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Chapter 27 - Coggle Diagram

- - - - Obligate aerobes require O2 for cellular respiration
      - –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 not
      - nitrogen fixation
        
        prokaryotes convert atmospheric nitrogen (N2) to ammonia (NH3)
        
        Nitrogen-fixation is isolated in cells called heterocysts
        
        Cells of one or more prokaryote species cooperate to form surface-coating colonies called biofilms
        
        Spirochetes
        
        •These bacteria are helical gram-negative heterotrophs that spiral through the environment by rotating internal filaments
        
        Methanogens are obligate anaerobes that produce methane as a by-product of their metabolism
        
        decomposers, they break down dead organisms and wastes and release carbon and other elements
        
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- - - - a network of sugar polymers cross-linked by polypeptides
      - Gram stain to classify bacteria by cell wall composition
        
        Gram-positive bacteria have simpler walls with a large amount of peptidoglycan
        
        gram-negative bacteria have less peptidoglycan and are more complex with an outer membrane that contains lipopolysaccharides
        
        capsule
        
        dense and well-defined, or a slime layer if it is not well organized
        
        In mutualism, both symbiotic organisms benefit
        
        •In commensalism, one organism benefits while neither harming nor helping the other
        
        •In parasitism, an organism called a parasite harms but does not usually kill its host
        
        •Parasites that cause disease are called pathogens
- - - - taxis, the ability to move toward or away from a stimulus
        
        Prokaryotes lack a nucleus; the chromosome is in the nucleoid,
        
        Prokaryotes may also have smaller rings of independently replicating DNA called plasmiDs
        
        Exotoxins are proteins secreted by bacteria that can cause disease even if the bacteria are no longer present
        
        Endotoxins are lipopolysaccharide components of the outer membrane of gram-negative bacteria
        
        CRISPR-Cas9 system, which helps prokaryotes defend against viral attack, has been developed as a gene altering tool
        
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- - - - –Rapid reproduction
      - Mutation
      - Recombination
      - transformation,
        
        prokaryotic cells incorporate foreign DNA taken up from their surroundings
        
        transduction
        
        phages (from “bacteriophages,” viruses that infect bacteria) carry prokaryotic genes from one host cell to another
        
        Conjugation
        
        the process through which DNA is transferred between two prokaryotic cells
        
        F factor (F for fertility) is required for the production of pili
        
        F plasmid (F+ cells) function as DNA donors
        
        R plasmids, plasmids that carry resistance genes
        
        Extremophiles are archaea that live in extreme environments, uninhabitable for most organisms
        
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