structure Flashcards
types of glycans making up cell wall and how they form it together with peptides
N-acetylglucosamine and N-acetylmuramic acid form sugar backbone and ensyme transpeptidase links backbones together.
Peptide chain that cross links glycan backbone
things found in the cytoplasm
Ribosomes, plasmis, genetic material, enzymes, ions, and granules
types of granules in cytoplasm
- made of polysaccharides, lipids, polyphosphates
gram positive bacteria have high glycogen stores - metachromatic/volutin granules made up of polyphosphates, RNA and proteins used as a source of P for the cell
species that metachromatic granules
Corynebacterium species, Yersinia pestis, Mycobacterium species
mention an inhibtor of cell wall synthesis
Beta Lactam antibiotics
types of thecoic acids
-ribitol thecoic acids 5 carbon and associated with the cell wall
-glycerol thecoic acids 3 carbon associated with tthe inner aspect of the cell membrane
what are Thecoic acids
-TA are water soluble anionic polymers of polyol phosphates covalently linked to peptidoglycan
function of thecoic acids
-stabilize the cell wall
- distinguish bacterial serotypes
- maintain association between cell wall and membrane
- adherance to surfaces; other bacteria or receptors
- stimulate WBC and macrophages to release cytokines ( initiates innate responses similar to endotoxin) VIRULENCE
what is present in gram positive cell walls apart from TA?
Antigens; polysaccharide (lancefield) or protein (griffith)
gram negative outer membrane functions
- protects peptidoglycan from affects of lysozyme and ingress of antibiotics- has beta lactamase enzyme to render antibiotics ineffective
- many LPS
structure of LPS and their uses if any
Lipid A- immunogenic component, essential for bacterial viability, activates b cells, and induces macrophages, dendtriic celss etc… induces fever and shock
Core polysaccharide
Surface exposed carbohydrate O antigen- antibody attachment site, distinguishes serotypes
explain acid fast bacterial cell wall structure
- modification of gram positive cell wall.
- peptidoglycan layer attached to arabinogalactan, attached to mycolic acid
bacterial cells with acid fast cell wall and type of mycolic acid they have
Corynebacterium species- 30 carbon
Nocardia species- 50 carbon
Mycobacteria- 90 carbon
function of mycolic acid in mycobacteria
Virulence, cell membrane cytotoxicity, inhibition of polymorphonuclear cell migration
what are plasmids
smaller circular extrachromosomal DNA
not essential for survival but confer resistance to 1 or more antibiotics
stain used to show the presence of metachromatic granules
albert’s stain
capsule: how can it be seen and what is it made up of
via light microscope
organized polysaccharide network in most but found as a polypeptide in Bacillus species
function of capsule
important for survival within host
MAJOR VIRULENCE FACTOR :
-antiphagocytic
- resistance to bactericidal action of complement and serum antibodies
- adherance to bacterial cells and mucosal surfaces
- protects cell from dessication and toxic materials
examples of encapsulated bacteria
Streptococcus pneumoniae
Haemophilus influenzae
Neisseria menengitidis
Neisseria gonorrhoeae
Streptococcus pyogenes
slime layer structure and function
loose polysaccharides
allow adherane to cell surface na dforeign materials
mention 4 type sof complement pathways
Classic, alternative Lectin to form the Common pathway
Explain classic pathway
initiated by immune complexes that activating C1q
antibody binds to antigen on pathogen and changes shape to expose its complement binding sites. Complement C1 binds and sets off reaction cascade which is an amplifying process
Explain the Lectin pathway
Mannose binding lectin (plasma protein) binds to mannose resideus on microbial cells and sets off reaction cascade leading to C3b production
Explain Alternative pathway
initiated by binding of spontaneously generated C3b proteins to target cells. Triggers reaction cascade with autocatalytic effect (more breakdonw of C3 proteins)
about complement proteins
grou p of 30 or more globulins that contribute to innate and adaptive immunity. synthesized by the liver and circulate in the blood in inactive form.
what are the 4 end results of the complement system
- Inflammation
- Chemotaxis or Immune Clearance
- Opsonization or Phagocytosis
- Cytolysis or destruction of membranes
what takes place once common pathway is achieved
Membrane attack complex is formed —> damage of cell membrane and lysis of target cell
function of flagella
-cellular motility- escape from defense mechanisms
-flagellar antigens (H) are used in identification
-
structure of flagellum
Basal body, Hook and filament
helically coiled protein subunits driven by ATP
difference between flagella of gram + and -
+ has 2 rings in basal body and - has 4 rings in basal body
types of flagella (5 types) and meaning
Monotrichous- single at 1 pole
Lophotrichous- 2 or more at one pole
Peritrichous- all over
Amphitrichous- 1 at each pole
Amphilophotrichous- tuft of flagella at each pole
example of monotrichous bacteria
Vibrio metchnikovii
example of lophotrichous bacteria
Spirillum serpens
example of peritrichous bacteria
Proteus vulgaris
about fimbrae (6)
- found in both gram + and -
- non flagellar hairline appendages
- short and thin
- found in large numbers
- formed from bacterial chromosome
-adhesion of bacterial cell to cell an mucous membrane
about pili (5)
- only in gram negative
- transfer of DNA/nuclear material in conjugation
- long and thick
- small numbers
- made from plasmid
bacteria that can from endospores
Aerobic endospore forming gram positive rods- Bacillus species
anaerobic endospore forming gram positive rods- Clostridium species
what is an endospore and why does it form
spherical or oval dormant structure
forms in response to nutritional deprivation
allows for resistance against harsh environments
Explain the sporulation process
1.replication of genetic material in mother cell
2. septum forms between copies
3. forespore is engulfed by the membrane of the mother cell.
4. Calcium rushes into endospore componenets and all water is expelled.
5. Coat and Cortex synthesis
6. Spore maturation and mother cell lysis
what is the core of an endospore made of
copy of DNA and cytoplasmic contents, surrounded by 2 membranes and peptidoglycan.. Made of calicum ionstightly cross linking the peptidoglycan layer
what is the cortex of the endospore
thin inner layer of tightly cross linked peptidoglycan. surrounded by keratin protein coat.
layers of en endospore
core, inner membrane, spore wall/ germ cell wall, cortex, outer membrane, protein coat and exosporium
