Principles of Micro 2 Flashcards
describe the experiment by Louis Pasteur
he did the experiment with the swan neck flask where he boiled broth to get rid of all the microorganism and it stayed sterile because microorganism were trapped in the neck of the flask
what happened to the broth when the neck of the flask was broken
it became contaminated once exposed to the air
describe the work of Robert Koch
he wanted to figure out how disease occurred using pure culture from a diseased mice and infecting a healthy mice
what are Koch’s postulates
- the suspected causative organisms should always be present with the specific disease and absent in healthy animals
- the suspected organism can be grown in pure culture
- organisms taken from pure culture should cause disease in healthy animal
- the suspected organism can be re-isolated and shown to be the same as the original
what were problems with Koch’s postualtes
- not all microorganisms are culturable
- some microorganisms are opportunistic - so they can be present in a healthy individual and not cause disease unless under the right conditions
- re-isolated microorganisms might not be the same as original
who is John Snow
- father of epidemiology
- showed contaminated pump handles were contaminating water causing cholera
who is Edward Jenner
- he inoculated a young boy with cowpox to create immunity against smallpox
- brought about the concept of vaccination
what is Ignaz Semmelweiss known for
washing hands between patients can reduce incidence of infections (though his idiot companions paid him no mind)
describe the work of Anthon von Leeuwenhoek
he came up with the early microscope
what is magnification, resolution, and resolving power
magnification - enlarging of object
resolution - degree to which detail is maintained in object
resolving power - minimum spacing between two points where can be clearly as separate entities
factors the limit microscopic magnification of microorganisms
resolution, resolving power, wavelength
light source and max magnification for brightfield
visible
1500x
light source and max magnification for fluorescence
UV
1500x
light source and max magnification for TEM
electrons
500,000 - 1,000,000 x
light source and max magnification for SEM
electrons
10,000 - 1,000,000x
what are two different ways to prep specimen for microscopic viewing
- placing live specimen on surface then putting a coverslip
- kill specimen then put coverslip
for both preparation one can put dye or stain
when will one use a live vs. killed specimen
live: motility, cell behavior, short term
killed: physical appearance, longer term storage
what does the positive stain stick to
- the actual specimen providing color
- basic (neg aspect)
what does the negative stain stick to
- settles around the specimen to form a silhouette so sticks to the background
- acidic (positive)
what color does the gram positive and gram negative stain
gram + - purple
gram neg - pink
when does one gram stains
for some bacterias but it can’t stain all
what is Paul Ehrlich known for?
the stain method called acid fast - ziehl neelsen method
how does the acid fast-ziehl neelsen method work
carbol fuschin –> heat five mins –> decolourise –> methylene blue
what are the colors of the stain in acid fast-ziehl neelsen method
the acid-fast bacteria stains pink/red
while the non-acid fast bacteria stains blue
what species uses acid fast-ziehl neelsen method and why?
mycobacterium sp because of its waxy outer coat
how does the fungal stain work
skin scraping –> 10% KOH –> heat gently –> keratin dissolves –> fungi visible
do prokaryotes have cell wall
yes except in mycoplasma sp
nuclear membrane and nucleolus is present in what?
eukaryotes but def not in prokaryote or viruses
difference in ribosomes between prokaryotes, eukaryotes, and viruses
prokaryotes - small 70S (30 and 50)
eukaryotes - large 80S (40 and 60)
virus - absent
what type of DNA do plasmids have
circular DNA
how does bacteria genome differ from fungi and viruses
- they are mainly circular with the exception of one
- smaller in size
- single chromosome with no associated proteins
what separates the surface structures from the internal structures in bacteria?
cell wall – also keeps cells rigid
importance of capsule
helps to temporarily escape phagocytosis
prevent bacteriophage attachment
importance of fimbriae/common pili
help attach to surfaces or tissue
help bacteria attach to each other for urinary system
importance of flagellae
for motility
different between gram positive and gram negative surface structure
gram positive - cytoplasmic membrane and peptidoglycan
gram negative - cytoplasmic membrane, peptidoglycan, and outer membrane
difference in peptidoglycan between gram positive and gram negative
gram negative has a thinner peptidoglycan layer
what does gram positive have that gram negative does not
techoic acid and lipotechoic acid
importance of cell wall in bacteria when it comes to antibiotic treatment
cell wall of bacteria is made up of peptidoglycan only found in bacteria so can be used as a unique target for antibiotics
other than antibiotic factor, what is the importance of cell wall in bacteria
contributes to symptoms of disease
defines cell shape
maintains osmotic integrity
