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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
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Ionic bonds?
Disulfide bonds?
ionic bonds: opposite charges create a weak electrostatic bond
S-S: only form with amino with sulfonated side chains
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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
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Mutation
- 10^9 times more frequent than in eukaryotes
- --> transformative mutations, nonsense, point, etc. (any change)
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Mutagens?
UV light--> thymine dimers
can be extracellular genetic material
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Spontaneous mutation
mutation that arises apart from any mutagens
most result in bacterium dying because the mutation would have messed with an important gene
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Nonsense codon:
a misplaced stop codon (causes a shortened protein)
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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
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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
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Why is bacteria mutation rate high?
because they don't have good repair systems
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What is vertical gene transfer?
new cells have slightl different genetic makeup than parent cell
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Horizontal gene transfer
can acquire things from nature; they can hand off things
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___ is turned to a single strand from a double strand.
exogkenous DNA
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RecA: explain
protein essential for the repair and maintenance of DNA
strand goes off chromosome and new strand goes on
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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
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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
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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
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Some gram negative bacteria can try toform __. Why is it not possible?
transformasomes
they have to go throguh the inner membrane, membrane, cell wal, periplasmic space. It's too complicated. Therefore, they do something else
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So, what do gram negative do?
use pilus to randomly get DNA, uptake it, detect three and five prime ends
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Conjugation
two cells get together, mostly gram negative.
Specific
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Explain conjugation
the pilus attaches, F+ factor is replicated and the cell begins to copy the materia
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Sometiems, in newly transformed cells, the __ integrates into the bacterial chromosome.
F factor
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Sometimes, the F factor is successful in transforming __ cells; sometimes, regular DNA gets transmitted.
F- cells
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Transduction
very commonly in gram negative
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Explain transduction
bacteriophage infects bacterial cell
virus is the vector
if bacteriophage carries bacterial DNA as opposed to viral DNA, it will form
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What does methylase do?
preserves and modifies endonuclease
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Cut sites for type two are __
palindromes
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