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prokaryote notes

prokaryote notes



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    Bacteria Bacteria Presentation Transcript

    • Ch. 19 - Bacteria and Viruses Chapter 19
    • 19-1 Bacteria • Common name for all prokaryotes • unicellular organisms without a nucleus • Were all in Monera • Eubacteria • live nearly everywhere • normally protected by cell wall containing peptidoglycan - cell membrane inside of cell wall
    • • Archaebacteria • lack peptidoglycan • DNA similar to eukaryotic DNA • most are extremophiles – live in harsh environments • methanogens; halophiles; extreme thermophiles
    • Prokaryotic Body Plan pilus DNA bacterial flagellum capsule plasma membrane cell wall ribosomes in cytoplasm cytoplasm
    • Identifying Prokaryotes 1. Shape a. bacilli(us) – rod-shaped b. cocci(us) – spherical c. spirilla(us) – spiral and corkscrew shaped 2. Cell Walls a. Gram-positive – have thick peptidoglycan cell walls that take and hold stain b. Gram-negative – thinner cell walls with lipids on outside – does not hold stain Gram Positive Gram Negative 3. Movement
    • Metabolic Diversity 1. Chemoheterotrophs – must take in organic molecules for energy and a supply of carbon 2. Photoheterotrophs – use photosynthesis for energy, but take in organic compounds for carbon source 3. Photoautotrophs – use photosynthesis for both energy and carbon source 4. Chemoautotrophs – use chemosynthesis – get energy from chemical reactions and use carbon dioxide as carbon source
    • Releasing Energy - bacteria release energy by cellular respiration and fermentation A.Obligate Aerobes - require a constant supply of oxygen B. Obligate Anaerobes - must live in the absence of oxygen C. Facultative Anaerobes - can survive with or without oxygen
    • Growth and Reproduction - under good conditions bacteria can reproduce every 20 minutes Binary Fission - normal asexual reproduction of bacteria - replicate DNA and then divide Conjugation - exchange of genetic material between bacterial cells - increases genetic diversity Spore Formation - allows survival of bad conditions for a long time
    • Prokaryotic Fission - 1 bacterial chromosome Bacterium before DNA replication DNA replication begins Figure 21.7 Page 350
    • Prokaryotic Fission - 2 parent DNA molecule DNA replication completed DNA copy Membrane growth moves DNA molecules apart
    • Prokaryotic Fission - 3 New membrane and cellwall material deposited Cytoplasm divided in two
    • nicked plasmid in donor cell Conjugation Transfer of plasmid conjugation tube to recipient cell
    • Importance of Bacteria - while we usually think of bacteria negatively they are actually essential to correct functioning in ecosystems A. Decomposers - primary decomposers who make nutrients available to plants - used in sewage treatment plants also B. Nitrogen Fixers - Rhizobium in nodules of legume roots fix nitrogen in a form the plants can use
    • C. Human Uses • in food production • in industry – can clean-up oil spills • to synthesize drugs and chemicals • genetic engineering now has them producing human hormones • Mutualism with Eschecaria coli in our colon where they help us make vitamins