layers of peptidoglycan connected by
NAM-NAM linkages between 3rd AA and 4th AA (D-ala)
peptidoglycan single layer consists of
alternating nam and nag units
PBP
penicillan binding proteins - transpeptidases and carboxypeptidases
transpeptidases
catalyze formation of NAM-NAM cross link
carboxypeptidases
clease the fifth D-ala and produce ATP during formation of the NAM-NAM cross link
S layer
highly organized layer of protein and glycoprotein present in archael species - binding and attacking host cells, biofilm formation
slime layer
easily removable layer for protection and adherance
magnetosomes
organelle containing mineral magnetite - for sensation of magnetic field
PHB and PHA
polymers from storage granules for phototrophs to use in low light conditions
carboxysomes
protein-enclosed compartment containing rubisco to fix carbon dioxide
stalk
extension of cytoplasm and envelope to attach to a substrate
nanotubules
extension of cell envelopes that connect cytoplasm or periplasm of different cells
B lactam drugs
bind to PBPs and inhibit them to prevent synthesis of new cell wall
how do bacteria fight against B lactam drugs
B lacatmases
vancomycin
not a B lactam drug but works in same space - prevents fifth D-ala from leaving so cross link cannot form
gram positive phylum
firmicutes
gram negative phylum
proteobacteria
firmicute peptidoglycan contains
techoic acid to give it negative charge
organization of proteobacteria cell wall
outer membrane (LPS then lipoprotein) thin peptidoglycan layer, inner membrane (plasma)
LPS
lipopolysaccharide - endotoxin released upon cell death O antigen, core, lipid A tail
archael cell wall structure
NAG-NAT pseudopeptidoglycan, S layer
why are archaea resistant to b lactam drugs and lysozyme
no nam-nam linkages (b lactam) no nam-nag linkages (lysozyme)
stages of gram staining
crystal violet - purple gets between peptidoglycan layers; iodine (mordant) - forms complex; alcohol - washes away complex and dissolves outer membrane; safranin - dies gram negative pink
acid fast staining
used for mycobacterium - steam melts waxy mycolic acid - then dye - cools, wax solidifies and traps dye - won’t wash away, indicates mycobacterium
spore stain
malachite green to detect spores (bacillus and clostridium)
negative stain
has negative charge to repel negative charge of cell wall - visualizes capsule
phototroph
uses light as source of energy
chemotroph
uses organic or inorganic compound as source of energy (not carbondioxide)
lithotrophs
electron source is inorganic molecule (hydrogen gas, sulfur)
organotroph
electron source is organic molecule
heterotroph
carbon source is preformed organic molecule
autotroph
use carbon dioxide as primary carbon source
ABC transporter
solute binding proteins bind to solute that needs entering - complex binds to ABC transporter, ATP used to open transport protein
siderophores
binds free iron to transport into bacterial cells
group translocation
chemically alters substrate during transport to hack gradient
PTS
phototransferase system, uses energy from PEP byproduct to attach phosphate to sugars during group translocation
SOD
superoxide dismutase to neutralize superoxide anion (present in obligate aerobes, facultative anaerobes, aerotolerant and microaerophiles)
catalase
breakdown of hydrogen peroxide (present in obligate aerobes, facultative anaerobes, maybe in microaerophiles)
blood agar
red, enriched; differential for hemolysis
differentiation on blood agar
no color change - gamma, normal growth;
green - alpha, partial hemolysis;
white - beta, complete hemolysis
EMB agar
selective for gram negative, differential for ability to ferment lactose
differentiaion on EMB agar
determine by acidification;
clear - no fermentation;
pink - some fermentation
green - lots of fermentation (e coli)
mannitol salt agar
pink agar selective for halophiles, gram positive; differential for fermentation of mannitol (generally used for staph)
differentiation on mannitol salt agar
pink - no fermentation;
yellow - fermentation
citrate agar
green agar selective for gram negative, differential for citrate as carbon source
differentiation on citrate agar
green - can’t use citrate;
blue - can use citrate
SIM agar
sulfure reduction, indole production, motility
appearance on SIM agar
black precipitation for sulfur reduction;
red ring for indole;
turbid throughout for motility