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Prokaryotic Cells (Classification and Structure (Prokaryotic cell…

- - - - D: single cell organism similar in structure to bacteria
      - D: contain genes and metabolic pathway that makes it more similar to eukaryotes
      - Historically known as extremophiles - does not exist in extreme condition - recent research has shifted that perspective
      - Use alternative source of energy
        
        some are photosynthetic, others are chemosynthetic and can generate energy from inorganic compounds such as sulfur and nitroged based components such as ammonia
      - Hypothesized they have the same origin as eurokarytes, they both start with translation with methionine, contain RNA polymerases and associate DNA with histones
      - Archaea contains a single circular choromosome, divide by by binary fission or budding, and overall share a similar structure to bacteria
      - Resistant to many antibiotics
    - - contain cell membrane and cytoplasm, some have flagella or fimbriae (similar to cilia)
      - bacteria and eurokaryates have similar structure - so it is difficult to develop medicine that targets only one
      - there are enough biochemical difference that antibacterial vaccines can be developed to target bacteria
      - antibiotic aim for the bacterial ribosome which is significantly smmaler than the eukaryotic ribosome
      - More bacteria than animals and plants combined
      - Mutualistic symbiotics - co-exist with cells and good for us
      - Pathogens or parasites - provide no advantage and are harmful - ex. Chlamydia trachomatis - sexually transmited infection or clostirdium tentani - cause tetanus
  - - - require oxygen for metabolism
    - - Obligate
        
        cannot survice in an environment that does not have any oxygen
      - Aerotolerant
        
        unable to use oxygen but do not die when oxygen is present
      - Facultative
        
        using oxygen when present but switching when it is not present
      - Does not use oxygen - use fermentation or other forms of cellular metabolism
  - - - Cell wall is the outer barrier to the cell, cell membrane (plasma membrane) is the next layer and composed of phospholipids - together they are called envelope
      - F: provide structure
      - F: control the movement of solutes in and out of the baterium
      - Two types of cell wall
        
        Gram positive
        
        D: thick layer of peptidoglycan (polymeric substance made from amino acids and sugars)
        
        F: cell wall provides structure and may aid a pathogen by providing protection from a host organism's immune system
        
        Cell wall also contains lipteichoic acid - the human immane system might be activated by exposure to this
        
        Gram negative
        
        D.Thin walls, contain peptodoglycan bu in very low doses
        
        adjacent to cell membranne and separated by periplasmic space
        
        they also have outer membrane - contains phospholipids and lipopolysacccarides (this trigers an immure response in human beings)
        
        The inflammatory response to lipopolysaccharides is much stronger thant the response to lipoteichoic acid
        
        Detection method - stain using crystal violet stain and counter stain with safranin
        
        if the envolope absorbs the crystal violet stain - gram positive
        
        if it does not absorb the stain - then pink-red - gram neg
    - - D: whiplike structures used for propulsion
      - F: to move toward food or away from toxins or immune cells
      - Chemotaxis - ability of the cell to detec chemical stiumli and move toward or away from them
      - Structure
        
        Filament
        
        hollow, helical structure composed of flagellin
        
        basal body
        
        complex structure that anchors the flagellum to the cytoplasmic membrane, motor of flagellum, rotates upto 300Hz
        
        Hook
        
        contains the filament and the basal body - as basal body rotate, it exerts torque on the filament, which creates spin and propel bacterium forward
      - overall structure similar in gram positive and negative - some different physical structure and chem composition
    - - Some of the DNA in prokaryotic cel is carried on plasmids - can make it more resistant to antibiotics
      - do not have mitochondria - ATP production is done in the cell membrane
      - have a mild version of cytoskeleton
      - Contain ribosomes but they are different size from the eukaryotes - pro ribo- 30S to 50S subunits, vs. euk ribo - 40S to 60S subunits
- - - - Foreign genetic material integrates to host genomes - they come from bacteria after lysing
    - - The mating for bacteria - the donor male with pilus transfers genetic material to recipient femalel. The female becomes a male. The conjugation bridge is formed using the pilus.
    - - When a vector (virus that is carrying genetic material) is used to transfer gene from one bacterium to other one
    - - Genetic elements capable of inserting and removing themselves from the genome