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Prokaryotes (Classification (Bacteria (Initiator amino acid for protein…

- - - - Chemoautotroph
        
        energy source from chemicals
        
        carbon source from CO2
      - Photoheterotroph
        
        energy source from light
        
        carbon source from organic compounds
      - Photoautotroph
        
        energy source from light
        
        carbon source from CO2
        
        cyanobacteria
        
        gram-negative photoautotroph that generates O2
      - Chemoheterotroph
        
        energy source from chemicals
        
        carbon source from organic compounds
  - - - No nucleus
      - No membrane bound organelles
      - Bacterial cell walls contain peptidoglycan
      - Archaeal cell walls contain polysaccharides and proteins
      - use specialized infolded regions of the plasma membrane to perform many metabolic functions, including cellular respiration and photosynthesis
    - - Nucleus present
      - Membrane bound organelles present
      - Cell walls contain cellulose or chitin
  - - - Obligate anaerobes
        
        are poisoned by O2 and live by fermentation or use substances other than O2 for anaerobic respiration
      - Facultative anaerobes
        
        can use O2 if it is present or carry out fermentation or anaerobic respiration if it is not
      - Obligate aerobes
        
        require O2 for respiration
    - - nitrogen fixation
        
        some prokaryotes convert nitrogen gas to ammonia
        
        ex: cyanobacteria Anabaena
        
        photosynthetic cells and nitrogen fixing cells called heterocycts exchange metabolic products
    - - an organism that produces methane gas
- - - - cocci (spheres)
      - bacilli (rods)
      - spirals
        
        spirilla (comma-like to long coil)
        
        spirochetes (corkscrew)
  - - - Most bacterial cell walls contain peptidoglycan
      - a polymer of modified sugars cross-linked by
        short polypeptides
      - Gram staining
        
        Gram positive
        
        bacteria have simple cell walls with large amounts of peptidoglycan
        
        Gram negative
        
        bacteria have more complex cell walls with less peptidoglycan
        
        outer membrane on the cell wall of gram-negative cells contains lipopolysaccharides, carbohydrates bonded to lipids
        
        generally more deadly than gram-positive species
        
        lipopolysaccharides on the walls of gram-negative bacteria are often toxic, and the outer membrane protects the pathogens from the defenses of their hosts
        
        commonly more resistant than gram-positive species to antibiotics because the outer membrane impedes entry of the drugs
        
        a valuable tool for identifying specific bacteria based on differences in their cell walls
    - - cell walls of archaea contain polysaccharides and proteins, but lack peptidoglycan
  - - - fimbriae
        
        surface appendage
        
        attachment pili
        
        another way for prokaryotes to adhere to one another or to the substratum
        
        usually more numerous and shorter than sex pili
        
        sex pili
        
        specialized for holding two prokaryote cells together long enough to transfer DNA during conjugation
  - - - flagella
        
        scattered over the entire surface or concentrated at one or both ends
        
        whip or tail-like appendage used to swim
      - taxis
        
        movement toward nutrients or oxygen (positive chemotaxis)
        
        movement away from a toxic substance (negative chemotaxis)
- - - - ex: bacteria are used to help clean up oil spills
        
        extremeophiles
        
        thermophiles
        
        live in very hot environments
        
        halophiles
        
        live in highly saline, salty environments
        
        archaea that live in extreme environments
  - - - ex: cheese
  - - - Humans or animals
        
        bacterial infections
        
        Antibiotics
        
        medication to combat bacterial disease
        
        ex: Lyme disease
        
        exotoxin
        
        secreted and cause disease even if the organisms that produce them are not present
        
        endotoxin
        
        released only when the bacteria die and their cell walls break down
      - Plants
        
        crop diseases
  - - - ex: bacteria in human gut help digest food
- - - - Conjugation
        
        Sometimes known as bacterial “sex,” conjugation transfers genetic material between two bacterial
        cells that are temporarily joined
        
        Part 1: Conjugation and transfer of an F plasmid
        
        Steps
        
        Donor and recipient cells synthesize complementary DNA strands
        
        One strand of F+ cell plasmid DNA breaks at arrowhead
        
        Recipient cell is now a recombinant F+ cell
        
        Broken strand peels off and enters F- cell
        
        Plasmid
        
        small circular DNA molecules that are separate from chromosomes
        
        found in bacteria and eukaryotic yeast
        
        can replicate independently of the rest of the cell
        
        are occasionally transferred between cells
        
        F plasmid
        
        cells with F plasmids function as DNA donors during conjugation
        
        Part 2: Conjugation and transfer of part of an Hfr bacterial chromosome, resulting in recombination
        
        Steps
        
        A single strand of the F factor breaks and begins to move through the bridge
        
        Crossing over can result in exchange of homologous genes
        
        An Hfr cell forms a mating bridge with an F- cell
        
        Enzymes degrade any DNA not incorporated. Recipient cell is now a recombinant F- cell.
      - Transformation
        
        the alteration of a bacterial cell’s genotype by the uptake of naked, foreign DNA from the surrounding environment
      - Transduction
        
        a type of horizontal gene transfer that occurs when a phage carries bacterial genes from one host cell to another, as a result of aberrations in the phage reproductive cycle
        
        Steps
        
        Fragment of bacterial DNA with A+ allele is packaged within a phage capsid
        
        Phage with A+ allele infects bacterial recipient cell
        
        Phage DNA is replicated and phage proteins are synthesized
        
        Incorporation of phage DNA creates recombinant cell with genotype A+ B-
        
        Phage infects bacterial donor cell that carries the A+ and B+ alleles
    - - When a prokaryote reproduces by binary fission, some of the offspring differ slightly in genetic makeup due to mutation
    - - binary fission
        
        cell division or mitosis