Eating habits - 4th set Flashcards
Glycocalyx sugar (poly)
is viscous, gelatinous material present on the external surface - composed mainly of polysaccharide. composition varies - synthesized inside cell and secreted outside onto cell surface
2 types of glycocalyx
Capsule: glycocalyx is well structured and firmly attached to cell wall
Slime layer : secreted portion is disorganized and loosely attached
capsule functions - passive defense
protection (anti-phagocytic) , slippery nature, protects from drying
I. Protection: due to it’s anti-phagocytic nature ( virulence factor)
A. protects pathogenic bacteria from host cell phagocytosis
2. slippery nature - makes it difficult to surround and engulf. bacteria gets inside cell, because of capsule, will remain in vesicle. fusion with lysosome is prevented. then bacteria replicate in phagocyte then out into cytoplasm.
3. protects cell from drying ; due to it’s functional capacity to bind and retain water molecules ( hydrophilic nature) prevents cell drying or desiccation
peptidoglycan (cell wall) (cheer stand)
large. tail, backbone and bridge. macromolecule and provides - rigidity and mechanical stability is due to highly cross linked structure
backbone (cleaners) (cell wall)
linear polymer of repeat disaccharide units - the units are made of alternating NAG and NAM linked by O - glycosidic linkage. Nag and nam modified glucose
molecule.
tail (snake) (cell wall)
tetrapeptide composed of alternating D and L amino acids because they are the isomers of the amino acids- attaches to NAM sugar via a complex linkage- minimizes tendency to form helices and provides an extended “rigid” - STABILIZES peptidoglycan structure peptide chain
bridge (chain) (cell wall) (2/3)
crosslink between parallel tetrapeptide side chains reinforces and confers 2 or 3 dimensional stability to the peptidoglycan structure. made of either short chain of amino acids or directly bonded to one another - links 3rd residue of one chain to the 4th residual amino acid of the adjacent tetrapeptide chain
incomplete phagocytosis
Incomplete phagocytosis is when the vesicle containing the engulfed bacteria fails / prevented from fusing with the lysosomes; lysosomal enzymes kills the engulfed cells
capsules do not..
transport - no role. everything freely permeates through capsule
prevnair 13
B cells activation by capsules chemical components. B cells are activated independent of T cells and are differentiated into antibody producing plasma cells as well as memory B cells Ab secreted by plasma cells protects against invading pathogens. Memory cells long half life; it’s differentiation into plasma cells BCR and cross linking by repetitive capsule components for B cell activation
B cells are part of adaptive immunity. B cells proliferation and differentiation following activation via BCR.
bacillus anthracis capsule not sugar but…
amino acid - polypeptides made of poly d. glutamic acid
staining of glycocalyx
staining and detection is by negative staining using acidic (anionic) dye
slime layer seen in..
bacteroids
capsule function
Protection: due to it’s anti-phagocytic nature ( virulence factor)
s. pyogenes (strep throat) - passive defense (serum)
has hyaluronic acid capsule, which impairs recognition by immune system, escapes detection by defense cells. it also has a slippery nature.
Streptococcus pneumoniae forms
capsulated form and non capsulated form
(capsulated is pathogenic, can escape and colonize) (non pathogenic - easily recognized and eliminated)
ex. of colonization
Streptococccus mutans and dental plaque scrape teeth to get rid of it.acids destroy tooth surface. it colonizes tooth surface, then produces acid from food particles. acid destroys tooth surface
capsule used to make vaccine
Vaccines : Brevnair -13 (capsule component from 13 different strains) vaccine against streptococcus pneumonia
13 different strains from pneumonia incorporated in vaccine.
activates b-cell receptors (BCRs). They bind to strep capsule. BCR and polysaccharid gets cross linked, then activation, proliferation, and differentiation
of B cell. then forms plasma cells, just differentiated B cells, the antibodies. B cells make antibodies, and they bind to bacteria, and prevent infection from initiating by bacterial cell. B cells are adaptive.
b cells made into memory..
cells, long half life. when infected again, memory cells will quickly differentiate to form plasma B cells (the antibodies).
cell wall below..
capsule
Cytoplasmic membrane =
Plasma membrane ≡ Inner membrane
External structures (membrane)
includes cell envelope and appendages
Internal structures (membrane)
are the accessory structures
appendages (membrane)
flagella, fimbriae, pili, endoflagella
accessory structures (membrane)
chromosome, plasmid, ribosomes, inclusions
inclusions (membrane)
volutin granules, polysaccharide granules, , β- Hydroxy butyric acid granules
gram - cell wall (where)
periplasm and periplasmic space. thin layered, suspended in the periplasmic space - stably anchored to outer membrane
Gram negative 2 pairs of rings
an outer and inner one (outer - cell wall. Inner - attached to cytoplasm - gram negative
active defense barrier
directs attack on host defense cells, like macrophages, T-helper cells, B cells. remain inside macrophages (riding in police car) and then multiply. ex. measles attacks B and T cells, can develop lethal pneumonia.
plasma membrane is…
is thin structure lies inside the cell wall, encloses cytoplasm- defines the external boundary of cell- plasma membrane components
dynamic role
plasma membrane - acts as selective barrier; monitors flow in both direction
• helps maintain constant, appropriate internal environment. ATP
plasma membrane structure
fluid mosaic - sea
plasma proteins
are in motion laterally: grouped into 2 classes, Integral proteins: permeases
Proteins: are in motion laterally: grouped into 2 classes,
Integral proteins: extend into or through the lipid bilayer - typically are trans membrane proteins.
peripheral - attach to inner and outer surface of membrane. functions as enzymes, scaffold, receptors etc
plasma membrane made of…
phospholipids, proteins, glycoproteins. no cholesterol - exception: Mycoplasma membrane
pbp
penicillin binding protein - facilitates bridge or crossbridge in gram positive and gram negative cells. pencillin causes osmotic lysis.
Protoplast
gram + cells stripped of its cell wall. osmotically fragile
Spheroplast
gram - cells partially stripped of its cell wall, can’t completely strip gram - cell wall - always some part still there
surgical would infection
s. aureus
spores have no
metabolism
the periplasmic space is between the
plasma membrane and the outer cell wall
bacillus anthracis germinates in
alveoli of lungs
cloistridium botulism germinates in
intestines
tail is always linked to
NAM - more functional groups to attach to
dextrorotary - D amino acid
less common
laveoratory - L amino acid
more common
alternating nag and nam prevent
helices from forming
lipotechoic acids (ft tech)
span the length and attach to plasma membrane lipids
wall techoic (bed wall)
embedded in peptidoglycan layer - cell wall
techoic acids hold..
everything together
gives negative charge to gram +
phosphate
lipoproteins in gram - (hip)
stably anchor peptidoglycan to outer membrane
teichoic acid provides..
antigenic specificity - we recognize it as foreign
pamps are on..
bacteria. it’s a barcode
techoic acids are found..
in our intestines, skin and oral cavity
tlr
is a prr on wbc. they recognize pamps - techoic acid. lipopolysaccharide, flagella, dna. cause inflammation.
pro-inflammatory cytokines - IL 1, 16 and 18
secreted from defense cells. promotes inflammation to eliminate pathogen
lipoproteins
anchor peptidoglycan in gram -
trans protein ex.
ex. cholera membrane trans protein acts as a biosensor.
pamps ex
capsule component such as poly D glutamic acid, D amino acids and teichoic acid
no transfer TRNA
in diaminopemlic acid, not a real amino acid
peptide bond allows for..
direct bridge in gram -
dedicated RNA in gram +
allows for links in bridge
outer membrane (lipopolysaccaride) is asymetrical bc..
2 leaflets
inner leaflet made of
phospholipids
outer leaflet made of
lipopolysaccharides (O and A)
porin proteins are
trans proteins and channel proteins
mac lysis is a ___response
innate
gram - in our body
e.coli and entobacterium
variable in gram -
sugar coating, not variable is the lipopolysaccharide.
- composition of polysaccharide varies amongst bacteria sps even in same species, polysac. different ex. E.Coli 0157:H7 (in cattle). E. Coli K12 -(human intestines). When 0157 gets inside humans from eating meat not cooked, it secretes toxin harmful to kidneys. Children cannot fight it. toxin and targets kidney cells in kids, blood vessels. most who died were kids or elderly.
syrum resistant strains
evolved to escape mac lysis - neissan gonorrhea
How bacterial membrane differs from eukaryotic membranes ?
Mycoplasma membrane unique feature
no cholesterol in
bacterial membrane, but it’s protected by rigid cell wall
has cholesterol
mycoplasma membrane, smallest living organism. no cell wall, so antibiotics don’t work on it.
not static
plasma membrane
disinfectants
lysol - it is phenol based organic solvent. always works on inanimate objects only. humans use antiseptic like alcohol. dissolves lipids, content leaks out, cell dies.
polymixin (neosporin)
binds to membrane phospholipids and disrupts membrane structure. alters permeability causing leakage, cell death. applied topically only.
endotoxin fever induction
bacteria recognized as non self, macrophage active, pick up bacteria,. oxygen will flush and bacteria will die and lipid A will be released. macrophage will be “activated” and it will secret interlukin 1 (which is pro-inflammatory) into bloodstream, travel to hypothalamus. activates an enzyme called cox enzyme, or cyclo oxygenic. will generate prostoglandins. it resets the switch for temperature regulation
lipopolysaccharide
It’s asymmetric lipid bilayer; made of, inner leaflet made of phospholipids. outer leaflet lipopolysaccride
anti-inflammatory drugs used when
TLRs are activated bc they cause inflammation
techoic acids inside us
intestines, skin, oral cavity, are called mamps
MAC is formed
typically on the surface of pathogen cell membranes as a result of the activation of the host’s complement system
the innate response is (storm)
complement protein, cytokine
pamps are just MLLTP
MLLTP
mycobacteria. lipopolysaccharide, lipoteichoic acids, peptidoglycan, lipoproteins. The body recognizes that pamps are invaders. used by innate immune.
advantages of fever
you take rest , and energy is used to fight bacteria. increased temperature may slow bacterial growth.
Increased temperature also enhances cellular reactions of the defense cells in eliminating pathogens (as we heat in chemistry to increase chemical reaction rates
1st line of defense (PCM)
physical barrier, chemical barrier, normal microflora
2nd line of defense
compliment proteins and MAC lysis, inflammation, phagocytosis
3rd line of defense
B and T cells (adaptive)
chemical barrier
ph of stomach lysosomes
