effects on human health may not be fully understood.
• Enzymes are used to cut out the required genes in genetic engineering.
• To transfer the required gene into a new cell for genetic engineering a vector is used (e.g. bacterial plasmid or virus)
• Bacteria have been genetically engineered to produce useful substances, such as human insulin to treat diabetes.