natural selection/ genetic modification

• Natural selection


  Survival of the fittest - animals that are better suited to the environment survive and those that are not die off
• Stages of natural selection


  1. Variation

  2. Natural selection

  3. Inheritance

  4. Evolution
• Variation

  • Naturally occurring differences within a species due to genetics and environment
• Evolution

  • Animals not suited to the environment die off, leaving the adapted ones to survive and reproduce
• Darwin and Wallace


  Scientists who came up with the theory of evolution
• Evidence for evolution

  • Bacteria developing antibiotic resistance
  • Human fossils showing gradual change
• Five kingdoms to classify living things

  • Animals
  • Plants
  • Fungi
  • Prokaryotes
  • Protists
• Three domain system

  More broad classification of organisms based on genetic analysis

  
  

  Archaea-no nucleus, unused sections of genes

  bacteria - no nucleus, no unused sections of genes

  eukarya - nucleus, unused sections of genes
• Selective breeding

  Breeding parents with desired characteristics to produce offspring with those traits
• Selective breeding can reduce the gene pool and cause health problems
• Tissue culture

  Growing cells in a lab to clone plants or test medicines
• Genetic modification is fast and easy but expensive, and the modified genes could spread to the environment
• Darwin studied finches- they have different beaks to eat different foods
• how do antibiotics work?

  damage bacteria's cel wall

  without affecting host cell
• main stages of antibiotic resistance (via natural selection)

  . random mutation in gene

  . mutation protects bacterial cell from the effects of antibiotic

  . bacteria without mutation die

  . resistant bacteria survive due to advantageous mutation. . . .

  . reproduce

  . gene for resistance passed to offspring

  . new antibiotic resistance species formed
• why an antibiotic would not work for a disease

  only used to treat BACTERIAL disease NOT viral/ fungal diseases
• how do you prevent antibiotic resistance

  prevent over use

  complete full course

  take correct dosage at regular times
• what do stone tools provide evidence for

  that humans evolved and became more skilled overtime as stone tools get more advanced as time goes on.
• classification

  grouping organisms depending on their structure and characteristics
• desired characteristics in plants

  increases crop yield

  produces disease resistant crops
• desired characteristics in plants


  cows which produce more milk

  chickens with larger eggs
• steps of selective breeding

  identify desired characteristic

  select individuals with the desired characteristics

  breed together

  select offspring with desired characteristics

  breed together

  repeat
• advantages of selective breeding


  produces better quality food

  animals can be selected that cant cause harm e.g cattle without horns
• genetic engineering/ modification


  altering genome of organism often by adding genes from another species
• genetic engineering for medical reasons?

  genetically engineering bacterial cells to produce human insulin
• gm in agriculture


  genetically modifying crops to be resistant to herbicide allows them to tolerate herbicide but weeds are killed by it so less herbicide is needed
• gm in food industry


  golden rice- scientists have added a gene to wild rice that makes it produce beta carotene which is needed by humans in order to make vitamin a which is essential for good vision
• steps of gm


  restriction enzymes are cut out desired gene leaving it with sticky ends.

  a vector (bacterial plasmid or virus) is cut by the same restriction enzyme leaving it with complimentary sticky ends

  vector and the cut desired gene are joined by ligase enzyme

  vector (bacteria/ virus) inserts gene into required cells