Micro Lecture Final – Flashcards
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Unlock answers| microbiology |
study of organisms too small to be clearly seen by unaided eye organisms are simple and lack differentiated cells and distinct tissues small size, simple undifferentiated structure |
| cellular organisms |
| fungi, protists, bacteria, archaea |
| acellular organisms |
| viruses, viroids, satellites, prions |
| characteristics of cellular entity |
presence of plasma membrane is main distinguisher also has nucleus |
| prokarotic cell |
lacks true membrane bound nucleus still considered a cell since it has a plasma membrane |
| eukaryotic cell |
membrane bound nucleus more complex morphology usually larger |
| 3 domain classification system |
based on ribosomal RNA genes 1. bacteria 2. archaea 3. eukarya |
| Domain Bacteria |
all prokaryotic all are single-celled most have peptidoglycan in cell wall can survive broad range of environments most are non-pathogenic nutrient recycling
|
| cyanobacteria |
| produce oxygen as a result of photosynthesis |
| Domain Archaea |
all prokaryotic unique ribosomal RNA sequences lack peptidoglycan unique fatty acids/membrane lipids many found in extreme environments no pathogenic species known to humans |
| Domain Eucarya |
all eukaryotic animals, plants, eukaryotic microorganisms m/o's include protists, protozoa, slime molds, water molds, fungi (yeast, mold) generally larger |
bacteria/archaea types of microbes |
rigid cell wall, no nuclear membrane 1-5 um
prokaryote
|
fungi types of microbes |
rigid cell wall, nuclear membrane 4-25 um
eukaryote |
protozoa types of microbes |
no rigid cell wall, nuclear membrane
eukaryote |
algae types of microbes |
rigid cell wall, nuclear membrane
eukaryote |
helminths types of microbes |
parasitic flat and round worms don't need a microscope to see but still relatively small |
| viruses |
acellular cannot multiply outside host smallest of all microbes cause a range of diseases
|
| virus basic structure |
nucleic acid(genome) - ss/ds DNA or ss/ds RNA protein coat (capsid) some have an envelope |
| bacteriophage |
attack bacteria usually ds DNA
|
| eukaryotic viruses |
| naked or enveloped virus |
| Antony von Leewonhook |
first person to observe and describe microorganisms accurately
used primitive form of microscope 300x magnification |
| Louis Pasteur |
refuted spontaneous generation theory fermentation pasteurization contributed to germ theory vaccine development |
| Agostini Bassi |
| showed disease of silkworms was caused by a fungus |
| Louis Pasteur |
| showed that a pebrine disease of silkworms was caused by a protozoan |
| Joseph Lister |
system of surgery designed to prevent m/o's from entering wounds and treating instruments and dressings used phenol indirect evidence m/o's were causal agents of disease |
| Robert Koch |
established direct evidence that m/o's cause disease 4 postulates |
| Jacob Henle |
| Koch's mentor whose criteria were used to develop Koch's postulates |
| Koch's postulates |
1. microbe must be present in all with disease and associated with lesions of the disease 2. microbe must be isolated in pure culture 3. isolated microbe must cause disease when administered to another healthy patient 4. microbe must be isolated in pure culture with the second infected patient |
| what was used for Koch's postulate testing? |
| isolated anthrax in cattle |
| Edward Jenner |
cowpox lesions to protect people against smallpox "attenuated vaccine" immunology field |
| Sergei Winogradsky and Matinus Beijerinck |
studied soil m/o's discovered numerous metabolic processes oxidizing bacteria (use other substances as energy source) selective media microbial ecology |
| light microscope |
most are compound image formed by action of >2 lenses use light source |
| bright field microscope |
dark image on light background several objective lenses
|
| parfocal |
| microscope remains in focus when objectives are changed |
| refractive index |
measure of how greatly a substance slows the velocity of light based on angle, speed
determines direction and magnitude of bending based on refractive index differences between 2 media |
| focal length |
distance between center of lens and point at which light rays converge decreasing focal length increases the magnification |
| resolution |
resolving power ability of lens to separate or distinguish small objects that are close together
shorter wavelength increases resolution |
| numerical aperture |
n(sin)theta relationship between focal length and working distance |
| resolution equation |
decreasing d increases resolution decreasing lambda increases resolution increasing numerical aperature increases resolution |
| dark field microscope |
bright image on dark background used on living unstained organisms |
| phase contrast microscope |
converts slight differences in refractive index and cell density into easily detected variations in light density
observes living cells, internal structures
uses dark field stop |
| fluorescence microscope |
stain specimens with fluorochromes expose to UV light with short wavelength and high energy |
| confocal microscopy |
confocal scanning laser microscopy (CLSM) sharp composite 3D image using lawser beam, aperture, and computer interface
laser beam can view layers and then superimpose them for 3D |
| electron microscopy |
electrons replace light as illuminating source short wavelength results in higher resolution |
| transmission electron microscope (TEM) |
transmitted electrons under vacuum which reduces scatter and are used to produce a clear image
complicated staining procedure |
| Scanning Electron Microscope (SEM) |
3D image of surface features electrons released from atoms on an object's surface (secondary electrons) easier preparation |
| 2 forms of scanning probe microscopy |
1. scanning tunneling 2. atomic force |
| scanning tunneling microscope (SEM) |
needlelike probe with 1 atom at tip electrong cloud just touches surface atom to create tunnel current may examine objects immersed in water |
| atomic force microscope |
cantilever moves up and down to maintain constant height above organism's surface good for samples that don't conduct electricity well |
| bacterial plasma membranes |
absolute requirement for all living organisms encompasses cytoplasm selectively permeable barrier interacts with external environment through receptors, transport systems, metabolixc processes
fluid mosaic model: lipid bilayer in which proteins float |
| 2 types of membrane proteins |
1. peripheral (loosely connected, easily removed) 2. integral (ampipathic, not easily removed) |
| membrane lipids |
eukaryotic: contain sterols bacterial: hopanoids (sterol-like molecules)
saturation levels of membrane lipids reflect living conditions unsaturated: lower melting point cold environments have more unsaturated fatty acids |
| bacterial cell wall |
peptidoglycan layer rigid structure just outside plasma membrane G(+) or G(-) based on peptidoglycan layer maintains shape protects against osmotic lysis and toxic materials may contribute to pathogenicity |
| Gram positive cell wall |
thick peptidoglycan layer purple aka monoderm inner wall zone/periplasmic space between peptidoglycan and plasma membrane large amount of techoic acids few proteins in periplasmic space some have protein layer on surface of peptidoglycan |
| Gram Negative Cell Wall |
thin peptidoglycan, outer membrane, and plasma membrane with periplasmic space outer membrane composed of lipids, lipoproteins and Lipopolysaccharide (LPS) no techoic acid many enzymes in periplasm |
| LPS |
Lipopolysaccharides 3 parts 1. O side chain (O Ag) 2. core polysaccharide 3. lipid A
restricts entry of bile salts endotoxin |
| Peptidoglycan structure |
mesh-like polymer of identical subunits 2 alternating sugars (NAG and NAM) alternating D and L amino acids strengthens structure helical shape peptidoglycan chains are crosslinked by peptides for strength interbridges may form variety of amino acids form bridge to cross length strand so strands can become iterconnected |
Additional layers outside cell wall
|
1. Capsule 2. Slime Layer 3. S Layer |
| Capsule |
usually composed of polysaccharides well organized, not easily removed from cell visible in light microscope via negative stain protective advantages (resistant to phagocytosis, protect from desiccation, protect from viruses and other predators) |
| slime layer |
similar to capsule but difuse and unorganized still made of polysaccharide easily removed may aid in motility |
| S Layer |
regularly structured layers of protein or glycoprotein that sel-assemble potential use in nanotechnology |
| archaeal cell wall |
varies between species but usually consists of complex heteropolysaccharides lack peptidoglycan but some have pseudomurein (looks like peptidoglycan but only L amino acids and NHAc instead of NAM) most commen cell wall is S layer unique lipids monolayer instead of bilayer |
| archaeal membranes |
composed of unique lipids isoprene units (5 carbon, branched) ether linkages to glycerol (not ester) some have monolayer instead of bilayer structure |
| cytoplasmic matrix |
substance in which nucleoid, ribosomes, and inclusion bodies are suspended lacks organelles bound by unit membranes mostly water no true cytoskeleton but homologs of eucaryotic cytoskeletal elements |
| intracytoplasmic membranes |
plasma membrane infoldings in many photosynthetic bacteria analogous to thyladoids of chloroplasts rxn centers for ATP formation |
| inclusions/inclusion bodies |
aggregates of organic or inorganic material thare are stockpiled by cell for future use free in cytoplams or enclosed by membrane vary in compostion |
| inclusion body examples |
granules of glycogen, PHB as carbon storage
gas vacuole/vessicle provide buoyancy for many cyanobacteria |
| magnetosomes |
found in aquatic bacteria contain magnetite particles for orientation in earth's magnetic field bacterial cytoskeletal protein MamK helps from magnetosome chain |
| ribosomes |
sites of protein synthesis complex structures consisting of protein and ribosomal RNA made up with different subunits S = svedberg unit (fxn of weight, volume, shape)
|
| nucleoid |
irregularly shaped region in bacteria and archaea no nuclear membrane location of chromosome and associated proteins usually 1 per cell closed circular, ds DNA molecule supercoiling and nucleoid proteins (HU protein) aid in folding |
| plasmids |
extrachromosomal DNA in bacteria, archaea, some fungi sm, closed circular DNA molecules exist/replicate independently of chromosome genes on plasmids are not essential but may confer selective advantage may exist in many copies in the cell |
| external structures |
extend beyond cell envelope in bacteria and archaea protection, attachment, horizontal gene transfer, cell movement 1. pili and fimbriae 2. sex pili 3. flagella |
| pili and fimbriae |
short, think, hairlike, proteinaceous appendages up to 1000 per cell mediate attachment to surfaces type IV fibriae required for motility on solid surface uptake DNA via transformation |
| sex pili |
longer, thicker, and less numerous genes for transformation found on plasmids required for conjugation direct uptake from another cell not really sex but transfer plasmid from donor to recepient |
| flagella |
threadlike, locomotor appendages extending outward from plasma membrane and cell wall swimming and swarming behaviour, attachment, virulence factor |
| patterns of flagella distribution |
monotrichous: 1 flagellum polar flagellum: at one end of cell amphitrichoud: at each end lophotrichous: cluster at one or both ends peritrichous: spread over entire surface |
| parts of flagella (bacterial) |
filament: extends from cell surface to tip. hollow rigid cylinder composed of flagellin protein sometimes containing outer sheath basal body: series of rings that drive flagellar motor hook: links filament to basal body |
| flagellar synthesis |
complex process similar to type III secretion system flagellin self-assemble with help of filament cap growth from tip |
| archaeal flagella |
thin more than one type of protein not hollow hook and basal body difficult to distinguish more related to type IV secretion growth at base |
| periplasmic flagella |
axial filaments found in spirochetes exhibit flexing and spinning movements located in periplasmic space multiple flagella intertwined and wind around cell |
| bacterial endospore |
complex, dormant structure formed by some bacteria resistant to numerous environmental conditions |
| factors that make endospore so hardy |
calcium complexed with dipicolinic acid small, acid-soluble, DNA binding proteins (SASPs) dehydrated core spore coat and other protective layers DNA repair enzymes
|
| virus |
protein + nucleic acid
|
| viroid |
| only RNA |
| satellite |
| nucleic acid (DNA or RNA) |
| prion |
| only protein |
| Charles Chamberland |
| developed porcelain bacterial filters used in later discovery of viruses |
| Dimitri Ivanowski |
demonstrated that the causative agent of tobacco mosaic disease passed through bacterial filters thought agent was a toxin |
| virion |
complete virus particle consists of >1 molecule of DNA or RNA enclosed in protein coat (nucleocapsid) may have additional layers and projecting spikes 10-400nm diameter cannot reproduce independently outside living cells |
| lysogenic conversion |
when a temperate phage causes a change in the phenotype of an infected bacterial cell
|
| prophage |
| DNA of a temperate phage |
| protomer |
| protein subunits that make up capsid |
| viral envelope |
| usually arise from host cell plasma, nuclear, or ER mambranes |
| envelope proteins |
may project from envelope surface as spikes or peplomers mostly glycoproteins involved in viral attachment may have enzymatic or other activity used for viral ID M protein (nonglycosylated) on inner surface for stabilizing |
| virion enzymes |
some are associated with the envelope or capsid but most are within capsid may play a role in nucleic acid replication |
| helical capsids |
shaped like hollow tubes with protein walls protomers self-assembe |
| enveloped virus with helical nucleocapsid |
7-8 segmented nucleocapsid RNA each coated by capsid |
| icosahedral capsids |
icosahedron = regular polyhedron with 20 equilateral faces and 12 vertices 1 of natures favorite shapes |
| viral multiplication steps |
1. attachment or adsorption to host 2. entry or penetration (uncoating) 3. uncoating of genome 4. synthesis 5. assembly 6. release |
