Natural Selection

• Variation


  Each individual has a different phenotype
• Genome


  The entire genetic material of an organism
• Phenotype

  Your observable characteristics. These can be changed by the environment and come from your genes.
• Genes

  Code for proteins
• Everyone has a unique genome, except identical twins, so they have a different combination of proteins inside them, creating variation.
• Most of our characteristics are determined on how our genes interact with our environment
• Genetic variation

  Caused by mutations. Most mutations have no affect on proteins so there is no change to the phenotype.
• Beneficial mutations

  Can make someone live longer and allow someone to reproduce more. This is known as survival of the fittest.
• Traits

  Passed on by parents, usually the useful ones
• Natural selection

  When the fittest individuals are selected to survive
• Evolution

  Inheritance of certain characteristics in a population, over multiple generations, could lead to a change in the whole species. Or sometimes the development of an entirely new species
• Current species must have evolved from simple life forms that developed more than 3 billion years ago.
• Antibiotic resistance is an example of evolution
• Selective breeding

  1. Select two parents which have the characteristics you are after, which will produce even better offspring

  2. Do this again and again, choosing the best parents and producing even better offspring
• Gene pool

  Collection of different alleles in a population
• Selective breeding reduces gene pool of the population
• The best individuals are closely related. This can cause the offspring to be prone to diseases or have inherited defects due to a smaller gene pool
• A small gene pool also means less variation in the population. This means a disease could affect all of them at once
• Fossils

  What organisms have left behind, showing how organisms have changed providing evidence for evolution
• 3 main ways fossils form

  1. Gradual replacement by minerals

  2. Casts

  3. Impressions
• Preservation

  Fossils can form by preservation too, where there is no decay at all.
• We still do not know how life first developed, because many early life forms were soft bodied, so they decayed really quickly, making fossil remains really unlikely
• Fossils formed could have also been destroyed, due to volcanic activity, earthquakes and more larger geological activity like the movement of tectonic plates.
• Extinction

  When no individuals of a specific species remains
• Causes of extinction

  • Environment changes too quickly
  • Habitat is cut down
  • Planet gets too warm too quickly
  • Predators
  • New disease
  • New species outcompetes previous one
  • Catastrophic event
• For any organism to survive, they must be adapted to their environments.
• Classification

  Grouping species together due to their characteristics and bone structure.
• Binominal naming system

  Naming an organism with their genus and species names
• Three Domain System

  • Bacteria
  • Eukaryota
  • Archaea
• Pentadactyl limbs can indicate that different species may have evolved from a common ancestor.
• Taxonomic levels

  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• Dear Kate, please come over for great spaghetti
• Antibiotic resistance

  A random mutation in the DNA of a bacteria, causing it to become resistant to the bacteria
• Antibiotics

  A group of drugs that can kill bacteria
• Because antibiotics have been used for so long, some bacteria have become resistant to it. Overuse causes this too.
• Antibiotic resistance strain

  The resistant bacteria multiplying and reproducing via asexual reproduction, making a colony of bacteria containing the resistant mutation
• When antibiotics lose their effectiveness

  You would still be infected. You can then pass these bacteria onto other people, and if they go to the doctor and receive the same antibiotic, it won't work on them either.
• Superbugs

  Bacteria resistant to loads of antibiotics. Can be fatal
• Super uncommon for bacteria to develop resistance, and if they do it is partial resistance
• Antibiotic courses should be FULLY completed