topic4 natural selection

• Carl Linnaeus (1707-1778) suggested that humans were related to apes and monkeys
• Binomial names are created from an organism's genus and species
• Fossils are the preserved remains of organisms that lived on Earth thousands or millions of years ago
• The fossil record is a collection of fossils from different periods in Earth's history, showing how organisms have changed gradually through time
• Gaps in the fossil record are due to soft-bodied organisms leaving little fossil evidence, destruction of hard parts of organisms, and many fossils being buried deep and not yet found
• Scientists discovered 4.4 million year old fossilised bones from a female of an extinct human-like species named Ardi
• Different human-like species include Ardi, Lucy, Homo habilis, Homo Erectus, and Homo sapiens with varying heights, brain sizes, and characteristics
• Stone tools date back 3.3 million years ago, with more recent tools found in more sophisticated forms
• Brain size has increased over the evolution of human-like species, suggesting more complex central nervous systems
• Human-like species have evolved into walking upright and using tools, providing benefits such as better visibility, free hands for tasks, and less exposure to sunlight
• Natural selection is the process where organisms slowly evolve into others over time
• Wooly mammoths and elephants evolved from a common ancestor due to natural selection
• Warfarin resistance in rats and antibiotic resistance in bacteria are modern examples of natural selection
• Darwin's study of vertebrates' bone structure and the pentadactyl limb structure provide evidence for evolution
• Classification sorts organisms into groups based on characteristics, with the binomial naming system using genus and species names
• Scientists now use molecular phylogeny to track similarities in DNA, genes, and proteins to determine how closely related organisms are
• There are three domains: Archaea, Bacteria, and Eukarya, and five kingdoms including Animalia, Plantae, and Fungi
• Plants:

  • Make their own food through photosynthesis
  • Cell walls made of cellulose for support
  • Complex cell structure with nucleus
• Fungi:

  • Multicellular with cell walls not made of cellulose
  • Saprophytic feeders get food from dead or decaying matter
  • Complex cell structure with nucleus
• Protoctista:

  • Unicellular
  • Complex cell structure with nucleus
• Prokaryotae:

  • Unicellular
  • Simple cell structure with no nucleus
• No kingdom for viruses because:

  • Non-living
  • Not made up of cells with cell organelles
  • Can only exist inside 'host' cells (e.g. inside human cells)
• Living organisms in kingdoms are further divided into 6 sub-categories: Phylum, Class, Order, Family, Genus, and Species
• Natural selection:

  • Some individuals inherit characteristics that allow them to survive better in a certain area
• Artificial selection:

  • Humans choose organisms with useful characteristics
  • E.g. sheep with thick wool
• Selective breeding:

  • Used by farmers to achieve high-quality yield and enhance produce
  • Steps:

  1. Decide important characteristics

  2. Choose parents with these characteristics

  3. Select best offspring for next generation

  4. Repeat continuously
• Issues with selective breeding:

  • Narrows gene pool, affecting species survival
  • Increased risk of inheriting mutations
  • Animal welfare issues
• Genetic engineering:

  • Process of removing a gene from one organism and inserting it into another
  • Genetically modified organism (GMO) has genes from another species
  • Genome is all genetic information in an organism
  • Vector carries information
• Making GMOs:

  • Alter DNA to produce new proteins
  • Example: genetically modifying bacteria to produce insulin
  • Steps:

  1. Isolate gene using restriction enzymes

  2. Cut open plasmid from bacterial cell

  3. Insert human gene into plasmid using ligase enzymes

  4. Replace plasmid in bacterial cell

  5. Allow bacteria to reproduce in a fermenter

  6. Separate and purify the antibody
• 
  

  Sticky Ends

  • Restriction enzymes are used on both the desired section of DNA and the plasmid.
  • They make the same staggered cuts in DNA molecules, producing sections with a few unpaired bases at each end - 'sticky ends'.
  • The complementary bases on the sticky ends of the human gene and plasmid join
• GMO - Pesticide Resistant Plants:

  • Used to make plants resistant to herbicides or pesticides
  • Steps differ from insulin production
• Uses of GMOs:

  • Golden Rice for Vitamin A deficiency
  • Climate resistant crops
  • Toxin producing crops
  • Insulin production
• Advantages of GMOs:

  • Increases yield
  • Less use of chemical pesticides
  • Less harm to living things
  • Suitable for vegans
  • Reduce vitamin A deficiency cases
  • Large scale production of essential proteins like insulin
• Disadvantages of GMOs:

  • Unknown long term effects on human health
  • Expensive to produce and buy
  • Farmers in developing countries cannot afford
  • Cross-pollination produces 'superweeds'
  • Risks of culturing microorganisms
  • Reduces biodiversity
  • Greater competition between plant species
• Tissue culture:

  • Growing cells or tissues in liquid or on solid medium
  • Useful for growing identical cells
  • Used to make animal organs and new plants
• Making animal organs:

  • Tissue culture used to make synthetic organs
  • Growing cells in liquid containing nutrients
  • Useful for growing identical cells
• Making plant tissues:

  • Used for rare plant species or clones of GM plants
  • Stages:

  1. Cut plant sections or tissue sample

  2. Treat to kill microorganisms

  3. Place in agar plate with nutrient medium

  4. Develop roots and shoots under hormone influence

  5. Grow in sterile conditions

  6. Transfer to soil or compost
• Fertilisers:

  • Enhance crop yield with mineral ions like nitrogen, potassium, and phosphorus
  • Runoff can cause eutrophication and health problems
• Biological control:

  • Using other species to control pests and weeds
  • E.g. Chrysolina beetles to control St John's Wort
• Ardi (Ardipithecus ramidus)

  • Height - 120cm
  • Existed - 4.4 million years ago
  • brain size - 350 cm^3
  • other details - Chimpanzee-like features
  • discovered - 1992