ch. 27 flashcards.txt

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ch. 27 flashcards.txt
2011-10-05 21:21:04
prokaryotes bacteria

breakdown of prokaryotes, parts, names, life cycles, etc.
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  1. one long "age of prokaryotes"
    the history of life on Earth is one long "age of projkaryotes" because prokaryotes have been subjected to natural selection in all kinds of environments, resulting in their enourmous diversity today.
  2. 3 key features of their biology:
    • -they are small
    • -they reproduce by binary fission
    • -they have short generation times
  3. Cell-Surface Structures
    • Cell wall:
    • -maintains cell shape
    • -protects the cell
    • -prevents it from bursting in a hypotonic environment
  4. Hypotonic environment:
    • they lose water and shrink away from their wall (plasmolyze), which can inhibit cell reproduction
    • ex: salt preserves food b/c it causes prokaryotes to lose water and not multiply
  5. Cell wall structure:
    • made up of peptidoglycan, polymer composed of modified sugars cross-linked by short polypeptides
    • function: envelopes the organism and anchors other molecules to it
  6. Archael cell wall:
    made up of polysaccharides and proteins, lack peptidoglycan
  7. Gram-stain:
    • determines what the cell wall is made up of
    • positive: more peptidoglycan
    • negative: less peptidoglycan and are more complex, outer membrane that contains lipopolysaccharides (toxic, cause fever, and is protected from body's defenses)
  8. Penicillin:
    effectiveness derives from their inhibition of peptidoglycan cross-linking, making cell walls non-functionable
  9. Capsule:
    • -sticky layer of polysaccharides or proteins that surround the cell wall (well defined)
    • -allows the prokaryote to adhere to their substrate or other individuals in a colony
    • -some protect against dehydration
    • -some shield from pathogenic attacks from host's immunity system
    • Slime layer:
    • same thing but less organized
  10. Fimbriae:
    • hairlike appendages that allow the prokaryotes to stick to substrate or one another
    • shorter and more numerous than pili
  11. Pili:
    appendages that pull two cells together prior to DNA transfer from one cell to the other
  12. Taxis:
    a directed movement toward or away from a stimulus
  13. Flagella:
    • may be scattered around the entire surface or concentrated in one area
    • Different from eukaryotic flagella: p. flagella are one-tenth the width of e. flagella and p. flagella do not have plasma membrane
    • Different molecular composition: composed of diff proteins from eukaryotes and archaeal
    • analogous in structure
  14. Flagella parts: (composed of 42 diff kinds of proteins)
    • half the proteins are needed for the flagella, while the rest are needed for other parts of bacteria
    • -hook: comes out of the motor, and attaches to the filament
    • -motor: set of rings, makes the flagella propel
    • -filament: curly q
    • suggests exaptation: the process in which existing structures take on new functions through descent with modification
  15. P. genome:
    • -less DNA
    • -circular chromosome with fewer proteins than in linear chromosome of eukaryotes
    • -located in nucleiod, a region of cytoplasm that appears lighter than the surrounding cytoplasm in electron micrographs
    • -no membrane bound nucleus
    • -smaller rings of independently replicating DNA molecules called plasmids with few genes
  16. P. ribosomes
    • -different from e. ribosomes b/c they are smaller and have diff protein and RNA content
    • -allows certain antibiotics to bind to the prok. and not euk.
  17. Binary fission:
    a single p. cell divides into 2 cells, which then divide into 4, 8, 16, and so on
  18. reproduction is limited:
    • -cell exhausts its nutrient supply
    • -poison themselves with metabolic waste
    • -face competition with other microorganisms
    • -consumed by other organisms
  19. Endospores:
    • -resistant cells
    • -they are produced in original cell but water is removed and its metabolism stops
    • -protects them and they can sit dormant for centuries until environment improves
  20. *diverse adaptations exhibited by prokaryotes suggests that they must have considerable genetic variation
    • - comes from:
    • -mutation
    • -genetic recombination
  21. Asexual:
    -rapid reproduction and mutation may gave rise to their extensive genetic variation
  22. Mutation:
    • -rare; can increase genetic diversity quickly in species with short generation times and large populations
    • -this diversity can lead to rapid evolution
    • - (mutation →diversity →rapid evolution)
    • -if they are genetically better equipped to survive in their environment, then they rapidly multiply again
  23. Genetic recombination:
    the combining of DNA from two sources
  24. Horizontal gene transfer:
    prokaryotes from one species engage in transformation, transduction, and conjugation

    example: deadly strain in E. coli O157:H7 came from phage-mediated transduction. Adhesive fimbriae came from this transfer
  25. Transformation:
    • the genotype and possibly phenotype of a prokaryotic cell are altered by the uptake of foreign DNA from its surroundings
    • -a harmless strain of bacteria can combine with bacteria that has pathogenic alleles and become harmful
    • -cell surface proteins that recognize DNA from closely related species and transport it
  26. Transduction:
    • phages (virus that infects bacteria) carry prokaryotic genes from one host cell to another
    • -virus can't replicate because it lacks its own genetic material, but can inject it into another host
  27. Conjugation:
    • DNA is transferred between two prokaryotic cells (usually of the same species) that are temporarily joined
    • -one way street: one cell donates, the other receives
    • -example:
    • E. coli extends a pilus to another cell and sends DNA through pilus
    • -in order to donate DNA and have pili, the cell must have the F factor piece of DNA
    • -it can exist as a plasmid or a segment of DNA
  28. F factor as a Plasmid
  29. F Plasmid:
    • F factor in its plasmid form
    • -cells with it in this form function as DNA donors during conjugation (F+ cells)
    • -recipient during conjugation, F-
    • -F- can be changed to F+ if a copy of the entire F+ plasmid is transferred
  30. F Factor in chromosomes:
    • -Hfr Cells: high frequency of recombination; cells with F factor in chromosomes
    • -chromosomal genes can be transferred if the donor cell is a Hfr cell
  31. R Plasmids:
    • carry resistance genes to certain antibiotics such as tetracycline or ampicillin
    • -the more they resist to antibiotics, the more they multiply and evolve to resist treatment even more so
  32. *extensive genetic variation is shown in diverse nutritional adaptations
  33. Phototrophs:
    get nutrition from life
  34. chemotrophs:
    get energy from chemicals
  35. autotrophs:
    need only CO2 in some form as a carbon source
  36. hetertrophs:
    require at least one organic nutrient to make other organic compounds
  37. Photoautotrophs
    • -need light for energy
    • -need CO2 as a carbon source
    • example: cyanobacteria, algae
  38. chemoautotrophs
    • -need inorganic molecules for energy (iron, etc)
    • -need CO2 for carbon
    • Example: sulfolobus
  39. photoheterotrophs:
    • -need light for energy
    • -need organic compounds for carbon
    • Example: certain aquatic/salt loving prokaryotes; rhodobacter, chloroflexus
  40. chemoheterotrophs:
    • -need organic compounds for energy
    • -need organic compounds for carbon
    • Example: clostridium; some fungi, animals, and plants
  41. obligate aerobes:
    must use O2 for cellular respiration and cannot grow without it
  42. Obligate anaerobes:
    are poisoned by O2; some live exclusively by fermentation
  43. anaerobic respiration:
    substances other than O2, such as nitrate ions or sulfate ions, accept electrons at the "downhill" end of electron transport chain
  44. Facultative anaerobes:
    use O2 if it is present but can also carry out fermentation or anaerobic respiration in an anaerobic environment
  45. *nitrogen is essential for the production of amino acids and nucleic acid in all organisms
  46. nitrogen fixation:
    • some cyanobacteria and methanogens will convert atmospheric nitrogen to ammonia
    • -self sufficient organisms
    • -can help increase the availability of nitrogen for plants through ammonia produced by prokaryotes, since plants cannot absorb it from atmosphere
  47. metabolic cooperation:
    • -some cells (cyanobacteria, Anabaena) have enzymes for photosynthesis and nitrogen fixation, but can't carry out both together- hence, cooperation among other cells called filamentous chains
    • -most cells in a filament are photosynthetic
    • -heterocysts: filament cells carry out nitrogen fixation only
    • -thickened cell wall that keeps oxygen out, can transport nitrogen to neighbor cells and receive carbohydrates
  48. Biofilms:
    • surface-coating colonies of prokaryotes of different species engaging in metabolic cooperation
    • -secrete signaling molecules to recruit more cells
    • -also secrete polysaccharides and proteins to stick to one another
    • -have channels for nutrients and to expel waste
  49. molecular systematics:
    ribosomal RNA was used as a marker, Carl Woese concluded that some bacteria are more closely related to eukaryotes, hence archae
  50. Metagenomics:
    analyzing genes using polymerase chain reactions in prokaryotes collected from the environment
  51. extremophiles:
    prokaryotes that live in extreme conditions including extreme halophiles and thermophiles
  52. halophiles:
    they live in highly saline environments; have cell walls that function best in highly saline areas
  53. thermophiles:
    they live in very hot environments; such as sulfolobus that live in sulfur-rich volcanic springs
  54. Methanogens:
    • archae that release methane as a byproduct of their unique ways of obtaining energy
    • -use CO2 to oxidize H2
    • -strict anaerobes
    • -live in anaerobic environments such as inside guts of cattle and termites and decomposers in sewages
  55. Euryarchaeota:
    containing halophiles, methanogens, some thermophiles
  56. Crenarchaeota
    most thermophiles
  57. Korarchaeota
    archaea found in a hot spring in Yellowstone
  58. Nanoarchaeota
    • in Iceland, there were small archaea attached to larger crenarchaeota
    • three places: hot spring in yellowstone, hot spring in siberia, one from hydrothermal vent in the pacific
  59. Proteobacteria
    • -alpha
    • -beta
    • -gamma
    • delta
    • -epsilon
    • Chlamydias
    • Spirochetes
    • Cyanobacteria
    • Gram-positive Bacteria

    Prokaryotes play crucial roles in the biosphere
  60. Chemical recycling:
    decomposers: chemoheterotrophs that break down dead organisms as well as waste products and unlocking supplies of carbon, nitrogen, and other elements
  61. Cyanobacteria:
    • -use CO2 to make organic compounds
    • -produce atmospheric O2
  62. increase availability of nutrients in plants:
    nitrogen, phosphorous, potassium
  63. decrease in nutrients:
    immobilize nutrients by using them to synthesize molecules that remain within their cell walls
  64. symbiosis:
    • an ecological relationship in which two species live in close contact with each other
    • -usually happens with a larger organism- host
    • -smaller is the symbiont
  65. mutualism:
    an ecological interaction between two species in which both benefit

    example: bioluminescent bacteria in deep sea fish
  66. commensalism:
    an ecological relationship in which one species benefits while the other is not harmed or helped in any way

    example: bacteria that live on our skin. we provide them with food and a place to live, they do not harm or help us
  67. parasitism:
    • an ecological relationship in which a parasite eats the cell contents, tissues, or body fluids of its host; harm but do not usually kill
    • -those that cause disease are called pathogens
  68. Mutualistic bacteria:
    -our intestines; signals from the bacterium activate human cells to produce antimicrobial compounds to which B. thetaiotaomicron are not susceptible
  69. Pathogenic bacteria:
    • -tuberculosis caused by mycobacterium tuberculosis
    • -Lyme disease caused by bacteria that lives in ticks
  70. Exotoxins:
    • proteins secreted by certain bacteria and other organisms
    • -cholera caused by Vibrio cholerae
    • -botulism caused by Clostridium botulinum
  71. Endotoxins:
    • -lipopolysaccharide components of the outer membrane of gram-negaive bacteria
    • -released when the bacteria dies and their cell walls break down
    • -Salmonella
  72. Virulence:
    turning normally harmless bacteria into harmful ones
  73. *gene cloning applications
    • *milk to cheese and yogurt
    • *can be made into biodegradable plastic
  74. bioremediation:
    • the use of organisms to remove pollutants from soil, air, or water
    • -breaking down landfills, cleaning up oil spills, precipitating radioactive material out of ground water