Week 1 Flashcards
Fundamentals
What creatures does the study of microbiology include?
Bacteria, viruses, fungi, parasites
How much biomass does bacteria make up? (of the world’s total)
50%
How many more bacterial cells are there than human cells within the body?
10x
How much of the world’s O2 does bacteria produce?
50%
What three things do bacteria do that are super important for the environment?
1)Decomposition. 2)Nitrogen fixation 3) Oxygen production 4*)bioremediation
What percent of microbes cause disease?
1% Most bacteria assist in digestion or protect us from other bacteria
What are the four major microb classifications
Viruses, fungi, protozoa, bacteria/prokaryotes
What are the six general virus characteristics
1) Obligate intracellular parasites. 2) No cytopasmic membrane, cytosol, organelles* 3)Causes infections in animals, plants, fungi, and bacteria 4)Causes ‘plauges’ 5)not alive (no metabolic pathaways, no growth or response, no independent reproduction). 6)infect cells metabolic pathways
what are the four general characteristics of fungi
1) (chemo)heterotrophic - dont fix carbon (photosynthesis), but use them for growth. 2)chitinous cell walls. 3) uni or multicellular. 4) closely related to animals
What six things do fungi do that are significant to the environment
1) Decompose dead organisms (saprophytes). 2)Helps plants absorb water and minerals (Symbionts/commensals). 3)Used for food/bev manufacturing 4)Used for antibiotics. 5) used for research 6)Can cause infection (30% of cause)
What are the four characteristics of protozoa?
Eukaryotic, unicellular, lack of a cell wall, motile (bacteria are motile as well, but only flagella)
What does medical microbio focus on?
Pathogens that cause (human) disease
what family is TB from
Mycobacterium tuberculosis
What three ways can Protozoa be motile?
Cilia, flagella, or pseudopodia (exceptions are apicomplexans subgroup)
Where do protozoa live?
Moist environments. Critical members of planktons
Are protozoa pathogenic?
Yes, but very few
What genetics do prokayotes (not viruses) have?
DNA: single, circular chromosome in the nucleoid area (no cell wall). (plasmids encode specialized genetic info, EG pathogenicity or drug resistant genes)
Eurkaryotic cell characteristics (5)
Nucleus (membrane bound genetic), Internal membrane-bound organelles, larger 10-100x bigger than prokaryote, complex, includes: algae, protozoa, fungi, animals, plants
prokaryotic cell characterics (5)
Lack nucleus (nucleoid instead), lack mitotic apparatus, Lacks various interial membrane-bound structures, small (less than 1um in diameter), simple structure, include bacteria and archaea
What is the nucleoid
An area where a single, cilular chromosome is, without a nuclear membrane
What else is in the cytosol of a protkaryote?
Plasmids, Ribosomes, nucleoid
What is the cell envelope? what does it do?
Protects the cell from osmolarity, chemicals, antibiotics. Made out of the plasma membrane and the cell wall
What is the cell wall mostly composed of for a prokaryote?
Peptidoglycan
What does the cell wall do? what does the plasma membrane do? what is the cell envelope?
Cell envelope= Cell membrane + Cell wall
-Cell wall: Protects the cell from environment, helps with cell attachment
-Cell membrane: Selective permeability, concentration/electrical gradient maintenance, photosynthesis
What are the two types of bacterial cell envelope structures look like? Outside to inside
Gram-positive: Thicc peptidoglycan layer, plasma membrane. Held together with teichoic acid.
Gram-negative: Outer membrane with lipopolysaccarides as well as other PM stuff.
What are lipopolysaccharides? What do they do? where are they located?
They are located on the outside of a gram negative outer membrane. They are used in cell structure, protection, and signaling
What causes the stiff thick structure of a gram postiive peptidoglycan cell wall
Pentaglycine bridges
What causes serotypes in gram-pos bacteria
Teichoic and lipoteichoic acid
What is the cell wall component that determines serotype in gram-negative organisms
lipopolysaccharides (LPS)
What is an acid-fast organism?
Has a waxy cell wall due to mycolic acid, and so cannot be stained with water-based stains. Must use a Ziehl-Neelson stain, which uses acid to penetrate the cell wall
Other external bacterial structures
Glycocalyx: a gelatinous, sticky stubstance that surrounds the outside of the cell.
Flagella: long stucture that helps with cell movement
Fimbriae/pili: small hair like structures that promote adhesion of cell
Bacterial spore/ endospore: unique structure produced by bacterium in unfavorable conditions
What is an endospore?
Unique structures (only some bacteria) to protect them against unfavorable condintions
Gram positive or negative? Lipoteichoic acid, teichoic acid, and lipopolysaccharides (LPS)
lipoteichoic acid and teichoic acid : positive
LPS: negative
What is a glycocalyx? What are the two types
Gelatinous polysaccharide and protein complex that surrounds the bacterium. Used for anchorage, strength and desiccation resistance.
-Capsule: repeating layers of organic chemicals firmly attached to bacterium. Prevents cell recognition
- slime layer: loosely attached, water soluble layer. Helps with adhesion to surfaces.
What are the four ways/methods to classfiy bacteria?
-Media growth
-Microscopy
-biochem
-immunolocial
What is complex media? What is simple media?
Simple: just agar
Complex: additives that allows us to grow bacteria on solid-agar. Cannot grow viruses or paraistes because they need a host cell (obligate intracellular parasites).
What are the three categories of complex agar media? Give an example of each.
non-Selective: No antibiotics or anything to stop organisms from growing. Trying to get everything to grow (BAP, choco BAP)
Selective: elimates or reduces large numbers of irrelevant bacteria. (MAC for enterobacteriaceae, CNA agar for STS and streph)
Differential: Makes use of bacteria’s biochemical properities (EG pigment, enzyme secretion). (MAC with its lac + and lac - stuff) (Chrom agar shows pathogenic versus non pathogenic Ecoli)
What color does Salmonella/Shigella produce on MAC? how about Ecoli
Salmonella/Shigella: White
Ecoli: red
What is microscopy?
Using a microscope and a stain to see a bacteria. Includes light (type dependent on organism of interest), electron , confocal scanning laser, and scanning probe microscopy
What is Bright-feild microscopy
The normal one. Uses an objective and an ocular lens. Uses contrast differences with surrounding media to cause visability. Dead cell only
phase contrast light microscopy
use light that passes thru cells in different phases depending on material properties. A special condenser then is used to make a 2D image with greater contrast than bright-field. Used to see living cells
Differential interference contrast microscopy (DIC)
Uses polarized light in two beams that then converge to give the image inference –> more contrast. Good for living cells with fine detail with no staining. 3D image
What is Darkfield microscopy
uses a transmitter to prevent light from directly illuminating the specimen, causing a dark background. Allows to see different bacterial components or specimens that are difficult to see with direct lighting
What is flurorescence microscopy?
Organism is stained with a fluorescent dye, or immunofluorescence. Allows for greater contract and brighter illumination
electron microscopy
Best contrast and visulaization. Uses magnetic coils and electron beams to ‘see’ the bacteria
What are the two types of electron microscopy?
SEM: surface scan
TEM: Electrons move thru sample to see interior
What is a direct examination of bacteria?
Samples are suspended in solution, but not stained. Includes: water, KOH 10% for protein dissolve, india ink or lugol iodine (contrast, not staining)
What are some differential stains
Gram stain, acid-fast stain, iron hematoxylin stain, trichrome stain, ect … NOT Fluorscent stains
What is the oxidase test?
Does the organism has cytochrome-C oxidase?
What is the catalase test?
Does the organism have catalase to take care of toxic oxygen (OH)
What do antibodies read as the epitope on microorganisms?
LPS, flagella, or capsular antigens
What is an agglutination assay? What type of test is it?
An antibody is made to a specific microorganism or one of its compoents. The bacterial sample and the antibodies are put together. If positive, clumping will happen (at macroscopic level). This is a serological test
What are the four bacteria shapes?
Bacillus (rods), coccus, spirllum (spiral), Spirochete (corkscrew), vibria (comma)
How is subtyping determined (4)
Serologically. Biotyping (biochem tests). Antimicrobial susceptibiltiy testing. molecular methods (PCR)(using proteins, DNA, or RNA. Cannot recover organism, but doesn’t need isolation)
Why don’t you run pulsed-feild gel electrophoresis electrial feild linearly?
DNA is too big. It would litterially get stuck. It needs to be giggled along. was like pre-PCR
What are the four stages of binary fission?
1) cell elongation + DNA replication
2) Cell division starts: cross wall starts to form and DNA copies are pushed to opposite ends of the cell
3) Cross wall completely forms
4) cells separate
What are the four types of culutre media?
Enriched non-selective, selective/differential media,
What are some examples of enriched non-selective media?
Growths most organisms. EG: blood agar, buffered peptone water, Bolton’s broth (anaerobic bacteria)
What are biocides?
Anything that can inactivate (not necessarily kill) a microorganism) (EG hydrogen peroxide, alcohol, bleach, heat, radiation, phenols)
WHat is a bacteriostatic biocide?
A biocide that inhibits bacterial growth
What is a bactericidial biocide?
A biocide that kills bacteria
What does sterilization mean?
When a product or surface is rendered free of viable organisms (EG autoclaves)
What does septic, anticeptic or aseptic mean?
Septic: pathogenic microbes in living tissues or associated fluid (typically in the blood)
Antiseptic: a biocide used on living tissue (EG detergent)
Aseptic: microogranism free
MOA to stop microbe growth
Damage DNA, protein denaturation (heat or chemical), membrane disruption, cell wall disruption (EG penicillin)
How to damage microbe DNA?
Ionizing radiation, UV light, DNA reactive chemicals
What are three ways bacteria resist antibacterial agents
Physical barriers (EG Vancomycin), Genetically encoding (beta-lactamase), mutations in binding-sites
What are some physical sterilizating agents?
Heat, radiation
What are the MOAs of chemical agents (5)? Give examples.
1) Damage to DNA: UV, ionizing radiation, DNA-reactive chem
2) protein denaturation: heat or chemical agents
3) cell membrane/wall disruption: active transport or diffusion disruptions, enzyme disruption
4) Free sulfhydryl group (Cys) disruption: penicillin, oxidizing agents can form links, Mercuric ions
5) Chemical antagonism (enzyme interference): carbon monoxide, cyanide (binds to cytochrome C oxidase)
what are the four microscopic examination methods
- Direct examination
- Differential stains
- Acid-fast stains
- Fluorescent stain
What genus is the one with acid-fast bacteria
mycobacteria. Has leperesy and TB. *novocardia has some.
What are two acid-fast stains? what are two fluorescent stains.
-acid fast: Ziehl-Neelsen, Kinyoun stain
-fluorescent: Auramin-rhodamine, acridine orange stain
What are some classic ways to subtype bacteria via biotyping
biotyping = biochem
-sugar fermentation
-amino acid decarboxylation/deamination
-hemolysis
What is the difference between Eubacteria and archaebacteria
Eubacteria = classic bacteria. Possess peptidoglycan layer, membranes, proteins, and DNA+machery
archaebactera = NO classic peptidoglycan cell wall. *
Cell wall lacking eubacteria mycoplasmas exsist
What are three methods used during epidemics to id/subtype a microorganism
-biotyping
-serotyping
-antimicrobial susceptibility testing
what do you call an Eubacteria that lacks a cell-wall ?
mycoplasmas
What are some enriched non-selective media examples?
Blood agar (Nutrient media + blood), buffered peptone water (for bacteria only), Bolton’s broth (anaerobic bacteria)
Whats a selective/differential media? give examples
Selective: only lets some organisms grow
differential : allows to differentiate between two bacteria
-MAC
-Xylose-lysin deoxycholate (XLD)
- Chromagar
What elements are needed for bacteria to grow?
C, O, H, N, S, P, K, Na
-O2 is not required by all bacteria. toxic oxygen can be very rxtive.
What are some toxic oxygen species?
peroxide anion, singlet oxygen, superoxide radicals, hydroxyl radicals
What four things influence enzymatic rxn rate?
temp, pH, concentration, inhibitors if present
What does catalase do?
It deals with toxic oxygen. Means it must be O tolerant
What is the difference between obligate anaerobes and facultative anaerobes? what is the aerobic version of facultative anaerobes
-facultative anaerobes: okay either way. Equivalent is aerotolerant anaerobes
-obligate : need it
Whats an inorganic enzyme?
a catalyst