Eukaryotes and Viruses

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Eukaryotes and Viruses
2013-11-27 15:20:04
Topics cumulative Final Exam
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  1. what is the peptidoglycan structure And how do you insert a monomer?
    • -composed of sugars and proteins
    • -composed of NAM and NAG with 5 amino acids linked to the NAM sugar
    • - Autolysins cut the cell wall, transglycosidase link the sugars, transpeptidase crosslink the peptide side chains
  2. Describe Gram positive Cell wall
    • -thick layer of peptidoglyan consisting of sheets with interconnected glycan chains crosslinked via tetrapeptide chains
    • -teichoic acid/lipoteichoic acid-stick out above the peptidoglycan.
    • -various sugars like D-alanine are attached.
    • -some are covalently joined to the peptidoglycan molecule (wall teichoic acids, linked to NAM) in which these help stabilize the gram positive cell wall.
    • -the ones linked to the cytoplasmic membrane is the lipoteichoic acid
    • -gves the cell its negative charge
  3. Describe Gram negative cell wall
    • -contains a thin layer of peptidoglycan
    • -outside is the outer membrane (bilayer embedded with proteins and joined to the peptidoglycan by lipoproteins)
    • -embedded with porin proteins which allows molecules in periplasmic space
    • -lipoprotein link plasma membrane and outer membrane to the periplasma's peptidoglycan
    • -Lipopolysaccharide (LPS): also known as endotoxin.
    • -Lipid A is found in most Gram negatives. the core polysaccharide is conserved in specific genus or species, and the O side chain is variable within species
    • -periplasma is the space between the plasma membrane and the outer membrane
    • -contains peptidoglycan and enzymes
    • -peptidoglycan side-chains are directly linked, there is no interbridge
  4. Describe chemotaxis
    • directed movement of bacteria in response to chemical stimuli in the environment
    • -flagellum is responsible for motility
    • -movement is not a straight line
    • -change of rotation of the flagellum causes the cell to tumble
    • -cells tumble less frequently when they are closer to attractant and when they are moving away from a repellent resulting in longer runs
  5. Describe what Ribosomes are