Module 4 Bio

• Species


  A group of organisms able to reproduce to produce live fertile offspring
• Seven groups of classification

  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• Classification systems

  • Used to identify species, to predict characteristics, and to find evolutionary links
• Three domains

  • Archae
  • Bacteria
  • Eukarya
• Binomial nomenclature

  Involves the genus and the species name
• Five kingdoms

  • Prokaryotae
  • Protoctista
  • Fungi
  • Plantae
  • Animalia
• Prokaryotae


  • Unicellular, no nucleus (circular loop of DNA) or membrane-bound organelles, small 70s ribosomes, get nutrients either via absorption through cell wall from the environment or by photosynthesis, peptidoglycan cell wall
• Protoctista


  • Mainly unicellular, a nucleus and other membrane-bound organelles, some have chloroplasts, some don't move, amoeba move by spreading, some move by mechanisms e.g. flagella, can be heterotrophic, autotrophic, or parasitic
• Fungi


  • Unicellular or multicellular, membrane-bound organelles including nucleus, cell wall composed of chitin, no chloroplasts or chlorophyll, multicellular fungi have a body made up of threads or hyphae, nutrients aquired by absorbing decaying material (saphrophytes), food stored as glycogen
• Plantae


  • Multicellular, nucleus and membrane-bound organelles, cellulose cell wall, chlorophyll, immobile, photosynthesise, store food as starch
• Animalia


  • Multicellular, nucleus and other membrane-bound organelles, mobile, ingest nutrients (heterotrophic), store food as glycogen, move via muscle contraction
• There is the potential for six kingdoms due to difference in bacteria - these would be eubacteria and archae-bacteria
• Archae-bacteria


  • Able to live in extreme environments, don't have a peptidoglycan cell wall, and their ribosome structure is similar to eukaryote ribosomes
• Eubacteria


  • Live in all environments
• Phylogeny


  Evolutionary relationships between organisms
• Phylogenetics


  Study of phylogeny
• Organisms are now classified with consideration of their evolutionary relationships, using data from DNA/protein sequences and fossils
• Two descendants from the same branch


  Sister groups
• Phylogeny


  • Useful for confirming organism classification, considers how long ago organisms evolved, and doesn't equivocate organisms with different organisms or older organisms - this makes it superior to the taxonomic system
• Comparative anatomy


  Comparing the body structures of different species
• Homologous structures


  Structures that are integrally the same, but appear different on the surface
• Divergent evolution


  Individuals in one species adapt to become different species due to different environments
• Deeper fossils are more simple, while shallow fossils are complex, indicating the increase in organism complexity
• Animals without a skeleton don't fossilise, and volcanoes have destroyed fossilisation
• Homologous structures show that common structures adapt to serve different functions in different environments, due to divergent evolution
• Cytochrome C is a protein used during anaerobic respiration, found in virtually all eukaryotes. This means that the amino acids within it are usually the same throughout organisms, however a number aren't critical and change between species. Comparing these uncritical amino acids via comparative biochemistry indicates organism similarity
• Niche


  A role an organism plays in its environment, e.g a producer/predator/decomposer
• Niche includes the role an organism plays: Biotic interactions (food and predators), Abiotic interactions (gases breathed or sunlight absorbed)
• Two different species trying to occupy the same niche will out-compete one another until only one species survives
• To increase the chance of survival, organisms will be adapted to the niche that they occupy
• Convergent evolution


  Organisms in different taxonomic groups can develop similar characteristics because they have evolved in similar environments
• Marsupial moles and placental moles

  • Both burrow for food, so have powerful front paws and claws and have cone-shaped heads to push through the soil. However, they are distantly related and evolved in different continents
• Genotype


  Genes that code for a particular trait
• Phenotype


  Displayed characteristics
• Gene pool


  All the alleles within a population
• Gene flow


  Organisms joining a population
• Natural selection


  The process by which species evolve
• Evolution


  The change in allele frequency within a population over time
• Selection pressures


  Causes a particular characteristic to be more favourable in certain environmental conditions
• Natural selection

  1. Variation occurs in the population

  2. Organisms with advantageous alleles provide advantageous characteristics. They are more likely to survive and reproduce, passing on these alleles to offspring (survival of the fittest)

  3. A greater proportion of individuals in the next generation inherit this advantageous allele. They are also more likely to survive and reproduce