Part B · Changing inherited traits Natural selection and genetic modification mind map

Selective breeding

• Human choice: Select inherited traits from existing variation
• Generations: Choose parents → breed → select offspring → repeat
• Goals: Yield, resistance, flavour, growth or milk production
• Inbreeding: Lower diversity; harmful recessive alleles may pair
• Vulnerability: Similar susceptibility can increase pathogen impact
• Welfare: Extreme selected traits can harm health and movement

Gene engineering

• Modification: Introduce a useful gene; transfer can cross species
• Cut: Restriction enzyme cuts gene-containing DNA and plasmid
• Vector: Plasmid carries the gene into the recipient
• Join: Complementary sticky ends pair; ligase joins backbones
• Transfer: Identify recipients; grow them; collect expressed protein
• Distinct roles: Restriction cuts; ligase joins; gene gives protein instructions

Applications

• Insulin: Engineered bacteria produce human insulin for purification
• Golden Rice: Beta-carotene production → vitamin A in the body
• Silk research: Engineered goats produce spider-silk proteins in milk
• Crop benefits: Nutrition, pest resistance and yield depend on trait / context
• Ecology: Gene spread to compatible relatives; test non-target effects
• Evaluation: Evidence: safety, biodiversity, welfare, cost and access

Connections

• Selective breeding → Gene engineering: Selection uses existing variation; engineering transfers genes.
• Gene engineering → Applications: Transferred genes provide useful protein instructions.