B14- genetics and evolution

• What is a fossil

  Remains of organisms from millions of years ago found in rocks
• how are fossils formed

  1. when parts of organisms have not decayed - conditions for decay absent - too cold, not enough oxygen or not enough water
  2. If parts of organism are slowly replaced by minerals in decay process
  3. Preserved traces of organisms - footprints, burrows or preserved places where roots once were
• why are fossils not reliable

  • soft bodies organisms don’t form fossils
  • fossils have been destroyed by changes to rocks in earths crust
  • cannot be certain when life on earth began
• what is extinction

  when no remaining individuals of a species are alive
• how can species become extinct

  1. catastrophic events - asteroid
  2. environment changes - weather patterns
  3. new disease or predator
  4. new, more successful species evolves and competes with it - scare food or water
• How quick can bacteria reproduce

  Under ideal conditions every 30 minutes - can evolve rapidly
• when did doctors begin to use penicillin

  1940s
• what do antibiotics do

  kill bacteria
• what is antibiotic resistance

  when certain strains of bacteria are not killed by antibiotic - evolved
• Example of an antibiotic resistant strain of bacteria

  MSRA
• how does antibiotic resistance happen

  1. bacteria are pathogens and cause disease
  2. in every population there is variation due to mutation
  3. mutation could make a bacterium resistant to antibiotics
  4. when an antibiotic is taken all of the bacteria are killed apart from the resistant bacterium
  5. the resistant strain survives and reproduces without any competition from other bacteria
  6. over time the population of the resistant strain rises
  7. the resistant strain spreads as people are not immune and no effective treatment
• how can we reduce the development of antibiotic resistant strains

  1. don’t prescribe antibiotics inappropriately - viruses
  2. Patients make certain to complete course of antibiotics - all bacteria killed- non survive and able to mutate
  3. Restrict use of antibiotics in farming
• problems with producing new antibiotics

  • takes a long time
  • expensive
  • unlikely to keep up with resistant strains
• what is Linnaeus classification

  • 1700s carl Linnaeus
  • Divided all living organisms into 2 kingdoms - animal and plant
• Mneunomic for Linnaeus classification

  King (kingdom)

  Phillip (phylum)

  Came (class)

  Over (order)

  For (family)

  Good (genus)

  Soup (species)
• What is the binomial system

  • Each organise is named from their genus and species
  • Genus capital latter
  • Species lower cases
• what is the three domain system

  • carl woese
  • Compared biochemistry of different organisms
• what are archae

  primitive bacteria often found in extreme conditions such as hot springs
• what are true bacteria

  live in digestive system
• what are eukaryota

  animals, plants, fungi and protists
• what are evolutionary trees

  • using classification data on living organisms - dna
  • uses fossils for extinct species
  • fossil records are incomplete for many species
  • shows how closely related species are