Block One Lecture 11

  1. In bacteria, __ is rare. 

    Explain tertiary and secondary.
    quaternary structure

    tertiary: secondary layer of folding--> more 3D--> 4 bonds (H bonds, ionic, S-S)

    secondary: hydrogen bond dependent
  2. Ionic bonds?

    Disulfide bonds?
    ionic bonds: opposite charges create a weak electrostatic bond

    S-S: only form with amino with sulfonated side chains
  3. Quaternary structure:
    interaction of peptide subunits. Must ahve primary, secondary, and tertiary to get the quaternary structure. 

    Subunits must be folded correctly 

    not many structural features that enable quaternary structure
  4. Mutation
    • 10^9 times more frequent than in eukaryotes
    • --> transformative mutations, nonsense, point, etc. (any change)
  5. Mutagens?
    UV light--> thymine dimers

    can be extracellular genetic material
  6. Spontaneous mutation
    mutation that arises apart from any mutagens

     most result in bacterium dying because the mutation would have messed with an important gene
  7. Nonsense codon:
    a misplaced stop codon (causes a shortened protein)
  8. Frameshift mutation
    • bases added or lost from genetic material
    • --> at point of change, every codon after that point is obliterated--> stop codon is no longer there--> protein goes on and on until it happen upon a codon
  9. Ionizing radiation
    humans use excision repair to fix int

    - if change is greater than 5, the cell breaks apart and dies

    • - ionizing nicks
    • - can't hold genome into 3D structure

    Once excision nicks occur, the cell dies because it can't hold the genome into 3D structure
  10. Why is bacteria mutation rate high?
    because they don't have good repair systems
  11. What is vertical gene transfer?
    new cells have slightl different genetic makeup than parent cell
  12. Horizontal gene transfer
    can acquire things from nature; they can hand off things
  13. ___ is turned to a single strand from a double strand.
    exogkenous DNA
  14. RecA: explain
    protein essential for the repair and maintenance of DNA

    strand goes off chromosome and new strand goes on
  15. Gram positive cells do what? 

    You need a __ (overgrown culture) to have the bacteria come in contact with __.
    release competence factors, which are secreted by cells. 

    critical mass

    competence factors
  16. What does ComD kinase do?
    tells cell CF is low-> activates series of genes to be expressed--> transformasome--> interacts with bacterial DNA that's outside cell, stabiliizes it to have it go inside cell
  17. What happens once inside cell?
    • it is linearized and turned into a single strand
    •  (after its in, its broken down)

    Once inside, recA proteins go to work. It's added to primary genome in pieces
  18. Some gram negative bacteria can try toform __. Why is it not possible?

    they have to go throguh the inner membrane, membrane, cell wal, periplasmic space. It's too complicated. Therefore, they do something else
  19. So, what do gram negative do?
    use pilus to randomly get DNA, uptake it, detect three and five prime ends
  20. Conjugation
    two cells get together, mostly gram negative. 

  21. Explain conjugation
    the pilus attaches, F+ factor is replicated and the cell begins to copy the materia
  22. Sometiems, in newly transformed cells, the __ integrates into the bacterial chromosome.
    F factor
  23. Sometimes, the F factor is successful in transforming __ cells; sometimes, regular DNA gets transmitted.
    F- cells
  24. Transduction
    very commonly in gram negative
  25. Explain transduction
    bacteriophage infects bacterial cell

    virus is the vector

    if bacteriophage carries bacterial DNA as opposed to viral DNA, it will form
  26. What does methylase do?
    preserves and modifies endonuclease
  27. Cut sites for type two are __
Card Set
Block One Lecture 11
Test One