Bio 004,CH15, College of the Desert

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Bio 004,CH15, College of the Desert
2011-07-18 16:32:49
Chapter15 Bio4 College Desert Evelution Microbial Life

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  1. Cambrian Period
    • All major animal groups evolved before the end of the Cambrian Period.
    • Extensive animal diversity in 10 million years All major animal groups evolved before the end of the Cambrian period.
  2. Spontaneous Generation
    Belief that life arises from non-living material.
  3. Biogenesis
    • Principle in that life arises only by the reproduction of pre-existing life
    • In a series of experiments, Louis Pasteur proves biogenesis over spontaneous generation (1862).
  4. Origin of Life
    • Four Stage Hypothesis – Origin of Life
    • 1) The abiotic synthesis of small organic molecules (amino acids, nucleotides, etc.).
    • 2) The joining of small organic molecule into large organic molecules (polymers) forming proteins and nucleic acids.
    • 3) The origin of self-replicating molecules (RNA & DNA) that ultimately makes inheritance possible.
    • 4) The packaging of all these molecules into precursors to cells.
  5. Dehydration synthesis reactions
    Way in which organic molecules could have been synthesized around deep sea vents and lava flows.
  6. Prokaryotes
    • Prokaryotes [Bacteria]
    • A. General Characteristics
    • 1. Ubiquitous - outnumbering all other species
    • 2. Thrive in extreme conditions
    • 3. Responsible for serious illness
    • 4. Responsible for human existence
  7. Two Major Braches of Prokaryote Evolution
    • 1. Archaea
    • a) Extremophiles: thrive in extreme conditions (extreme heat, pH, salinity, etc.)
    • b) Methanogens: thrive in anaerobic conditions (digestive tracts of herbivores), producing methane gas.

    2. Bacteria Consist of the more familiar bacteria – those that interact directly or indirectly with humans.
  8. Bacteria Structure
    • 1. Most are unicellular and very small
    • 2. Nucleus/complex organelles absent
    • 3. Cell walls (different than plant cell walls)
    • 4. Occur in three basic shapes: coccus (round), bacillus (rod), and spirillum (spiral).
  9. Prokaryotes function
    • Endospores: Thick-coated protective cell produced within a bacterial cell when exposed to harsh conditions.
    • a. Remain dormant for centuries.
    • b. Can even withstand boiling water.
    • c. Example: Clostridium botulinum.
  10. Binary fission
    Asexual reproduction in which the parent cell divides into two cells of approximate equal size. Some bacteria populations double in size every 20 minutes; in 48 hours this would result in a colony consisting of 2.2 x 1043. Colonies are limited in size by the amount of natural resources and by the build-up of waste products.
  11. Pathogen
    • Disease-causing organism.
    • Exotoxins - poisonous proteins secreted by bacterial cells (example: Staphylococcus)
    • Endotoxins - poisonous chemical components within bacterial cells (example: Salmonella)
  12. Nutrition
    Prokaryotes derive energy from light and chemicals depending on their habitat.
  13. Saprophytes
    Organisms that break down dead and decaying organic material. Recycle nutrients back into living organisms. [decomposers]
  14. Bioremediation
    Use of organisms to remove pollutants from water, air, and soil.
  15. Eukaryotes Structure
    • 1. Unicellular to multicellular.
    • 2. Nucleus/complex organelles present.
    • 3. Cell walls present in algae, fungi, and plantsOccur in many diverse shapes.
  16. Endosymbiosis
    Close association of 2 species in which one lives inside another.
  17. Mitochondria & Chloroplasts
    • a) Contain DNA & RNA.
    • b) Synthesize proteins using ribosomesReproduce by binary fission.
  18. Protists
    Eukaryotic, unicellular organisms.
  19. Protozoans
    Animal – like protists
  20. Slime molds
    Fungus – like protists
  21. Unicellular algae
    • Plant-like protists (photo-synthetic)
    • a) Plankton: Communities of microscopic organ-isms that drift or swim near pond, lake, and ocean surfaces.
    • b) Diatoms: Unicellular algae with cell walls com-posed of silica (glass); diatomaceous earth
    • c) Green algae: Most closely related to green plants (ancestors?); possess cell walls and chloroplasts.
  22. Seaweeds
    Large, multicellular, marine algae. Grows along rocky shores and just beyond the surf with adaptations for existence. Classified based partly on pigments present: green, red, brown (kelp). Food source and as a thickening agent in pudding, ice cream, and salad dressing.