Selective breeding and genetic engineering: Inheritance, variation and evolution: Biology: GCSE (9:1)

• Selective breeding


  Also known as artificial selection, the process by which humans breed plants and animals for particular genetic characteristics

  
• Origins of selective breeding

  Humans have been selectively breeding organisms for thousands of years since they first bred food crops from wild plants and domesticated animals

  
• Selective breeding in plants

  Weeds have been selectively bred to make crops such as maize for corn, the wild mustard plant has been bred to make broccoli, kale and sprouts

  
• Selective breeding in domesticated animals

  Cattle and poultry have been selectively bred to be larger and produce more meat, dogs have been bred from wolf ancestors to be gentle or to have puppy-like features

  
• Early stages of selective breeding

  Parents with desired characteristics are selected from a mixed population to breed, some of their offspring should have desirable features similar to the parents

  
• Later stages of selective breeding

  The offspring with the most desirable characteristics are again selected to breed, this process continues for many generations until all organisms show the desired traits

  
• Benefits of selective breeding

  Disease resistance in food crops, animals which produce more meat or milk, domestic dogs with gentle natures, large or unusual flowers

  
• Risks and disadvantages of selective breeding

  Inbreeding which can severely affect an organism's lifestyle, reduces plant biodiversity, encourages disease-resistant weeds, raises ethical concerns

  
• Inbreeding


  A consequence of selective breeding where some breeds are particularly prone to disease, deformities or inherited defects

  
• Genetic engineering


  A process which involves modifying the genome of an organism by introducing a gene from another organism to give a desired characteristic

  
• Genome

  The entire genetic composition of an organism

  
• Genetic engineering in plants

  Plant crops have been genetically engineered to be resistant to diseases or produce bigger and better fruits

  
• Genetic engineering in bacterial cells

  Bacterial cells have been genetically engineered to produce useful substances such as human insulin to treat diabetes

  
• Process of genetic engineering

  Genes from chromosomes of humans and other organisms are cut out and transferred to the cells of other organisms

  
• Genetically modified (GM) crops


  Crops that have been genetically engineered to have desired traits, GM crops can have higher yields or can be resistant to insects or herbicides

  
• Benefits of genetically-engineered crops

  Crops such as golden rice can prevent vitamin deficiency, larger crops can help achieve food security, some GM crops do not need to be sprayed with chemicals

  
• Medical benefits of genetic engineering

  Insulin can be extracted without harming animals that are traditional sources of insulin, there is a future possibility of treating inherited disorders

  
• Risks and disadvantages of genetic engineering

  GM crops may affect biodiversity of insects and wild flowers, risk of superweeds, raises ethical issues, effects on human health are not fully explored