Micro Basics Flashcards
Gram positive
look blue with crystal violet stain
Gram negative
look red from crystal violet stain and instead absorb safranin from the counterstain
Gram positive layers
2 layers: inner cytoplasmic membrane, outer peptidoglycan layer thick with extensive AA cross-linking
outer cell wall with complex cross-linked proteoglycan, teichoic acid, polysaccharides, and other proteins
Gram positive is missing…
NO endotoxin
NO periplasmic space
NO porin channel
Gram positive high or low lipid content?
Low
What kind of attacks are gram positive vulnerable to?
lysozyme and penicillin
Gram negative layers
3
inner cytoplasmic membrane
thin peptidoglycan layer with minimal AA cross linking
outer membrane with LPS
Gram negative high or low lipid content?
High
What do gram negative organisms have that gram positive ones do not?
endotoxin-LPS
periplasmic space
porin proteins
Gram negative LPS layers
outer: specific side chain (made of oligosaccharides) that are useful for Ags for the immune system to respond to
water soluble core polysaccharide
lipid A that is toxic to humans as the gram negative endotoxin; released as our immune system lyses the cells and allows it to be released
What kind of attacks are gram negative organisms resistant to?
lysozyme and penicillin
opposite of gram positive which is vulnerable to these attacks
Clinical relevance of the difference between gram +/-
gram + cell membranes have the ability to allow low molecular weight substances through like dyes and antibiotics, while the gram - does not, making them more resistant
4 main shapes of bacteria
cocci
bacilli
spiral forms
pleomorphic
Cocci
spherical
Bacilli
Rods
short rods are coccobacilli
Spiral forms
comma shaped, S-shaped, or spiral shaped
Pleomorphic
lacking a distinct shape (like jello)
7 classic gram positive bugs in humans
Streptococcus Enterococcus Staphylococcus Bacillus Clostridium Corynebacterium Listeria
Gram positive cocci in humans
Form strips–>streptococcus, enterococcus
form clusters–>staphylococcus
Gram positive rods in humans
produce spores–>bacillus, clostridium
no spores–>corynebacterium, listeria
Gram negative cocci in humans
diplococcic
Neisseria
Moraxella
Gram negative spiral shaped in humans
treponema
sorrelia
leptospira
Other gram negatives in humans
rods or pleomorphic
Mycobacteria
weakly gram +, stain better with acid fast
Spirochetes
have a gram - cell wall, too small to be seen on light microscope, better with dark field
have a few exposed membrane proteins and hidden internal periplasmic flagella
Mycoplasma
no cell wall, only cell membrane so are neither gram - or +
Bacterial DNA
circular and can send out small circles called plasmids
Prokaryotic ribosomes
70S with a 50S and 30S subunit
Eukaryotic ribosomes
80S
Obligate aerobes
use all of the same O2 energy gaining mechanisms that humans use
possess catalase, SOD, and peroxidase
Facultative anaerobes
prefer to use O2 like humans, but can also go to fermentation if need be to live
possess catalase and SOD
Microaerophilic
use only fermentation and can only survive a little O2 with the help of SOD
Obligate anaerobes
have no defense against O2
Catalase
allows for H2O2 to be broken down to water and O2
All staph related to Catalse
catalase positive
All strep related to Catalase
catalase negative
Gram positive facultative aerobes
bacillus cereus
Gram positive facultative anaerobes
staph
bacillus antracis
cornyebacterium
listeria
Gram positive microaerophilic
enterococcus
strep (some are facultative)
Gram positive obligate aerobes
clostridium
prefer puncture wounds
Gram negative obligate aerobes
Neisseria pseudomonas bordetella legionella brucella
Gram - facultative anaerobes
most other gram - rods
Gram - microaerophilic
spirochetes–>treponema, borrelia, leptospira
campylobacter
Gram - obligate anaerobes
bacteroides
