Module 8 Flashcards
Bacteria gone wild
What size are microbes?
1 mm or smaller diameter
What are some examples of microbes?
metazoan animals, protozoa, algae and fungi, bacteria, and viruses
Who disproved theory of spontaneous generation through maggots?
Francesco Reddi
Which two scientists established Microbiology as a Science?
Pasteur and Koch
Who proved germ theory and discovered the rabies vaccine?
Pasteur
Who discovered phagocytosis?
Metschnikoff
List Koch’s postulates
pathogens are found in cases of disease but not in healthy animals. Pathogens can be isolated and grown in culture. Cultured pathogen must cause disease when inoculated into an animal. Pathogen can be re-isolated from the inoculated animal and is the same pathogen
What are some of the exceptions to Koch’s postulates about culturing?
Treponema pallidum and Mycobacterium leprae (and some other rickettsial and viral pathogens)
3 major classes of microbes
viruses, prokaryotes, and eukaryotes
4 prokaryotic microbes
bacteria, mycoplasmas, rickettsiae, chlamydiae
3 eukaryotic microbes
fungi, protozoans, and multicellular parasites
average onset age of CJD
68 years
average onset age of vCJD
28 years
Smallest and simplest of all microbes
viruses
what microbe is composed of DNA or RNA and a protein coat (and sometimes a lipoprotein envelope)
viruses
Which microbe is an obligate intracellular parasite?
viruses
unicellular organisms that do not have clearly defined nuclear membranes
prokaryotes
uni- and multicellular organisms with well defined nuclear membranes
eukaryotes
which microbe has nucleic acids and histones arranged into chromosomes?
eukaryotes
What comprises a fungal cell wall?
chitin, glucans, and mannans
What fungi have ergosterol in their membrane?
yeasts, filamentous molds (like mycelia), dimorphic fungi, and saphrophytes which use organic matter for energy
Eukaryotic organism that lives in or on another host and causes damage, and can be anything from a single cell to large multicellular worms
parasites
How are bacteria grouped?
based on morphological and biochemical/metabolic differences and immunologic and genetic characteristics
Order and chemicals used for a Gram stain
crystal violet (primary stain), iodine (mordant), alcohol (decolorizer), safranin (counter stain)
What color do gram positive bacteria stain?
purple
What color do gram negative bacteria stain?
pink
molecules of N-acetyl glucosamine that alternate with N-acetyl muramic acid
peptidoglycan
Which bacteria have a large peptidoglycan layer in the cell membrane?
gram positive
Which bacteria have an inner and outer membrane?
gram negative
enzyme that catalyzes the formation of pentaglycine cross bridges in peptidoglycan
transpeptidase (aka penicillin binding protein)
Which bacteria have techoic acids?
gram positive
water soluble polyol phosphate polymers with either ribitol or glycerol linked with phosphodiester bonds
teichoic acids
2 classes of teichoic acids
lipoteichoic and wall teichoic
What function do teichoic acids serve?
bind and regulate movement of cations, provide antigen specificity, and may prevent lysis during growth
which type of bacteria contains lipopolysaccharide (LPS)?
gram negative
What two things make up the LPS?
O antigen and Lipid A
What part of LPS is responsible for toxicity in gram-neg endotoxins?
Lipid A
what are some examples of surface specific proteins?
m-protein, tuberculin, and a-protein
What helps gram positive bacteria attach to human cells?
teichoic acids, pili, and virulence factors
What are the 2 layers of the gram positive envelope/membrane?
thick peptidoglycan layer and cytoplasmic membrane
What are the 3 layers of the gram negative envelope/membrane?
outer membrane, thin peptidoglycan, and inner membrane
major triggers of inflammation on gram positive bacteria?
teichoic acids in peptidoglycan
Which type of bacteria are more susceptible to lysozyme and beta lactam drugs?
gram positive
major triggers of inflammation on gram negative bacteria?
endotoxins
What drug inhibits bacterial cell wall synthesis?
beta lactam
How do bacteria become beta lactam resistant?
by expressing beta lactamases
What drug binds irreversibly to beta-lactamases?
augmentin (amoxicillin and clavulanic acid)
What allows gram negative bacteria to get beta-lactam resistance?
secondary beta lactam resistance through mutations in penicillin binding proteins (PBP), chromosomal class C-beta-lactamase, and extended spectrum beta-lactamase (ESBL) and TEM beta-lactamase
What is the full name for acid fast staining?
Ziehl-Neelsen acid fast stain
What reagents are used in acid fast staining?
carbol fuschin (with heat), acid alcohol, and methylene blue
What color do acid fast bacteria stain?
red/hot pink
What color do non-acid-fast bacteria stain?
blue
Acid fast staining of mycobacterium
acid fast
Acid fast staining of Nocardia
partially acid fast
Acid fast staining of Legionella micdadei
weakly acid fast
Organisms that require oxygen for growth at atmospheric levels, and don’t do fermentation
obligate aerobes
Which organisms produce superoxide dismutase?
obligate aerobes
Pseudomonas, M. tuberculosis, and Bacillus are: facultative anaerobes, microaerophiles, or obligate aerobes?
obligate aerobes
Organisms that require oxygen for growth but at lower than atmospheric level
microaerophiles
Campylobacter and Helicobacter are: facultative aerobes, microaerophiles, or obligate aerobes?
microaerophiles
Organisms that use oxygen if it’s present but don’t need it to survive
facultative aerobes(also called facultative anaerobes!!!)
Streptococci and Enterobacter are: facultative aerobes, microaerophiles, or obligate aerobes?
facultative anaerobes
Organisms that grow in the presence of oxygen but can’t use it
aerotolerant anaerobes
Streptococcus is an example of: obligate anaerobes, aerotolerant anaerobes, or facultative anaerobes
aerotolerant anaerobes
Organisms that cannot grow in the presence of oxygen and only use fermentation pathways
obligate anaerobes
Actinomyces, Bacteroides, and Clostridium are: obligate anaerobes, aerotolerant anaerobes, or facultative anaerobes?
obligate anaerobes
3 components of flagella
basal body, hook, filament
part of the flagellum that spans the entire cell wall and consists of a small central rod inserted in a series of rings that spin around to spin the flagellum
basal body
single flagellum (like Pseudomonas)
monotrichous
two flagella (like Spirillum)
amphitrichous
two or more flagella at one or both ends (also Spirillum)
lophotrichous
flagella all over the surface (like Salmonella or Proteus)
peritrichous
what bacterial structure can serve as adherence factors/adhesins?
pili(fimbriae)
difference between pili and flagella
pili are much shorter and non motile
2 kinds of pili
attachment and conjugation
How does Neisseria gonorroheae use its pili?
it binds to cervical and buccal cells to cause gonorrhea
How do E. coli and Campylobacter jejuni use their pili
use adhesins to bind to intestinal epithelium to cause diarrhea
polysaccharides that form the outermost layer attached to bacterial cell wall
capsules
what enables bacteria to be more virulent by stopping neutrophils and macrophages from phagocytosis
capsules
What’s an example of a bacteria with a capsule?
Strep pneumoniae
2 tests for visualizing capsules
india ink stain and quellung reaction
Which 2 genera of gram positive bacteria form endospores?
Bacillus (aerobic) and Clostridium (anaerobic)
extracellular polysaccharide network that forms a mechanical scaffold around bacteria
biofilm
proteins released by both gram positive and negative bacteria
exotoxins
what are some gram negative bacteria that release exotoxins?
Vibrio cholerae, E. coli
What are types of exotoxins?
neurotoxins, enterotoxins, pyrogenic exotoxins, tissue invasive exotoxins, miscellaneous exotoxins
Clostridium tetani and botulinum release what kind of exotoxin?
neurotoxin
2 disease manifestations of enterotoxins
infectious diarrhea (like with cholera) and food poisoning (like with bacillus cereus or staph aureus)
exotoxin that stimulates the release of cytokines and can cause rash, fever, and toxic shock syndrome
pyrogenic exotoxins
Staph aureus and Strep pyogenes can release which type of exotoxin?
pyrogenic exotoxins
class of toxins that binds to receptors on target host cells, but isn’t internalized within the cell
type I toxins
TSST-1 of Staph aureus is an example of what class of toxins?
type I toxins
class of toxins that mechanistically destabilizes host cell plasma membranes
type II toxins
class of toxins that binds to the surface of target host cells and some becomes internalized within the cell (like cholera toxin)
type III toxins (A-B toxins)
toxin released when bacteria undergoes lysis
Lipid A/endotoxin
which class of bacteria releases endotoxins?
gram negative
endogenous mediator of sepsis
TNF
What treatments seem to help septic shock?
antibiotics ofc, recombinant activated protein C (drotrecogin alpha), hydrocortisone, polyclonal IVIG
which species of bacteria have linear chromosomes
Borrelia and Streptomyces
does bacterial dna have histones or a nuclear membrane?
neither
is bacterial dna ss or dsdna
dsDNA
supercoiled, circular, double stranded extrachromosomal pieces of DNA that replicate independently of the chromosome
bacterial plasmid DNA
3 functions of bacterial plasmid DNA
pathogenicity, produce toxins, synthesize cell structure for adherence and colonization
3 types of plasmids
fertility/conjugative plasmid (F plasmid), drug resistance factors (R plasmid), and Col plasmids
phage DNA that arises through infection with a temeprate phage whose viral production is repressed
stable phage DNA
uptake of extracellular DNA by bacteria from the environment
transformation
Generalized or specialized transfer of DNA mediated by bacteriophages
transduction
transfer of DNA by direct donor-recipient contact
conjugation
Naturally transformable bacteria take up DNA from where?
the surrounding environment
What kind of transformation do Bacillus subtilis, Haemophilus influenzae, Neisseria gonorrheae, Streptococcus pneumoniae, and Synechococcus have?
they’re naturally transformable bacteria
what does the transformation protein complex of B. subtilis and Strep pneumoniae contain?
a labile competence factor, a specific endonuclease, DNA-binding polypeptides, and an autolysin to increase cell permeability
4 stages of bacterial growth
lag phase, log phase, stationary phase, decline/death phase
when do naturally transformable bacteria become competent?
late in the growth cycle
regulation of gene expression in response to fluctuations in cell-population density
quorum sensing
how is bacterial competence regulated?
2 component regulatory system based on quorum sensing
small peptides excreted by bacteria as they multiply
competence pheromones
2 components of Bacillus subtilis competence regulation
ComP (histidine kinase sensor) and ComA (response regulator)
Which regulatory protein is a histidine kinase sensor?
ComP
Which regulatory protein is a response regulator?
ComA
What are 2 species of bacteria that take up DNA from the same species?
N. gonorrheae and H. influenzae
subcellular compartments that allow H. influenzae to take up dsDNA
transformasomes
Why do bacteria have natural competence?
for diversity, repair, and nutrition
introduction of multiple copies of the same plasmid DNA into a single cell can regenerate what?
an intact plasmid
What are 2 types of artificially induced competence?
chemical transformation and electroporation
what type of induced competence is found when bacterial cells w/ DNA are pulsed with electric current?
electroporation
What type of induced competence is found when bacteria are exposed to calcium ions and undergo heat shock treatment?
chemical transformation
Which type of transformation prefers hot environments and which prefers cold?
chemical transformation is with heat and electroporation is cold
type of transduction where any region of the bacterial DNA can be transferred
generalized transduction
type of transduction where certain genes close to the attachment site of a lysogenic phage in the chromosome is transferred
specialized transduction
phages capable of transduction
transducing phages
original bacterial strain in which the transducing phage is multiplied
donor strain
infected bacterial strain
recipient strain
cells that have rec’d DNA from another bacterium by transduction
Transductants
what makes a good transducing phage?
doesn’t degrade host DNA completely and has nonspecific pac sites
generalized transducing phages carry what genes?
only bacterial genes
specialized transducing phages carry what genes?
bacterial AND phage DNA
direction of conjugation transfer
unidirectional
in what 2 ways does conjugation differ from transformation?
requires direct cell-cell contact and cells must be opposite mating types
recipient cell during conjugation
transconjugant
most naturally occurring plasmids are one of 2 things:
self transmissible or mobilizable
Researchers who performed the U-tube experiment
Lederberg and Tatum
cell with a free fertility factor
F+ cell
cell with a fertility factor inserted into the bacterial chromosome
Hfr cell
cell without fertility factors
F- cells
what controls replication of the F plasmid?
it controls its own replication
F plasmid origins of replication
oriV and oriS
F plasmid origin for bidirectional replication
oriV
F plasmid origin for unidirectional replication
oriS
origin of transfer which proceeds via a rolling circle mechanism
oriT
genes responsible for coding endonucleases nicking the oriT
tra genes
products of tra genes can act on plasmids in what cell?
the same cell
appendage that brings 2 cells together for mating
sex pilus
product of tra genes that makes up the sex pilus
pilin protein
what transports pilin through cell membranes and assembles it on the cell surface?
tra genes
what determines the structure of a sex pilus?
the type of self transmissible plasmid
how long do naturally occurring plasmids transfer with high efficiency
not very long at all
what represses tra genes?
tra genes are repressed when pilin is not synthesized along with other tra gene products
what is the purpose of regulating tra genes?
prevent infection by some phages
What makes an Hfr (high frequency of recombination) cell?
when an F factor is integrated into an F+ cell
What makes a recombinant F- cell?
when an Hfr cell passes some of the chromosome into an F- cell
modified F plasmid from a regular F plasmid that has been cut incorrectly
F’ factors
What were the first cloning vectors?
F’ factors
what have been used to map the E. coli chromosome?
F’ factors
are F’ factors fertile?
yes
