Antibiotics

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Antibiotics
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Ampicillin and Kanamycin
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Ampicillin
-Inihibits cell wall synthesis
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(No Transcript)
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-Irreversible inhibits transpeptidase, which
cross-links the peptidoglycan
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Ampicillin Resistance
-beta-lactam antibiotic -Acquires a gene that
encodes ß-lactamase -Cleaves ß-lactam ring of
ampicillin -Ampicillin is no longer bound to
transpeptidase and therefore functions normally
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Kanamycin
-an aminoglycoside (amino modified sugar)
bacteriocidal antibiotic -Isolated from
Streptomyces kanamyceticus -Binds to the 30S
procaryotic ribosome
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Kanamycin
-Binds to the 30S procaryotic ribosome
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Kanamycin Resistance
-aminoglycoside modifying enzymes,
phosphorylation, making Kanamycin uneffective
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Bacteriostat vs. Bacteriocide
Ampicillin inhibits new cell wall
synthesis Kanamycin inhibits protein
synthesis
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Restriction Endonucleases
Nuclease Enzymes that digest or cut DNA and
RNA Endonuclease vs. Exonuclease Endonuclease
Cut nucleic acids at sites internal to the
molecule Exonuclease - Cut nucleic acids at
sites external to the molecule
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DNA Properties
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Restriction Endonuclease
-1950s, a primitive immune system in E. coli in
defense of bacteriophage lambda infection -1968,
Restriction enzyme HindIII was isolated from
Haemophilus influenzae -Recognition site for
HindIII 5 G T A C 3 3 C A T G 5
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Restriction Endonuclease
-1978, Nobel prize awards for the discovery of
restriction endonucleases and their application
to molecular genetics -Currently over 3000
restriction endonulceases isolated with 230
recognition sequences -Mostly isolated from
bacteria, but some from viruses, archaea, and
eucaryotes
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HindII
-Recognition site for HindIII 5 A A G C T
T 3 3 T T C G A A 5 -Cleavage
Products 5 A A G C
T T 3 3 T T C G A
A 5
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Lambda (?) Phage
-Bacteriophage with double-stranded DNA genome,
48,502 bp
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DNA Gel Electrophoresis
-Separation of DNA fragments through agarose by
application of an electric field
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DNA Gel Electrophoresis
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DNA Gel Electrophoresis
-DNA Mobility is inversely proportional to Log10
of its Molecular Weight