Unit 2 Study Guide (1).docx

**UNIT 2 -- Study Guide** [Chapter 7 -- Microbial Nutrition, Ecology, and Growth] Nutritional types \- phototrophs vs. chemotrophs \- autotrophs vs. heterotrophs Transport processes 1\. Passive: simple diffusion, facilitated diffusion, osmosis (hypertonic, hypotonic, isotonic) 2\. Active: pri...

**UNIT 2 -- Study Guide** [Chapter 7 -- Microbial Nutrition, Ecology, and Growth] Nutritional types \- phototrophs vs. chemotrophs \- autotrophs vs. heterotrophs Transport processes 1\. Passive: simple diffusion, facilitated diffusion, osmosis (hypertonic, hypotonic, isotonic) 2\. Active: primary, secondary, group translocation 3\. Bulk transport: endocytosis, exocytosis Environmental factors 1\. Temperature (psychrotroph, mesophile) 2\. pH (acidophile, neutrophile, alknalinophile) 3\. Osmotic pressure: (halophile, obligate halophile, facultative halophile) 4\. Oxygen: obligate aerobe, obligate anaerobe, microaerophile, aerotolerant anaerobe, facultative anaerobe) Microbial growth \- binary fission (2^n^, where n = \# of generations) \- growth curve phases: lag, exponential growth (log), stationary, death \- generation time (growth time in minutes / \# of generations) [Chapter 8 -- An Introduction to Microbial Metabolism] Metabolism 1\. Anabolism: endergonic, condensation/dehydration reactions 2\. Catabolism: exergonic, hydrolytic/degradation reactions Enzymes \- characteristics \- lower activation energy, increase reaction rate \- simple enzyme vs. holoenzyme \- cofactors: metal ion, coenzyme \- active site Factors that influence enzyme activity 1\. Temperature 2\. pH 3\. Substrate concentration 4\. Inhibitors and activators \- competitive, noncompetitive, and allosteric inhibitors/activators \- feedback inhibition Cell energetics \- endergonic and exergonic reactions \- central role of ATP Oxidation and reduction \- OIL RIG \- electron carriers (NAD+/NADH, FAD/FADH~2~) Pathways of bioenergetics 1\. Aerobic respiration: glycolysis, pyruvate oxidation, Krebs cycle, ETC and AS final e- acceptor is O~2~ ATP yield: 38 per glucose glycolysis summary: glucose → 2 pyruvate + 2 ATP + 2 NADH pyruvate oxidation summary: 2 pyruvate → 2 acetyl-CoA + 2 NADH Krebs cycle summary: 2 acetyl-CoA → 2 ATP + 6 NADH + 2 FADH~2~ ETC: series of redox reactions and H+ pumping into intermembrane or periplasmic space ATP synthase: H+ gradient is used to make ATP overall summary: glucose + 6 O~2~ + 38 ADP + 38 Pi → CO~2~ + 6 H2O + 38 ATP 2\. Anaerobic respiration: glycolysis, pyruvate oxidation, Krebs cycle, ETC and AS final e- acceptor is not O~2~ ATP yield: varies per glucose 3\. Fermentation: glycolysis lactic acid, ethanol, or other gas or acid end-product ATP yield: 2 per glucose [Chapter 9 -- An Introduction to Microbial Genetics] Genomes \- prokaryote, eukaryote, virus DNA vs. RNA \- nucleic acid structure \- sugar (ribose, deoxyribose) \- N-containing base (adenine, guanine, cytosine, thymine, uracil) \- phosphate(s) \- nucleotide vs. nucleoside DNA structure \- characteristics The flow of genetic information \- DNA → RNA → protein \- gene (via transcription) → mRNA (via translation) → protein DNA replication \- characteristics \- conservative, semiconservative, and dispersive models \- DNA polymerase Transcription \- gene \- characteristics \- RNA polymerase Translation \- ribosomes \- codons (sense vs. nonsense) \- involves mRNA, tRNA, and rRNA \- genetic code Operons \- promoter, operator, structural genes 1\. *lac* operon \- inducible \- Glc present, Lac absent: repressor bound to operator → no transcription \- Glc absent, Lac present: AlloLac (inducer) bound to repressor → transcription \- *lacZ* → beta-galactosidase (2 functions) \- *lacY* → permease \- *lacA* → transacetylase 2\. *trp* operon \- repressible \- Trp absent: inactive repressor → transcription \- Trp present: Trp (corepressor) bound to repressor → no transcription Mutations 1\. Substitution (point): silent, missense, nonsense 2\. Frameshift: insertion, deletion Horizontal gene transfer \- characteristics 1\. Conjugation: physical contact via sex pilus \- F+ x F- mating → F+ stays F+; F- becomes F+ \- Hfr x F- mating → Hfr stays Hfr; F- stays F-, gene recombination may occur 2\. Transformation: uptake of "naked" DNA \- R and S strains of *S. pneumoniae* \- gene recombination may occur 3\. Transduction: via bacteriophage \- gene recombination may occur [Chapter 11 -- Physical and Chemical Agents for Microbial Control] Decontamination 1\. Inanimate objects (fomites): sanitization, disinfection, sterilization 2\. Living tissue: degermation, asepsis Relative susceptibilities of microbes to antimicrobial agents \- prions, endospores, naked viruses, "hardy" vegetative bacteria, enveloped viruses, vegetative bacteria Factors that influence the killing rate by antimicrobial agents 1\. length of exposure 2\. \# of microbes/microbial load 3\. nature of microbes 4\. mode of action (microbicidal or microbistatic?) 5\. concentration of agent 6\. temperature of environment 7\. presence of interfering material (ex: blood, mucus, feces) Heat 1\. Moist heat: pasteurization, boiling water, autoclave 2\. Dry heat: dry oven, incineration Radiation 1\. Ionizing: X-rays and gamma rays penetrate cells, cause loss of e-, sterilize 2\. Non-ionizing: UV rays penetrate cells, cause DNA distortion, disinfect Chemicals Antimicrobial agent targets 1\. Cell wall 2\. Plasma membrane 3\. Nucleic acid synthesis 4\. Protein synthesis 5\. Protein function [Chapter 12 -- Drugs, Microbes, Host: Elements of Chemotherapy] Characteristics of the ideal antimicrobial drug Terms: chemotherapy, antimicrobial drug, antibiotic (natural, synthetic, semisynthetic), narrow Major drug targets 1\. Cell wall 2\. Plasma membrane 3\. Nucleic acids 4\. Ribosome 5\. Metabolic pathways Major antibacterial drugs 1\. Cell wall synthesis A. Penicillins B. Miscellaneous 2\. Plasma membrane A. Polypeptides 3\. Nucleic acids A. Fluroquinolones B. Rifamycins 4\. Protein synthesis A. Aminoglycosides B. Tetracyclines C. Macrolides 5\. Folic acid synthesis A. Sulfamethoxazole B. Trimethoprim Acquisition of drug resistance 1\. Gene transfer \- conjugation \- transformation \- transduction 2\. Gene mutations \- drug inactivation \- decreased permeability \- activation of drug pumps \- change in drug binding siter \- use of alternative metabolic pathway Interactions between drug and host 1\. Organ toxicity 2\. Allergic responses 3\. Alteration of microbiota The process of selecting an antimicrobial drug 1\. Identifying the microbe 2\. Testing for the drug susceptibility of microbes 3\. Patient factors