Exam 1- Week 3 (some) Flashcards
-viscous (sticky) , gelatinous polymer that is external to the cell wall
-composed of polysaccharide, polypeptide, or both
-made inside cell and secreted to surface
-doesn’t give strength- gives disease causing ability
Glycocalyx and S-Layers
glycocalyx = sugar coat
-organized and firmly attached to peptidoglycan cell wall
-protective advantages: resistant to phagocytosis and protects from desiccation
capsules
-unorganized, loosely attached to the cell wall
-may facilitate mobility
-porous
slime layers
causes dental caries
streptococcus mutans
mesh-like polymer of identical subunits forming long strands, gives strength and shape to cell
cell wall
two alternating sugars of the cell wall that form the carbohydrate backbone
N-acetylglucosamine (NAG)
N-acetylmuramic acid (NAM)
L-alanine, D-alanine, D-glutamic acid, and either L-lysine or diaminopimelic acid (DAP)
-attached to NAG and NAM
alternating D- and L- amino acids in cell wall
4 amino acids
tetrapeptide
lexorotation
-more common- protein synthesis
L form of amino acids in cell wall
dextrorotation
-only in cell wall = good target for antibiotics
-different structure but mirror image of L-form
D form of amino acids in cell wall
-linear, double stranded DNA virus
-replicates in the cytoplasm
-dumbbell shape DNA core
-globally eradicated
small pox
-first successful vaccine developed- created by Edward Jenner in 1796
-milkmaids who previously had cowpox did not get small pox = immunity
small pox vaccine
acute contagious disease caused by the variola virus, genus orthopoxvirus
small pox
variola major and variola minor
two major forms of small pox
strict specificity for humans
characteristic feature of small pox
-direct and prolonged face-to-face contact
-infectious droplets
-contaminated bedding or clothing
transmission modes of small pox
from when first sores appear in the mouth and throat and the early rash stage
small pox patients become contagious
until last small pox scab falls off
small pox patients remain contagious
contain the variola virus
scabs and fluid found in patients disgnostic sores
incubation period of small pox (longer than others in same genus)
7-19 days
fever, head and body aches, sometimes vomiting
initial symptoms of small pox
most contagious part of small pox, lasts about 4 days
small pox early rash
contagious part of small pox lasting about 10 days
postular rash and scabs
still contagious for small pox lasting about 6 days
small pox scabs fall off
four weeks after rash appears, patient is no longer contagious
no scabs left from small pox
no vaccine or immunization for this disease- has been wiped out
small pox vaccination
cleaves glycosidic bond between NAG and NAM
lysozyme
-strengthens cell wall
-formed from alternating NAG and NAM
-formation is blocked by penicillin
peptide cross-bridge
-gram-negative bacteria, cross-link forms fro amino group of DAP of one glycan strand to the carboxyl group of terminal d-alanine on adjacent glycan strand
-direct formation of peptidoglycan
no inter bridge is present
-gram-positive bacteria
-cross-link amino acids vary between species
-indirect binding of peptidoglycan
short peptide inter bridge present
why gram-positive bacteria are vulnerable to lysis
lysozyme are particularly active on the major cell wall components of this type of bacteria
composed primarily of peptidoglycan and teichoic acids (negatively charged)
gram-positive cell walls
-consist of an alcohol and phosphate
-help maintain cell envelope in gram-positive cell wall
-protect the cell from environmental substances
-may bind to host cells to initiate infection
teichoic acids (negatively charged)
gives the negative charge of teichoic acids
phosphate
additional layer in gram-negative cells
outer membrane
outer leaflet of the outer membrane of a gram-negative cell; lipid A and polysaccharide chains
lipopolysaccharide (LPS)
lipid A buried in outer membrane, core polysaccharide joined to lipid A, O side chain (O antigen) extending outward from core
three parts of the lipopolysaccharide
-contributes to negative charge on cell surface
-helps stabilize outer membrane structure
-creates permeability barrier
-host defense protection
-acts as an endotoxin
role of lipopolysaccharide in gram-negative outer membrane
mycobacteria are considered gram-positive but have extra thick and complex ___
mycobacterial envelope
sterol-like molecules in cytoplasmic membranes of many bacteria
hopanoids
movement of water across a selectively permeable membrane
osmosis
-no net movement of water particles
-cell membrane is attached to cell wall
-solute concentration outside and inside the cell are equal
isotonic solution
