Exam 3 – Microbiology Answers – Flashcards
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| Nitrogen Fixation |
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| reduced N2->NH4 using H2 as the electron donor and ATP as the energy source. |
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| Nitrogenase |
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| catalyzing agent of nitrogen fixation (can be inhibited by O2) |
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| Aminations |
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| important for bacteria to produce different amino acids (biosynthetic) |
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| Transaminations |
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| moving an amino group from on compound to another |
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| Beta Lactams |
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| act as competitive inhibitors (bind to the active site) e.g. Penicillins |
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| Cephalosporins |
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| products of fungus (ceftazidime, cefotaxim) |
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| Beta lactamases |
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| plasmid encoded enzymes that cleave the lactam ring |
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| quinolone resistance |
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| altered gyrase |
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| Streptomycin resistance |
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| altered 16S rRNA |
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| beta lactam resistance |
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| altered penicillin binding proteins |
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| Co-administer |
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| drugs which would inhibit resistance factor. |
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| Resistant Pseudomonas |
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| exhibit reduced uptake of aminglycosides, beta lactams and quinolones. |
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| Rifampin |
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| inhibit or disrupt transcription |
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| aminoglycosides, tetracyclines, macrolides. |
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| inhibit or disrupt translation |
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| quinolones, mitomycin |
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| inhibit or disrupt DNA replication |
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| beta-lactams, bacitracin, vancomycin, cyclosporine |
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| inhibit or disrupt peptidoglycan synthesis |
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| cyclosporin |
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| reduces the activity of the immune system by interfering with the activity and growth of T cells. (used in transplants) |
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| Bacitracin |
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| inactivates bactoprenol by inhibiting removal of the extra phosphate in cell wall synthesis |
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| Vancomycin |
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| prevents transpeptidization of peptidoglycan subunits. |
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| Vancomycin resistance |
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| occurs when the terminal D-alanine is changed to either D-lactate or a D-serine residue preventing it from binding to the peptide chain. |
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| purines |
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| doube ring structure. |
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| pyrimidines |
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| (Uracil, Thymine, Cytosine) |
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| ribose |
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| 5 carbone sugar |
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| Deoxyribose |
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| 6 carbon sugar |
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| Complimentary |
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| bases in one strand match up with those of the other according to specific binding rules. A-T C-G |
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| Major groove |
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| large groove allowing transcription factors to bind to. |
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| G-C bond |
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| held together by 3 hydrogen bonds. (more stable) |
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| A-T bond |
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| held together by 2 hydrogen bonds. |
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| Melting Temperature Tm |
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| temperature at which a molecule of dsDNA separates into single strands. (dependent of length of bp and GC content) |
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| Nucleosides |
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| base and a sugar |
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| Nucleotides |
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| base, sugar, and a phosphate |
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| Sulfonamides |
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| inhibit folic acid synthesis by competitive inhibition (PABA analogues) |
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| Methotrexate/Trimethoprim |
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| competitively inhibit dihydrofolate (DHF) reductase because they are folic acid analogues, thus preventing the reduction of DHF |
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| DNA bases |
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| hydrophobic, helping to stabilize molecule. |
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| DNA sugar backbone |
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| Hydrophillic, linked by phosphodiester bonds that link the nucleotides within a strand. |
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| Bacterial DNA |
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| no compartmentalization of the cell allowing it to supercoil. |
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| DNA Pol I |
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| Cellular role is to repair. chain elongation 5->3 (polymerization) 3->5 exonuclease (proofreading) 5->3 exonuclease (RNA primer removal, nick translation) |
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| DNA Pol II |
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| chain elongation 5->3 (polymerization) 3->5 exonuclease (proofreading) |
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| DNA Pol III |
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| Heteromulteric protein. functions as a dimer. Chain elongation 5->3 (polymerization) 3->5 exonuclease (proofreading) |
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| Taq polymerase |
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| comes from Thermus aquaticus, used in laboratory polymerase chain reaction (PCR) |
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| Topoisomerase |
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| relieve tension generated by the rapid unwinding of the double helix. (actually breaks the strand) |
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| Single stranded DNA binding proteins |
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| protects ssDNA from nuclease activity, prevents ssDNA from re-anneling, straightens ssDNA preventing formation of secondary structure. |
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| Topoisomerase Type I |
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| single nicks DNA, unwinds DNA by revolving cut strand around axis of intact strand, nick closing activity, relaxes supercoils. |
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| Topoisomerase Type II |
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| ATP dependent, double nicks DNA. introduces negative supercoils, induces supercoiling (Gyrase) |
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| Replicon |
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| a unit of DNA replication, which consists of an origin of replication, region of replication, and a site of termination. |
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| Go Fuck Yourself |
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| I hate micro |
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| Replisome |
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| huge complex of proteins that includes DNA polymerase III holoenzyme |
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| Helicase |
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| responsible for separating the DNA strands, these enzymes use energy from ATP hydrolysis to unwind short stretches of helix just ahead of the replication forks. |
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| Primase |
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| enzyme that synthesizes a short RNA strand on the lagging strand, usually 10 nucleotides long and complimentary of DNA. |
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| Beta clamp |
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| tethers a DNA template to each core enzyme |
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| deoxyadenosine methylase |
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| methylation site GATC (DAM) |
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| Termination |
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| gene products of Tus binds to the Ter sites preventing progress of helicase. |
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| SeqA |
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| binds to DNA at dnaA box shortly after replication, binds DNA to inner plasma membrane, inhibits DAM activity, blocks dnaA expression; inhibits replication initiation. |
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| Intercalating agents |
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| flat planar molecules wedge in between stacked base pairs, prevent dsDNA melting. (bromide, actinomycin D, acridine orange) |
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| Quinolones |
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| inhibit nick closing activity of topoisomerases. (nalidixic acid, ciprofloxacin, fluoroquinolone. |
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| Novobiocin |
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| produced by streptomycin, inhibits supercoiling activity of topoisomerases, effective against S. aureus and other gram positives. (differentiating antibiotic) |
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| Proofreading |
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| the removal of a mismatched base immediately after it has been added. removal must occur before the next base is incorporated. |
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| mixed acid fermentation |
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| bacteria that can metabolize pyruvate to numerous products ethanol, and a mixture of acids, particularly acetic, lactic, succinct, and formic acids. |
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| Heterolactic |
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| form substantial amounts of products other than lactate, many also produce ethanol and CO2. |
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| Chloramphenicol |
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| binds to 50S subunit, inhibits transpeptidase activity. (broad spectrum) produced by streptomyces |
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| Kirromycin |
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| binds to EF-Tu, inhibiting its function |
