micro - virus and bacteria Intro Flashcards
Name 4 microbes and their classifications.
Bacteria (prokaryote)Protozoa (eukaryote)Fungi (eukaryote)Viruses (neither pro nor eu)
Bacteria
Prokaryote
Protozoa
eukaryote
Fungi
Eukaryote
Viruses
not prokaryotic or eukaryotic
2 basic shapes of bacteria
ROD (aka Bacillus) -2 together= diplobacilli-chains of bacilli = streptobacilli-other arrangements = palisades (side by side/ “X” “V” or “Y” figures)COCCIlittle circles - can make long beaded strings, clumps, tetrad, cubicles, or diploccoccus
Possible bacteria shapes
-rod-cocci-spirochetes (flexible undulating corkscrew)-spirillum (RIGID corkscrew shape)-diplococci-diplobacilli
bacterial chromosome:
in nucleoid…basically 1 chromosome, tightly packed
Mesosome:
chromosomal DNA attached to the bacterial membrane, invaginated at the site of bacterial division(small dark circular part…as opposed to large white nucleoid…)
Plasmid DNA:
self-replicating unit of DNA distinct from the chromosome - IMPORTANT - much smaller than chrom, but contain very important info like antibiotic resist. genes, etc. (A specific plasmid will make it resistent to specific antibiotic.) Some are mobile - can transfer between bacterium (REMEMBER: sometimes even between diff. bact. species. ALSO remember antibiotic resis. frequently resides in plasmids)
Ribosomes and Granules:
Bacteria have no ribosomes…no endoplasmic reticulum…individual protiens are diffferent from those in Euk. whatever is external is highly antigenic (we make antibodies to it, especially things like flagella)
Flagella:
- used by bacteria for locomotion- composed of flagellin- different arrangements of flagella: (not so important as simple - are they mobile or not)monotrichouslophotrichousamphitrichousperitrichous (multiple flagella)
Flagellar motor:
Mostly know: some bacteria can move with presence of flagella and flagella antingens help diagnose cause of disease and therefore tell what antibiotic to use to treatotherwise, made of protein flagellin, has a filament and a basal region (basal body = rod and rings). Gram+ have 2 rings; gram- have 4 rings.
Pili (fimbriae)
shorter and finer than flagella- 2 types: adherence pili (attach bacteria to surfaces) sex pili (important in bacterial conjugation; found in some gram- bacteria)
Capsule
- slimy outer coating externally produced - not found in all bacteria- usually a complex of high molec. weight polysaccharides- called Slime or Glycocalyx (generally more loosely associated- adherence properties) - think biofilms: some bacteria produce biofilm on replacement knees, hips, etc. - can be antiphagocytic(what bacteria have/produce/can do is dictated by genetic info and by environment)[very important that body recognizes it as forieng…body cells envelop cells and phagocytize them. but the glycoclyx or capsule on some bacteria keeps that from happening]
cytoplasmic membrane
-encloses bacterial cytoplasm-phospholipid bilayer - selectively permeable-embedded with proteins-site of nutrient transport- SITE OF RESPIRATION
peptidoglycan - cell wall
60-90% of gram+ cell wall; much less in gram-UNIQUE COMPONENT OF BACTERIA - THEREFORE USEFUL FOR FIGHTING BACTERIA
cell wall:
structure determines staining properties - use in IDing bacteria
n-acetyl-glucose aminen-acetyl-nuramic acid
NAM and NAG - make up peptidoglycansome have peptide attached to that (unique to individual bacteria)peptide hangs off…there is cross-linking between tetrapeptides
penicillin
inhibits cross-linking between tetrapeptidesso much pressure in cell it lysesso peptidoglycan = extremely important
do all bacteria have NAM and NAG?
yes - different types of tetrapeptides, can be crosslinked by another peptide or directly to one another, depending on species, but cross-linking always occurs.
Gram+ bacteria
have MUCH MORE peptidoglycan in cell walls - much more easy to get things inside gram+ relative to gram-
Gram - Bacteria
much less peptidoglycan; has outer envelope that helps things come in or out; MUCH MORE DIFFICULT to get things in/out of gram- than gram+ especially large structures
gram stain
developed by Hans Christian Gram- Gram+ retain purple iodine-dye complexes after treatment w/decolorizing agent; gram- bacteria do not retain complexes when decolorized - safranin is then used to counterstain the gram-: Chrystal violet comes in, turns all cells blueIodine comes in, forms large complexAlcohol takes away cell membrane/phospholipid molecules (decolorizes gram- but not gram+ so much peptidoglycan in gram+, the crosslinking prevents the complexes that formed from leaving - they are locked in) + stays blue.
Gram+ stain:
purple/blue
Gram- stain:
stain red/pink
Techoic Acid
only found in gram +- water-soluble polymer of ribitol or glycerol residues joined by phosphodiester linkages
Found only in Gram + Cell Wall
Teichoic acids/teichuronic acidslipoteichoic acid (LTA)polysaccharides
Teichuronic Acid
similar to teichoic acid, but made in phosphate-limiting conditionsONLY IN GRAM +
Lipoteichoic Acid (LTA)
lipid attached to Teichoic Acid - ADHESINonly in gram +
polysaccharides
mostly likely composites of sugars released from teichoic and teichuronic acidonly in gram+
endotoxin:
toxic component assoc. only with gram- bacteriabody reactions with endotoxin to cause endotoxic shock - kills peoplefound in outer membrane of gram - bacteria only…lipopolysaccharide in outer membrane is the endotoxin that causes pathogenic effects in bodythings that prevent crosslinking not as effective for gram- : some can’t fit through; and there isn’t as much cross-linking anyway
Found ONLY in gram - cell wall:
-lipoprotiens-periplasmic space-outer membrane-lipopolysaccharide
periplasmic space:
gel-like matrix between cytoplasmic membrane and outer membranecontains enzymes for nutrient breakdown and substrate blinding proteins, including penicillin binding proteins. (penicillin-binding proteins are the ones that do the cross-linking!!)only in gram -
lipoprotein
- cross-links outer membrane to peptioglycan - IN the periplasmic spaceonly in gram -
Outer Membrane
phospholipid bilayer containing lipopolysaccharidescontains porins (non-specific pore proteins) anchor proteins and transport proteinsprotects cell from hydrolytic enzymesonly in gram-
Lipopolysaccharide (LPS)
made of lipid A (complex lipid)covalently attached to a polysaccharide with core and terminal repeat unitsLPS (lipd A) is called ENDOTOXIN. extremely toxilipid portion of LPS is attached to the outer membrane by hydrophobic bondspolysaccharide chain of repeating units is called the -antigen (exposed to outside of cell - is antigenic)only in gram-
O-antigen
exposed to outside of gram- cell, made up of polysaccharides unique to each species of bacteria, part attached to lipid A (constant through bacteria) that sticks out and that that the body responds to
Mycoplasma (and ureaplasma)
smallest free-living organismsNO CELL WALL (no peptidoglycan; bacterial stains don’t work well)only barrier is the cytoplasmic membraneMEMBRANES CONTAIN STEROLS - required for growth (not synthesized by bacterium)
gram +
cell wall
gram -
envelope
Acid Fast Bacteria
-mycobacteria (and nocardia) do have some cell wall contain large amounts of peptidoglycan contain large amounts of glycolipids lipoarabinomannan (LAM) mycolic acids (60% of cell wall) - help make cell walls impermeable make cell walls impermeable
Acid Fast Stain
stain with red carbolfuchsin and destain with acid alcoholOnly acid-fast bacteria will retain stain after decolorizing step
Do Acid Fast Bacteria have cell walls?
yes, have impermeable mycolic acid walls
Do mycoplasma have cell walls?
no! do have sterols in their cell membrane which the others don’t!
Protein Secretion Systems: Gram -
6 classes:play major role in bacteria interacting with environment and helping to determine their pathogenicity
Protein Secretion Systems: Gram +
have 7 classesplay major role in bacteria interacting with environment and helping to determine pathogenicity
Protein Secretion Systems: structure
UNIQUE TO SPECIFIC BACTERIA - VERY IMPORTANT ROLE IN PATHOGENICITYsimple ones like T1SS consist of transporters/outer membrane factors/membrane fusion proteinsothers (T3SS, T4SS, T6SS) involve injectisome - transmembrane structure which consists of more than 25 proteins
protein secretion system - function
transport proteins or nucleic acids (T4SS) to outside of cell, periplasm, or inside host cellstransported proteins can be surface proteins like adhesins or toxins which modify host cell physiology causing pathological consequencesKNOW IF SPECIFIC SPECIES HAS IT OR NOT - will be important
Endospores
made by Bacillus and Clostridium species in nutrient-limiting conditions (starvation) highly resistant to heat, desiccation and chemical damage able to resist heat because of dehydration Calcium dipicolinate in the core (5-15% of spore’s dry weight)
spores form by:
signaling, spore septum forms, stuff happens
Spore wall:
contain normal peptidoglycan; will be cell wall of germinating bacterium
spore coat:
contains keratin-like proteins, very impermeable to chemicals
cortex
thickest part of spore envelope - contains peptidoglycan with fewer cross-links
Core
contains the calcium dipicolinate and all nucleic acid for later growth
do all bacteria form spores?
no, must have the genes to do so
What are the 2 types of viruses?
prokaryotic viruses = bacteriophage (not so important…sometimes bacteria susceptibility to virus’s is used to ID certain kinds of bacteria…some kind don’t lyse the cell, just give new info to bacteria that contributes to pathology)eukaryotic viruses, animal viruses
what do viruses do?
Sit on outside and inject nucleic acids into cell
thing to remember about viruses!
they are obligate intracellular parasites - main function is to replicate and need a host to do so
general characteristics of viruses:
viral particle is DNA or RNA in a protein coat with or without a membraneouter coat protects genetic material and facilitates adhesion/infectioncontains very few enzymes, no organelles or other biosynthetic machinery (no ribosomes)nucleic acids for proteins needed for viral replication
Enveloped Viruses:
acquire membrane from host
Naked Capsid Viruses:
Protects nucleic acids(RNA or DNA) with coat or capsid
Capsomere
subunit of the capsid structure
Different capsid structures:
polyhedralhelical
viroids:
Very small SS circle of RNA (300-400 nucleotides)cause disease in PLANTSreplication strategy unknown - probably thru host RNA polymeraseHDV is similar to viroid
What causes slow virus disease?
PRIONS (cause Scrapie, Kuru, Creutzfeldt-Jakob disease, and mad cow disease (BSE - very real, serious problem is vCJD - caused by variant of Creutzefeldt-Jakob - a variant of that can cause a similar human disease) - subacute spongiform encephalopathies)
Prions…
resistant to heat inactivation (autoclaving), radiation damage, and nucleases (DNAses and RNAses…contain no nucleic Acid!)can be inactivated by detergents, urea, phenol, etccausative agent is prion protein: PfPsc
What is PrPsc
normal human protein (PrPc) that folds differently, causes nearby proteins to fold differently - normally folded (alpha helices) gets degraded by proteases, abnormally (beta sheets) isn’t degraded, causes disease
Fungi
- Eukaryotic-require preformed organic compounds for growth; some don’t
What is dominant membrane sterol in fungi?
Ergosterol, rather than cholesterol
Do fungi have cell walls?
yes
What are the 3 types of Fungi?
yeastsmoldsmushrooms(some of former two cause disease)
What are yeasts and how do they reproduce?
single cell fungireproduce by budding (blastoconidia)some strains (Candida) produce pseudohyphae
What are septae?
cross walls of hyphae (filamentous forms of mold) produced by many mold species
how do molds grow?
in filmentous forms called hyphae
Do nonseptate hyphae exist?
yes
what are masses of hyphae called?
mycelia
Dimorphic Fungi
exist as yeast or yeast-like form AND filamentous form
Dimorphic fungi exist as yeast or yeast-like form AND filamentous form - what controls form?
environmental conditions like temp and nutrients
Dimorphic fungi exist as yeast or yeast-like form AND filamentous form - which is where?
yeast form found in body/filamentous form (that infects) is found in environment
Fungi: Spores
of diagnostic value for IDing fungi- conidia (asexual spores of molds)- arthroconidia (formed from joints in hyphae then fragmentation)
What are protozoa?
single cell parasites
2 forms of protozo:
trophozoites (motile form) - move by flagella or ciliacysts (resting stage)
3 types of worms:
trematodes (flukes)cestodes (tapeworm)nematodes (roundworms)
what does worm infection usually involve?
ingestion of larval or cyst forms
what is bacterial replication?
generation of 2 complete daughter cells from 1 cell
steps of binary fission in bacteria multiplication:
-replication of DNA-polar separation of daughter chromosomes-generation of the cross-wall-separation
What is generation time?
time it takes for one cell to become two - the amount of time required for # of cells in a culture to double (each cell to become two)
doubling time:
generation time
two types of antimicrobials:
STATIC - stop multiplication of bacteria (does’t kill, but stops growth until immune system can come in and kill it)CYTOL- ?? not yet important…
Are all descendants of a single cell clones?
yes, they’re copies
Most replication is synchronous or asynchronous?
Asynchronous
how are cell #s measured?
by cell concentration or biomass
What is growth curve?
bacterial counts of fresh media inoculated by a saturated broth culture are taken at different time points and plotted as cell number versus time
Phases of growth curve
Lag phase: bacteria adapt to new nutrient-rich environment (changing from long generation time to short generation time)Log Phase (logarithmic growth) Bacteria doubling every generation time, new cell material is synthesized at a constant rateStationary Phase - nutrients are exhausted; toxic products begin to build up. Bacteria remain at a relatively constant #Death Phase - bacteria begin to die because of toxicity. Not all bacteria have a death phase
How do you find bacterial concentration?
dilute culture 10-FOLDplate known volume of liquid onto growth mediaallow colonies to grow then count them (each colony represents 1 bacterium from original culture)calculate original concentration (at time of sampling)ONLY REPRESENTS VIABLE BACTERIA~ make
What is required for bacterial growth?
all elements for organic matter (esp. a carbon source!)ions for energy generation, catalysis, and osmotic maintenance(depends on genetic makeup, tho - some can synthesize almost everything…but if in nutrient rich environment, won’t bother to synthesize them)
What are the three energy sources for bacterial cultivation?
fermentationrespirationphotosynthesis (ATP is formed via reduction of an oxidant via light energy. similar to respiration)
what is fermentation?
formation of ATP not coupled to electron transfer (anaerobic bacteria use it- O2 kills them)
what is respiration?
formation of ATP vi oxidative phosphorylation (chemical reduction of an oxidant) wherein ATP is formed during e- transfer
What do you get out of fermentation? Is final hydrogen accepter organic or inorganic?
2 ATP + acids, alcohols, etc (incomplete breakdown products) Organic
Nutritional requirements for bacterial cultivation:
C, N, S, Phosphorus, Ca, Mg, K, Fe, and other minerals in mall amounts There are exceptions for Feanything bacterium need but cannot make must be provided or obtained from host
What is a heterotroph
requires pre-formed organic compounds Iike sugars, AAs, and vitamins
what is an autotroph
cna synthesize everything it needs from inorganic compounds like CO2
What is a hypertroph?
obligate intracellular pathogen that requires host to provide organic compounds (basically an intracellular heterotroph)
How do bacteria get nutrients?
diffusion thru cytoplasmic membrane-permeases = specific carrier proteins that help with uptake of nutrients
What are the 5 basic types of Bacteria and how are they classified?
By oxygen requirements-obligate aerobesobligate anaerobesfacultative anaerobesmicroaerophilicaerotolerant anaerobes
What kind of bacteria must have O2 for growth?
obligate aerobes
what kind of organisms are killed by oxygen radicals generated during metabolism of O2
Obligate anaerobes
which kind of bacteria can grow w/ or w/out O2
facultative anaerobes
which kind of bacteria must grow at concentrations of O2 less that 20%
microaerophilic
what are aerotolerant anaerobes?
similar to facultative anaerobes, but prefer anaerobic (fermentive) growth
What does superoxide dismutase do?
converts oxygen radical to oxygen and hydrogen peroxide
What are the 3 diff. classifications of bacteria optimal growth temp?
Psychrophiles (0-20C)Mesophiles (20-45C) (most kinds we’re concerned with)Thermophiles (45-90)
Bacterial growth media must include:
- basic requirements for the bacteria needed to growNOTE: “defined media” is made with chemicals at known concentrations.
What is differential media?
supplies nutrients and indicators for VISUAL DETERMINATION of which organisms are present
What is Selective Media?
selects AGAINST the growth of a particular bacteria by addition of dyes. acid/base, salts, or antibiotics
