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Microbiology test2
CH 3,4,5
| Term | Definition |
|---|---|
| nucleus | contains most of the cells DNA, site of transcription; double membrane containing pores, outer w/ER |
| mitochondria | energy production; double membrane, DNA, independent replication; not present in amitochondrites |
| chloroplast | photosynthesis; double membrane, DNA, independent replication; unique to photosynthetic organisms |
| Rough ER | translation and protein folding; protein-synthesizing ribosomes attached to it |
| Golgi Apparatus | modifies, sorts, and transports proteins; connect to ER thru a series of vesicles |
| Vacuole | storage and structure; food vacuoles serve as sites of digestion, contractile vacuoles help maintain water balance |
| Lysosome | digestion of macromolecules; has digestive enzymes |
| Peroxisomes | breakdown of fatty acids; has oxidative enzymes like catalase and oxidase |
| Hydrogenosome | production of H2 and ATP; double membrane, found in amitochondriates may be remnant of mitochondrion |
| Nucleolus | ribosome synthesis; non-membrane bound structure within the nucleus |
| Bacteria Cell Wall- Gram Positive | thick peptidoglycan layer (40nm; 40-80% of cell wall dry weight); suface of peptidoglycan layer decorated w/teichoic acid |
| Bacteria Cell Wall- Gram Negative | thin peptidoglycan layer (2nm; 5%); outer membrane has phospholipid inner leaflet and lipopolysaccharide outer leaflet |
| Archaea Cell Wall-Methanogens | glycopeptides or pseudopeptidoglycan |
| Archaea Cell Wall-Halogens and Hyperthermophilic: | glycoproteins |
| Eukarya Cell Wall- Fungi | chitin |
| Eukarya Cell Wall- Algae | cellulose; diatoms have cell walls (termed fistulas) made of silicon dioxide, proteins, and polysaccharides |
| Eukarya Cell Wall- Protozoa | none; but glycoproteins may be assembled into a cell wall during particular developmental stages to produce cysts or spores |
| Fungi | Model Organism-Saccharomyces cerevisiae heterotrophic non-motile cell wall nucleus mitochondria |
| Protozoa | Model Organism-Giardia lambdia heterotroph swimming: cilia/flagella ; amoeboid:pseudopods nucleus mitochondria |
| Slime Mold | Model Organism-Dictyostelium discoideum heterotrophic amoeboid: pseudopods nucleus mitochondria |
| Algae | Model Organism-Chlamydomonas phototrophic non motile or swimming:flagella cell wall nucleus mitochondria chloroplast |
| Heterotrophic | gaining energy and cellular building blocks by consuming organic food |
| Photosynthetic | gaining energy from sunlight and cellular building blocks by fixing carbon dioxide from the atmosphere |
| Plasmodium | formed when the individual cells of acellular slime molds fuse together to form a multi nucleated aggregate |
| drug treatments target? | cellular structures in the pathogen that are different from those of the host |
| Plasmodium falciparum | causes cerebral malaria that is transmitted by the Anopheles mosquito-malaria kills around 1 mil/yr;no effective vaccine exists |
| Trypanosoma brucei | causes African sleeping sickness is transmitted by a tsetse fly |
| Toxoplasma gondii | causes a common infection transmitted via cat feces or raw meat; can cause significant neurological problems in fetus'; remains in the host and can re-emerge if host is immunocompromised |
| why fungi are well suited to cause plant infection | the durable nature of their spores readily permits them to survive in soil between crops and during inclement weather conditions |
| Plytophthora infestans | a water mold (protozoa most closely related to brown algae and diatoms) that causes potato diesease |
| Beneficial roles of microbes | primary producers (providing energy) biodegraders (recycling nutrients) |
| Protozoa | "first animals" principal hunters and grazers of the microbial world maintains the balance of bacterial, algal, and other microbial life important food source for larger creatures; basis of many food chains |
| Protozoa-normal microbial flora for animals | live in the guts of insects and mammals helps to break down complex food particles into simpler molecules |
| 4 main Subgroups of Protozoa | ciliates flagellates sarcodina apicomplexans |
| Ciliates | unicellular protists that can be recognised by their hairlike 'cilia' which is used for locomotion and for feeding. |
| Flagellates | single celled protists with one or more flagella, which are whip-like organelles often used for propulsion. |
| Sarcondina | unicellular protists that move with pseudopodia (false feet) and are very slow |
| Apicomplexans | unicellular, spore forming protists that lack motility; stuck in this group until a mode of transportation is provided |
| Fungi | intertwining threads of cells (hyphae) comprise mycelium some damage crops and plants and cause human disease secrete digestive enzymes to break down complex food sources into smaller components they can absorb major decomposers and recyclers |
| Symbiotic relations | work together to the benefit of both |
| Symbiotic relations - Mycorrhizae | plants provide the fungi nutrients and a home in their roots the fungi help the plants absorb and concentrate essential nutrients |
| Symbiotic relations- Lichens | fungi + green algae or cyanobacteria enable the organisms to grown in places that neither the fungi nor the algae or cyanobacteria could grow independently |
| Algae | plant-like microorganisms that preceded plants light absorbing chloroplasts, producing O2 via photosynthesis foundation for the aquatic food chain most unicellular algae live in water, some dwell in moist soil, and others join with fungi to form lichens |
| 75% or more of the oxygen in the planet’s atmosphere is produced by? | photosynthetic algae and cyanobacteria |
| Green Algae (algae) | plant-like algae (probably gave rise to multicellular plants) growing in large masses, can form visible layers of slick, green scum on the surfaces and sides of ponds, puddles or damp soil |
| Diatoms (algae) | shell-like, brittle cell walls made out of silica (glass) and pectin walls are 2 interlocking halves or shells that fit together like a pillbox diatomaceous earth or diatomite-used in pool filters, abrasives |
| Phyla of Archaea | Crenarchaeota Euryarchaeota Nanoarchaeota Korarchaeota |
| Nanoarchaeota | Nanoarchaeum equitans is the only member (so far) 16S rRNA possibly one of the smallest living organisms on Earth! |
| Euryarchaeota | methanogens halophiles |
| Methanogens | reduce CO2 with H2 to produce methane (CH4) and water (H2O) in an unusual reaction energy released can be used to fix carbon strict anaerobes diverse but share a common metabolic property |
| Methane produced in human gut and swamp sediments form? | gas from humans and combustible air from swamps |
| Halophiles | require NaCl concentration greater than 1.5M extremophilic organisms that thrive in environments with very high concentrations of salt |
| High salt environments | Great Salt Lake in Utah Dead Sea between Israel and Jordan these areas vary between 5 to 34% salinity the ocean is typically 3.5% salinity (0.6M)! |
| Classification of media is based on | consistency components |
| Consistency | solid semisolid liquid |
| Components | selective (selects for a group of organisms and inhibits the growth of others) differential (visual differentiation between organisms) enriched (has something in it that will help grow a picky eater) |
| Properties of Archaea | phylogeny structure evolution |
| Phylogeny | growth requirements halophile, thermophile, psychrophile |
| Thermophile/Hyperthermophile | thrives at relatively high temperatures, between 45 and 122 °C (113 and 252 °F) |
| Psychrophile | capable of growth and reproduction in cold temperatures, ranging from −15°C to +10°C |
| Structure of Archaea | .5-5 μm in diameter similar shapes to B/E like B,usually possess singular, circular chromosomes & lack a membrane-bound nucleus DNA is complexed w/histones like E many DNA replication enzymes look like those of E structure is unique to this domain |
| Evolution of Archaea | may have branched off from Bacteria development of histones may have been an early “branch point event” unique plasma membrane is not required to thrive in harsh environ. |
| Crenarchaeota | acidophiles, basophiles, mesophiles, and psychrophiles these microbes possess multiple adaptations to thrive often detected by rRNA gene sequences but not by cultivation possibly very important to biogeochemical cycling of C and N in the oceans |
| Mesophile | capable of growth and reproduction in temperatures ranging from15-40°C |
| new phylum of Archaea in flux? | Cenarchaeum symbiosum resides in a marine sponge. its sequence shares some genes with crenarchaeotes but also some with euryarchaeotes |
| Virus | small, acellular particles obligate intracellular parasite typically between 10 to 100 nm genomes typically a few thousand-200,000 nucleotides in length single or double stranded DNA or RNA capsid envelope (in some) |
| Obligate intracellular parasite | cannot replicate independently |
| Capsid | protective protein shell around the genome |
| Nucleocapsid | capsid and genome together |
| Envelope | lipid bilayer that surrounds the capsid of some viruses |
| Host cells are needed by viruses for? | replication translation transcription and/or genomic replication in many viruses |
| Viruses must possess ? bc of their dependence | a mechanism for entering and exiting a host cell |
| Bacteriophage | viruses that infect bacteria |
| Symmetry of viruses | capsids often exhibit either helical or icosahedral shapes viral capsids can sometimes take on irregular or complex shapes |
| Naked virus | no plasma membrane |
| Enveloped virus | |
| Replication Cycle of viruses | A virus must: stick to a host cell (adhere) get into the cell (penetrate) release its genome (uncoat) express its genes to make proteins (synthesis) put everything together (assembly) and get the new virus particles out (exit) |
| Entry (replication cycle) | most important part in the viral replication cycle |
| Entry into an animal cell | endocytosis of a non-enveloped virus membrane fusion of an enveloped virus endocytosis of an enveloped virus |
| Entry into a plant cell | often depends on some damage to the plant tissues to open a spot in the cell wall insects feeding on plants wind damage hail/rain damage fire damage human-induced damage |
| Entry into bacteria steps 1 and 2 | tail fibers attach 2 receptors conformational change in tail fiber bring base of tail n contact w/host cell surface |
| Entry into bacteria steps 3 and 4 | rearrangement of tail proteins allows inner core tube proteins to extend into cell wall contact w/plasma membrane initiates transfer of DNA thru a pore formed in the lipid bilayer |
| Viral diseases began? | as a science in late 1800s, when infectious tobacco mosaic virus was isolated in a filtered, bacteria-free fluid by Ivanovski, then Beijerinck |
| Capsomeres | symmetrically arranged subunits that make up the capsid of all viruses |
| Helical morphology | the capsomeres form a helix and the capsid resembles a hollow tube |
| Icosahedral morphology | the capsomeres form an icosahedron (20 sided polygon) with each capsomere making up a face |
| virion | complete viral particle the nucleocapsid in phages and plant viruses an additional membrane or envelope surrounding the nucleocapsid in all animal viruses |
| Coevolution hypothesis | viruses may have originated prior to or at the same time as the primordial cell and have continued to coevolve with these hosts |
| Regressive hypothesis | viruses may represent a form of life that has lost some of its essential features and has become dependent on a host |
| Progressive hypothesis | viruses may have originated when genetic material in a cell gained functions that allowed the DNA or RNA to replicate and be transmitted in a semi-autonomous fashion |
| retrotransposons | pieces of DNA capable of moving to new locations within a genome |
| lytic(virulent) bacteriophages | the virus replicate within the bacteria and eventually lyse or destroy the infected cells |
| lysogenic (temperate) bacteriophages | virus that exists in a latent state within a host bacterial cell as the phage genome is integrated into the bacterial genome; can replicate lytically harder to quantify |
| Prophage | phage DNA integrated integrated into host DNA; latent form of temperate phage |
| Lysogen | the cell containing the prophage |
| Persistent infection | release of virions from host cell does not result in cell lysis infected cell remains alive and produce virus indefinitely |
| Latent infection | delay between infection by the virus and lytic events |
| transformation | conversion of normal cell into a tumor cell |
| How do we grow viruses considering: | viruses are much trickier to work with than bacteria they are very small they only replicate within appropriate host cells because of these traits, various strategies are used to amplify and quantify viruses |
| Viral cultivation- Overlay Method (only method disc) | petri dish with a nutrient agar pour liquid agar with phage & bacterial host mix over the nutrient agar base virus creates “plaques” 1 virion gives rise to many viruses; 1 virus = 1 pfu (plaque forming units); count the pfu to get the # of pfu/mL |
| Plaques | areas of lytic destruction or an area of clearing in the “lawn” of bacteria indicating cell death or lysis |
| Viral cultivation of animal viruses | tissue culture of host cells must be used to grow the targets for the viruses 1950s; many of these tools developed from HeLa cells CPE can be observed in virally infected cultured cells these cultures must be kept sterile and bacteria-free |
| Cytopathic effects (CPE) | visible changes in cell morphology often associated with cell damage or death |
| Viral Purification | usually begins with simple filtration to remove large cells and cellular debris then viruses can be purified and concentrated with differential centrifugation or gradient centrifugation |
| Gradient centrifugation | depends on different densities of viral components and particles each piece of different density will settle into a different area (“band”) of a density gradient after centrifugation |
| Differential centrifugation | low speed intact cells and large cellular debris collect at the bottom of tube supernatant ultracentrifuged causing virions to pellet supernatant removed and virions resuspended in a smaller volume of liquid resulting in purified & conc. viral solution |
| Viral Quantification methods | plaque assay direct count hemagglutination assay endpoint assay |
| Plaque Assay | this is useful in phages and plant viruses virus is diluted and placed on target cells plaques are counted to determine plaque-forming unit (PFU) titer of original suspension |
| Direct Count | an electron microscope can be used to visualize a known volume of material, counting viruses within it and scaling up to determine titer requires expensive, specialized microscope doesn’t differentiate btwn infectious and non-infectious viral particles |
| Hemagglutination Assay | exploits trait of some viruses to stick to rbc’s causing them to form a gel mat pros: cheap, easy, fast, no microscope needed cons: some viruses wont do this; doesn’t differentiate viable/non-viable viruses; doesn’t give a virus number |
| Endpoint Assay | tissue culture infectious dose 50 (TCID50): amount of virus needed to induce a CPE in 50% of cultured cells lethal dose 50 (LD50): amount of virus needed to kill 50% of test animal subjects |
| Virus Names | simple letter/number combination (T4 Phage) organism(s) they infect (tobacco mosaic virus) location of discovery (Ebola River, Zaire) appearance (coronavirus) disease caused (herpes simplex virus) |
| Virus classification scheme | ICTV= International Committee on Taxonomy of Viruses Classify viruses based on Order, Family, Subfamily, Genus, and Species The Baltimore classification system |
| The Baltimore classification system | |
| Synctium | rounding and detachment of infected cells or the fusion of individual infected cells into a large, multinucleated mass |
| hemagglutination | when rbc's stick together |
| viroids | infectious agent that infects plants naked RNA extremely small internal complementarity increased resistance to ribonucleases |
| TSE | progressive neurological diseases characterized by impaired mental functions and hoes in the brain |
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MamaSadie
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