Exam 1

What did Edward Jenner contribute to microbiology?

-Developed the 1st vaccine for small pox using the pustules from cattle as inoculum (observed cause and effect before microbes and disease had been linked)

What did Louis Pasteur contribute to microbio?

-Coined aerobic and anaerobic to describe alcohol production in yeast
-Found a method to pasteurize milk and wine (boiled broth in swan neck flask exposed to air)
-Ended debate on spontaneous gen
-Used attenuated strain to vaccinate chicken cholera

What was Robert Koch's contribution to microbiology?

-Validated germ theory by publishing a paper on anthrax that shows direct correlation between it & disease
-Made pure cultures possible (gelatin, agar)
-Discovered the cause of TB and cholera

What are Koch's postulates?

1. Microbe found in diseased, but NOT in healthy
2. Microbe isolated from diseased & grown in pure culture
3. Microbe introduced into healthy, causes disease
4. Same strain of microbe found in newly diseased

What did Fredrick Griffith contribute to microbiology?

-Discovered transformation in bacteria
1 Injected live strain S into mice - killed
2 Injected live strain R into mice - lived
3 Injected dead strain S into mice - lived
4 Injected dead strain S & live strain R - died

What did the experiment by Oswold Avery, Macleod & Macarthy demonstrate?

-Showed the microbes used in Griffith's experiment were heat sensitive @ 80 degrees, protease resistant, RNAse resistant, but NOT DNAse resistant (i.e. showed that DNA was the mode of genetic transformation)

What did the Hershey-Chase experiment demonstrate?

-Demonstrated that DNA is the mode of genetic transformation

What was Alexander Flemming's contribution to microbiology?

-He wrote a paper describing the effects of penicillin on gram-positive bacteria
-He didn't repeat the experiment and went on to other things (didn't realize the implications)

What did Howard Florey and Ernest Chain contribute to microbiology?

-Took Flemming's culture (of penicillin) and extracted the antibiotic
-Proved it could cure infections in animals

What was the contribution of Walter Gilbert and Fred Sanger to biology?

-Independently developed methods to determine the exact sequence of DNA

What was Stanley Prusiner's discovery?

-Finds evidence that a class of infections proteins called prions cause scrapie

What was Kary Mullis's discovery?

-Used the heat stable enzyme from Thermus aquaticus to establish PCR reaction technology

What is the "model system" as it applies to microbiology?

-When studying a certain process, it is beneficial for scientists to look at one organism to understand the basic process
-Once the process is understood, a wider scope can be taken

What is one example of a model system that was used to discover a process?

-Scientists looked at E. coli when studying homologous proteins (found in most organisms) that respond to heat shock
-Found 3 types of proteins: regulators, chaperones, and proteases

About how old is the earth?

5 billion years

What is the prebiotic soup model of early life?

-Organic building blocks of life could arise abiotically out of simple reduced chemicals (e.g. ammonia)
-Could've generated complex macromolecules that eventually acquired the apparatus needed for self-replication & membrane compartmentalization

What is the metabolist model of early life?

-Central components of metabolism, including TCA cycle to generate AAs, arose from self-sustaining chemical rxns based on inorganic chemicals
-These abiotic rxns then acquired self-replicating macromolecules and membranes

What is the RNA world hypothesis?

-Model of early life in which RNA performed all the information & catalytic roles of today's DNA & proteins

What two facts support the RNA world hypothesis?

1. RNA, like DNA, can store information
2. RNA can duplicate itself or other molecules

What was the first microbe grown in pure culture and by whom?

-Bacillus anthracis (anthrax), by Robert Koch

What are some characteristics of myxobacteria?

-Predatory microbes that hunt in groups
-Go through a complex developmental cycle in which they form fruiting bodies

What are some main reasons microbes are difficult to classify?

-Small w/ few morphological features
-Metabolic activities can change frequently
-Haven't been or are unable to be cultured

What was the contribution of Ernest Haeckel?

-Attempted to classify microbes into one "catch-all" category = protists
-The other categories were animals and plants

What are the 5 kingdoms in the "5 Kingdom Classification" and who proposed it?

Proposed by: Robert Whittaker
Classified by: Method of nutrient acquisition & structure and complexity
-Animals
-Plants
-Fungi
-Protists
-Monera

What were two distinctions of metabolism that were used to classify microbes?

-Source of CO₂ (Heterotroph vs autotroph )
-Source of energy (photo vs chemo)

What is molecular phylogeny and what issue did it propose to solve?

-The classification of organisms based upon their evolutionary relationships and their descendence from a common ancestor is determined by comparing the sequences of common molecules

What are the properties of a genetic phylogeny marker?

The genes:
-Must be present in all organisms of interest
-Can't be subj to lateral transfer
-Must display appropriate level of sequence conservation for divergences of interest
-Must be large enough to contain a record of the historical info

What makes 16s rRNA a good genetic phylogeny marker?

-Present in all bacteria, archael, and eukaryotic cells
-Required for translation of mRNA into protein

What are characteristics of a rooted phylogeny tree?

-Reflect the most basal ancestor of the tree in question

What issues can a scientific determination of a phylogenetic tree face?

-Lateral gene transfer
-Genes acquired through environment, conjugation, or bacteriophages
-Defining a species and taxonomic relationships with multiple "parents"
-Up to 10% of a phylum can deviate from the "norm"

What is random mutation?

-DNA sequence changes through rare mistakes as the chromosome replicates
-Replication errors result in mutation most of which have no effect on gene function

What is natural selection?

-Favors organisms that produce great numbers of offspring in a specific environment

What are characteristics of encoding genes under selection pressure?

-Show mutation frequencies much lower or higher than the random mutation rate
-Do NOT serve as molecular clocks

What is reductive evolution?

-W/o selection for a trait, genes encoding the trait accumulate mutations w/o affecting the organisms' reproductive success. Mutations that ↓ function are more common than mutations that ↑ function, more mutations w/o selective pressure → lost trait

What is punctuated equilibrium?

-Proposes that stasis is broken by rare events of large change (e.g. flood); characterized by rapid events of branching speciation

What is phyletic gradualism?

-Species continue to adapt to new environmental and biological selection pressures over the course of their history, gradually becoming new species

What is a molecular clock?

-Temporal information contained in a macromolecular sequence (history of a species contained in DNA or protein)

What is DNA hybridization?

-Technique that measures the degree of genetic similarity between pools of DNA sequences

What was the "first living organism" called and what characterized it?

-Progenote (simple; maybe too simple to be called an organism)
-Carried out essential processes inefficiently (by current standards) but there was little competition which gave to high mutations rates and rapid evolution

What is neo-Lamarckism?

-The belief that stress or environmental conditions can induce specific mutations to overcome stress

What did the results Cairns experiment demonstrate about evolution?

-Originally thought that Lac-strains (which were challenged to use lactose to grow) demonstrated corrective mutation (in which stress induced specific mutation)
-Later proved that a leaky mutation was sufficient to produce a small microcolony

What did the Luria-Delbrook experiment demonstrate about evolution?

-Proved that mutations arose spontaneously, prior to plating in media (and disproved Cairns experiment because the same number of mutations did not show up on each plate as would be expected; was instead variable)

What defines coevolution?

-The evolution of two species in response to one another (showing parallel phylogeny)
-Often involves reductive evolution

Define symbiosis

-The living together of two kinds of organisms

Define syntrophy

-One organism uses the products from another organism

Describe endosymbiosis

-Most intimate kind of symbiosis
-Leads to reductive evolution (loss of genes)
-Includes microbes in human digestive tract

What characteristic of primitive eukaryotes provides evidence of coevolution?

-Lack mitochondria but evidence that they once had them (bacterial genes present in their nuclear DNA & contain remnants of membrane bound mitochondrial organelles)

What, supposedly, did mitochondria and chloroplasts evolve from?

-Mitochondria from captured Proteobacteria
-Chloroplasts from captured cyanobacteria

What two organelles in plants are endosymbionts?

-Mitochondria and plastids (type of chloroplast that contains ribosomes similar to bacteria and mitochondria w/ their own DNA that shares similarity w/ proteobacteria and cyanobacteria)

What endosymbiotic relationship evolved more recently than chloroplasts & mitochondria and is not capable of independent growth?

-Aphids have endosymbionts that produce essential amino acids

Concerning proteins, what is one possible function of introns?

-Facilitate recombination events (swapping of domains in proteins which can yield new functions)

What are orthologs?

-Genes in different species that evolved from a common ancestral gene by speciation (usually retain same function)

What are paralogs?

-Genes related by duplication within a genome (evolved new functions)

What is the cell wall of bacteria comprised of?

-Peptidoglycans

What characterizes a phylum?

-Group of organisms w/ a common ancestor
-Still diversity in metabolism and/or ecological niche or role

What is the most discriminatory method to determine commonality?

-Sequencing genes

What are some non-culture based techniques?

-Extract DNA from environment the organism is found in and use PCR to amplify the 16s rRNA

What are characteristics of all deep-branching thermophiles?

-Branched early on in evolution
-Rapid growth, high mutation (impacts molecular clock)
-Grow at high temperatures

What are characteristics of aquificales, thermotagales?

-Live in near-boiling water (can grow in modified "pressure-cooker")
-Share 25% of genome has archaeal origin

What are some characteristics of Deinococcus?

-lives at lower temps

-extremely radiation-resistant

-very rapid DNA repair

What are some characteristics of Chloroflexi?

-Green nonsulfur bacteria

-Filamentous phototrophs

-Live at high temps (microbial mats in yellowstone)

-many have chromosomes (contain photosynthetic apparatus)

-main filamentous phototrophs besides cyanobacteria

What are some functional characteristics of cyanobacteria?

-O2 production unique to this group and chloroplasts

-many fix N

-can photolyze hydrogen in absence of oxygen

-grow as filaments, single cells, endosymbionts or colonies

What is the purpose of the mucilage production in cyanobacteria?

-Prevent drying

-Exclude O2 (for N fixation by heterocysts and photolyzation of H)

What are some cellular structures of cyanobacteria?

-Thylakoids (separate from plasma membrane; photosynthetic apparatus; similar to chloroplasts)
-Carboxysomes (lipid bodies where CO2 fixation occurs)
-Gas vesicles (buoyancy to maintain position in water column)
-Heterocytes (N fixation; NO oxygen)

What are some general characteristics of gram positive firmicutes bacteria?

-Rods, cocci and mycoplasms included
-Some are spore formers
-No outer membrane (thick cell wall)
-Many are pathogens

What are some main characteristics of gram positive endospore producers & give examples?

-Extremely heat resistant for millenia
-Toxin formers (e.g. clostridium - tetnus & bacillus - anthrax)
-Spore forms inside mother cell

What are some general characteristics of gram negative proteobacteria?

-Largest group (5 major classes)
-Many light supplemented heterotrophs (purple light receptors; use of inorganic electron donors; highly adaptable metabolism)

What are the five classes of gram negative proteobacteria?

-Alpha, beta, gamma, delta, epsilon

What are the two types of gamma proteobacteria?

-Facultative anaerobic rods (grow w/ or w/o O2; many are motile; many pathogenic; e.g. E. coli, Salmonella, Shigella)
-Aerobic rods (need O2 to grow; some are pathogens; e.g. Pseudomonas, Legionella)

Describe and give two examples of bacteria of the class delta proteobacteria class.

-Contain the order "myxococcales" or myxobacteria
-Myxococcus xanthus (attacks other bacteria in "packs"; aggregates into fruiting bodies; disperses myxospores)
-Bdellovibrio bacteriovorus (parasitizes other bacteria; grows in periplasm; lyses host)

Describe and give one example of the class epsilon proteobacteria of the proteobacteria phylum.

-Smallest group of proteobacteria
-Commonly inhabit the human digestive tract
-e.g. Heliobactor pylori (cause of stomach ulcers; burrows below protective mucous layer into epithelial cell of the stomach

Describe the class Chlamydiae of the proteobacteria phylum.

-Obligate intracellular parasites (wall-less)
-Larger reticulate body (grows w/in cells; can't survive outside host cell)
-small elementary bodies (survive outside host cells; transferred to new host; similar function to a spore)

Describe the bacterial phylum planctmycetes.

-Cell wall-less oligotroph (survive low levels of nutrients)
-Multiple internal membranes
-Double membrane surrounds nucleoid (protein, nucleus, chromosomes; similar 2 eukaryotic nucleus)
-Budding like yeast
-Transcrpt & transltn not compartmentalized

Describe the bacterial phylum verrucomicrobia.

-Wrinkled microbes; oligotrophs
-16s rDNA amplifies poorly w/ standard primers
-Wart like projections contain tubulin (cytoskeletal protein of eukaryotes; horizontal gene transfer from eukaryotes?)

Why is the actual branch point of hyperthermophiles controversial?

-The molecular clock is disturbed

Describe some general traits of archea.

-Widest range of environments (temp, pH, pressure, anaerobic)
-Unique biochemistry (methane production; no peptidoglycan - pseudomurien; difference in glycolytic pathways)
-S-layers (unique envelope composed of protein)

Describe the lipid membrane of archea.

-L-glyceol not D-glycerol
-Ether links, not ester
-Branched chains of lipids (no unsaturations in lipids)
-Can be more exotic forms (macrcyclic diether; cyclopentane rings) could contribute to withstanding extreme conditions

What 4 chemical adaptations are used to stabilize proteins and archeal membranes to heat and low pH?

-Ion pairs/acidic and basic residues
-Disulfide bridges
-Hydrogen bonds
-Hydrophobic interactions

In what ways re archeal genomes similar to bacterial?

-Circular genome
-Has operons

In what ways are archeal genomes similar to eukaryotic?

-Has introns
-RNA polymerase has TBP, TFB
-Has proteins similar to histones (assist in packaging DNA)

Describe viridilantae.

-Contains algae and plants
-Have engulfed phototrophs (cyanobacteria)
-"cryptophyte algae" are protists (engulfed algae which engulfed cyanobacteria; still maintain DNA in vestigial nucleus)

Give examples of protists.

-Amoebas
-Alveolates (ciliated protists)
-heterokonts (different shaped flagella; e.g. diatoms, kelp)
-Euglenozoa (free-living flagellates)
-Excavates (lack mitochondria although genes remain; e.g. giardia)

What are characteristics of fungi?

-Cell walls contain chitin (strong polysacch)
-Cells can't extend pseudopods; must absorb food as individual molecules (can't ingest large particulates)
-Secrete growth material at hyphal tips (extend hyphae at tip)

Describe yeasts.

-Unicellular fungi
-Most reproduce via budding (leave bud scar site; mother cell ages, senesces, and dies)
-Some reproduce by binary fission
-Under stress, diploid cells can enter into sexual reproduction w/ spores

Describe common characteristics of algae.

-Chloroplasts
-Paired flagella
-Cell wall made of glycoprotein or cellulose
-Contractile vacuole removes excess water
-Pyrenoid concentrates CO2 for fixation
-Stores energy as starch

Describe common characteristics of amoebozoa.

-Protazoan
-Amorphous shape
-Lobe-shaped pseudopods (actin pushes cytoplasmic streams ahead; cell rolls over membrane) which engulf food
-Slime molds (feed, mate as individual cells; aggregate to form fruiting body signaled by cAMP)

Describe dinoflagellates of the superphylum aveolates.

-2 long flagella (one wrapped around cell groove)
-Secondary endosymbiont (possesses a red algal chloroplast)
-Extrosome secretes toxins (neurotoxins)
-Some are endosymbionts (essential for coral survival)
-Some are predators

How does a reaction become more favorable in a microbial environment?

-Community members eat the products of another member's reaction which shifts the equilibrium

What type of reaction are nearly all biological cycles comprised of?

-Redox

What part do anaerobic molecules play in the carbon cycle?

-Release methane into the atmosphere

What is the purpose of methanotrophs in the environment?

-Oxidize methane by anoxic (no oxygen) methane utilization (sulfur is used as e- acceptor)

What are the steps in fluorescent in situ hybridization of a culture?

-Determine necessary probe & produce it
-Extract cells from sample
-Chromosome attached to slide
-Probes and slides incubated for 12 hours
-Wash slides to remove unhibridized
-Look at hybridized under microscope

How do scientists identify microbes in consortium?

-Can't culture; so determine composition via molecular methods (16S rRNA-targeted probes)

What property makes dinitrogen stable?

-The triple bond which requires a lot of energy to break

What organisms are capable of breaking the dinitrogen triple bond?

-Only prokaryotes

What organisms are involved in nitrification and denitrification?

-Only prokaryotes

What are the steps of nitrification?

-Conversion of ammonium (NH₄⁺) to nitrite (NO₂^-)
-Conversion of nitrate to nitrate

What is the process of denitrification?

-Cascade of anaerobic respirations that convert nitrate ions (NO₃^-) to nitrogen gas (N₂)

What is the process of anammox?

-Anaerobic formation of nitrogen gas from ammonia nitrate
-Recently identified; missed because microbes responsible hard to culture

What are the two main ways nitrogen is used by organisms?

-All use it as a nutrient (assimilatory)
-Some prokaryotes use it s a substrate for ATP-generating processes (oxidaton of ammunium or nitrate; use as terminal e- acceptor in anaerobic conditions) - dissimilatory

What enzyme is responsible for N2 fixation (reduction of Nitrogen gas)?

-Nitrogenase

What happens during nitrogen fixation?

-Nitrogen gas (N2) is reduced to ammonium by nitrogen-fixing bacteria

What are two important constraints of nitrogenase?

-It has oxygen-sensitive cofactors (Fe-S) but actually uses O2 as an e- acceptor
-Requires a large amount of energy (16 ATP) to break the N2 bond; is very tightly regulated

What physical characteristics does nitrogenase possess?

-2 copies each of two proteins
-2 molybdoferredoxin and 2 azoferredoxin

What two metabolic roles does the sulfur cycle play in microbes?

-Assimilation as an essential nutrient
-Dissimilation -- enters oxidative and reductive pathways that generate ATP

What are some basic characteristics of the phosphorus cycle?

-Simplest cycle; remains in same oxidation state
-No gaseous intermediate
-Soluble, accumulates in oceans
-Phosphanates produced by eukaryotes and prokaryotes
-Some return of phosphate from ocean to land by animals

How do clouds form?

-When compounds in the air act as nuclei for water vapor to condense on; some compounds contain sulfur (abiotic sources such as volcanic emissions)
-Sulfur dioxide is oxidized to sulfate in atmosph. & hydrated to sulfuric acid which is acid rain

How can microbes positively affect the weather/climate?

- Phytoplankton produce DMSP to protect themselves from the sun's UV rays
-Bacteria metabolize DMSP to DMS which is volatile and taken up into the atmosphere where it forms more clouds = LESS SOLAR RADIATION

What can confocal microscopes accomplish (as far as microbiology is concerned)?

-Can examine through layers and search for specific members

What is a mutualistic symbiosis?

-Both partners benefit

What would a DNA array allows scientists to observe?

-Can monitor an entire community; can also do expression analysis

What are two pieces of evidence suggesting a symbiotic relationship that ultimately gave rise to chloroplasts and mitochondria?

-Chloroplasts DNA has homology w/ cyanobacteria
-Mitochondria DNA has homology w/ rickettsiea (a human intracellular parasite)
-Mit. & chlor. replicate by binary fission; some have proteins required for bact division
-Ribosomes resemble bacterial

What is the symbiotic relationship between legumes and rhizobium?

-Legumes secrete attractants
-Rhizobium expresses node genes
-Rhi enters cortical cells; differentiates into bacteriods (no cell wall)
-Rhi provides legumes w/ fixed (usable) nitrogen
-Legumes provide rhi w/ energy, reducing power & removes O₂

What function does arbuscular mycorrhizal fungi serve in symbiosis with higher plants?

-Improve their partner's ability to phosphate, nitrogen and water from the soil

What are some key roles of microbes in ruminants?

v-Sugars are fermented into VFAs; ruminants for carbon and other metabolic needs
-Amino acids obtained from dead microbes, lysozyme in abomasum (acid tolerant)
-Methanogens prevent hydrogen accumulation

What did the Hawaiian squid us the colonies of bacteria for?

-To illuminate the ocean floor while hunting @ night (avoid projection a shadow)

Describe the symbiotic relationship between the nematode and bacteria.

-The nematode reproduces inside caterpillars of insects and needs the bacteria to produce a toxic substance that kills the caterpillars by inducing apoptosis of the gut wall

How do microbes obtain energy from deep sea ocean vents?

-Primary producer is a microbe that oxidizes H₂S to generate energy

What substance causes the white plume of the "white smokers" deep sea vents?

-Sulfur precipitant

What is the main difference between the white and black "smoker" deep sea vents?

-Black smoker vents are very hot (350-400 degrees C)

What are 4 types of metabolism in deep sea vents?

-Methanotrophs
-Methylotrophs
-Hydrogen oxidizers
-Sulfide oxidizers

What is the symbiotic partnership between tubeworms and microbes?

-Worm delivers CO2 and H2S to symbiont using hemoglobin-like protein
-Bacterial symbiont oxidizes methane and H2S for metabolism
-Symbiont provides organic matter for worm

What is the symbiotic partnership between termites and microbes?

-Termites eat wood & soil
-Microbes live in termite gut & digest cellulose
-Hydrogen produced by the gut microbes is used by methanogens (methane to atmosphere) and by acetogens (acetate back to termites)

In what way is myxobacteria predatory?

-Form "wolf packs" that feed on bacteria via secretion of hydrolytic enzymes that reach sufficient concentration when in packs

Describe quorum sensing.

-Ability of bacteria to communicate & coordinate behavior via small molecules; applies to both intra & inter species communication
-Purpose: coordinate certain behavior based on density of bacteria

What functions do bacteria use quorum sensing for?

-Adaptation to availability of nutrients
-Defense against microbes which compete for same nutrients
-Avoidance of toxins
-Avoidance of host's immune system

What are the 3 compounds used for quorum sensing?

-Oligopeptides
-N-acyl Homoserine lactones (AHLs)
-AI-2 INTER species communication

What is a biofilm?

-Structured community of bacteria enclosed in a self-produced EC polymeric matrix (glycocalix, slime), adherent to inert or living surfaces
-NOT a pure culture; have different physiological states (not uniform amount of nutrients, oxygen)

What are bacteria protected from inside biofilms?

-Predators (amoeba)
-Phages
-Biocides (Chemical, physical)
-Antibiotics
-Immunophagocytes
-Antibodies

Why is it important for organisms in a biofilm to be in different physiological states?

-Organisms who are starving and are in stationary phase (dying and replicating are equal; will eventually decrease in numbers); these organisms are more resistant to environmental factors as opposed to rapidly growing cells

What are 4 common steps in infections?

-Encounter (contact)
-Entry (portals)
-Establish infection (colonization)
-Cause damage (clinical manifestation)

What is pathogenicity?

-Measure of ABILITY to cause disease
-Determined by the genetic make-up
-Infections dose may be used as a measure

What is virulence?

-Measure of the severity of the disease it is capable of producing (frequency of lethal infections)
-Can be measured by lethal dose

What do virulence genes code for?

-Factors allowing pathogen to invade the host

Describe the concept of "pathogenicity island".

-Section of an organisms' genome was apparently transferred from another pathogenic organism
-The section of the other's genome often encodes for virulence factors (e.g. protein secretion system, toxin production)

What are two general attachment features of pathogenic bacteria?

-Pili (fimbriae - hollow fibrils w/ tips to bind host cells)
-Adhesions (surface proteins that assist binding to host cells)

Describe the 5 categories of protein exotoxins.

-Cause host cell membrane leakage (e.g. hemolysis of RBCs)
-Block protein synthesis of host cell
-Block 2nd messenger pathway
-Superantigens overstimulate immune system
-Proteases cleave host proteins

Describe the process of the AB toxins.

-The B subunit (often 5 B subunits form a "pore") binds to the host cell & admits the A subunit into the cell
-The A subunit has toxic activity

Give two examples of diseases caused A subunit toxicity (of AB toxins).

-ADP-Ribosyltransferase = enzyme that can cause:
1 Diptheria: ribosylates elongation factor 2; blocks ribosome function & cell dies
2 Cholera: ribosylates to overactivate cAMP (which activates ion transport & H2O follows leading to diarrhea

What are the 2 active toxins in anthrax & what is their function?

-Edema factor raises cAMP levels (causes swelling, fluid secretion)
-Lethal factor cleaves protein kinases (blocks immune system from attacking)

What is the action of gram negative lipopolysaccharides in subverting its host?

-Component of the outer membrane
-Endotoxin in lipid A component
-Activates inflammatory response
-Can cause toxic shock

Describe the type 1 protein secretion pathway.

-There's a pore that goes from the cytoplasm membrane all the way through outer membrane of bacteria; toxins are transported to the exterior of the cell via this system

Describe the type 2 protein secretion pathway.

-Similar to a pilus; can extend and retratch
-Rams the protein through the outer membrane & into the host's cell
-Can also be used for motility

Describe the type III protein secretion pathway.

-Injects protein into cell like a hypodermic needle; injected proteins cause host to engulf bacterium
-Some genes for this system occur on pathogenicity island

What are some methods pathogens use in surviving WITHIN the host cell?

-Some pathogens use hemolysin to break out of host cell once phagocytized
-Some pathogens secrete proteins to prevent fusion of phagocyte w/ lysosomes
-Some pathogens mature in acidic enviro w/ lysosomes in phagocyte

What are some methods pathogens use in surviving OUTSIDE the host cell?

-Some pathogens secrete a thick capsule
-Some pathogens make proteins to bind antibodies
-Some pathogens cause apoptosis of phagocytes
-Some pathogens alter surface antigens periodically

What property of influenza (and most viruses) allows them to evade detection by the immune system?

-Creates new epitopes on the surface = antigenic drift

What are some factors that allow for antigenic drift?

-RNA polymerase does not correct replication errors
-Frequent mutations in hemagluttinin gene

What was the genetic basis of the 1918 flu pandemic?

-Two strains infected a host at the same time
-Recombined viruses have a mix of chromosomes (caused immediate alteration of several genes)

How is West Nile Virus detected in horses?

-Draw blood and look for antibodies to the virus (don't directly look for virus)

What is unique about the structure of the West Nile Virus?

-The virus is a nucleic acid that can be admitted into the host cell
-Contains a single open reading frame, which allows it to act like mRNA in the host cell (translated into proteins in the host cell)

What are the steps of transmitting to admittance of TB?

-Transmitted by aerosols
-Taken up by alveolar macrophages
-Survives inside the host cell and surrounds itself in "tubercles"; latent infection is the real problem

What (mainly) determines the outcome of TB?

-The immune response determines the outcome
-Most of the damage occurs because of the immune system's response to infection

What is unique about mycobacteria?

-Not the usual virulence pathways
-Can sit dormant inside host cells
-Allows bacteria to avoid host antibodies

What are some characteristics of pathogenic E. coli?

-Strains associated with hemorrhagic colitis that produce Shiga-like toxins; attaching and effacing lesions
-Low infectious dose

What symptoms present with most pathogenic E. coli?

-Severe abdominal cramps, watery and most likely blood diarrhea, vomiting and nausea

What function of pathogenic E. coli yields the symptoms?

-Bacteria colonize the intestines & produce a powerful toxin (via the type III secretion pathway)

What is hemolytic uremic syndrome and what causes it?

-Most commonly found in children and elderly as a result of severe E. coli
-E. coli trans-locates to kidney and causes acute kidney failure because of destroyed blood cells

What is an epidemic?

-Disease affects many people AT THE SAME TIME

What is an endemic?

-Disease affects people in "spurts" at a time, but never at the level of an epidemic

What is the difference between a common source epidemic and and a propagated one?

-Propagated gains speed as it goes along, gathering more victims
-Common source usually has a single, short lived spike and then decreases

What is the significance of subytyping microbes?

-Epi investigations
-Virulence characterization
-Environmental tracking
-Evolution
-Source determination

What are the three types of conventional subtyping?

-Phage typing
-Biotyping
-Serotyping

Why is it not very feasible to type the entire genome in clinical settings and what are some other options?

-RFLP (gives less bands because of discriminatory probes)
-Pulse-filled gel electrophoresis (high resolution separation of very large DNA fragments; low frequency cutting enzyme); is the "gold standard"

What is a pandemic?

-Epidemic of infectious disease that is spreading through human populations across a large region; for instance a continent, or even worldwide

Exam 1

Microbiology 303 with Charles Kaspar/diana Downs/jorge Escalante at University of Wisconsin - Madison

About this deck

About StudyBlue

Sign up (free) to study this.

About this deck

About StudyBlue