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Genetics · Chapter 7: Biotechnology and DNA sequencing

Year 11 Science · About 20 minutes with activities · Turn your sound on

Chapter 7 · Biotechnology
Merinofiner wool
Dairy cowsmore milk
Kākāpōbreeding programme
Insulinmade by bacteria
Parents chosen for finer wool
Offspringmore desirable characteristics
Closely related parentsboth carry the recessive allele a
aa: two copiesthe harmful allele is expressed
Negative
Inbreeding depressiontwo copies of a recessive harmful allele
Reduced genetic diversityless able to survive a new disease
Unintended traitse.g. joint problems, reduced fertility
Positive
Finer wool, more milkNew Zealand agriculture
Disease resistancee.g. facial eczema in sheep
Conservationkākāpō and takahē breeding
Original
Genetically identical clones
Benefits
Revive extinct species
Desirable crops (e.g. seedless)
More consistent livestock output
Research into diseases and medicines
Concerns
No genetic diversityone new disease could wipe out clones
Inherited disordersdefects and shorter lifespans
Re-extinction riskhabitat loss and hunting not fixed
Low success rate, high cost
Insulin gene
Bacterium with the human gene
Insulin
Golden Ricea source of vitamin A
Benefits
Medicines: insulin, vaccines
Nutrient-rich crops (Golden Rice)
Pest, disease and drought resistance
Less pesticide and herbicide use
Concerns
Superweeds from cross-pollination
Ethics: playing God, patents
Health worries (most studies: safe)
A few corporations control seed
Gene drives: suggested for pest control, but ecological concerns
Chromatogramone coloured peak per base
Base sequence: ATGCCTAGGTCATTGC
DNA sequencing
Exact information, including mutations
Identifies carriers and silent mutations
Guides personalised medicine
No family history needed
Punnett squares & pedigrees
Only predictions
Need a family history
Need visible traits or offspring
Can’t detect carriers early
Mutation: A → Tthe patient carries a mutated allele
Blood or saliva → DNA sequenced → chromatograms compared
Carrier?
Carrier?
Thick, sticky mucus
Blocked lungs and digestive system
More lung infectionslower nutrient absorption
Both carriers? → genetic counselling

Chapter 7 recap

  • Selective breeding: choosing parents with desirable characteristics. Inbreeding: breeding close relatives. Positives: NZ agriculture and conservation. Negatives: inbreeding depression, reduced genetic diversity, unintended traits.
  • Cloning: a genetically identical copy. Transgenesis: a gene from one organism put into another’s genome. In a for-or-against answer, justify your stance with scientific implications.
  • DNA sequencing: the exact order of bases. Unlike Punnett squares and pedigrees, it finds mutations and carriers without family history, e.g. CDH1 (stomach cancer) and CFTR (cystic fibrosis).
  • You’ve finished all seven chapters. Kia kaha for your exams!

How do we change genes on purpose?

Chapter 7 · About 20 minutes · sound on

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