Week 2 Flashcards
Capsules
Structure- layer of polysaccharide or peptide that form hydrophillic gels around bacteria
Function- virulence, prevent dessication, preventing complement activation and phagocytic engulfment
Found in Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae
Causes meningitis and bacteremia in asplenic patients
Serotyping- K antigens
Flagella
Structure- long, helical filaments composed of flagellin attached to the basal body via a hook
Function- motility with basal body as the motor, movement is rotating; chemotaxis
Serotyping- H antigens
Recognized by host cellls through binding TLR-5
Pili (fimbrae)
Structure- long filamentous structures composed of pilin over bacterial surface
Function- mediating adherence, binds to specific receptors on host cell
Contributes to antigenic variation
Bacterial vs Eukaryotic ribosome
Bacteria- 70s composed of 50s and 30s
50s= 23s+5s RNA + 34 proteins
30s= 16s + 21 proteins
Eukaryotic- 80s composed of 60s and 40s
Bacterial replication and translation
Nucleoid DNA polymerase, oriC, DNA gyrase, binary fission, RNA polymerase, operon (1 promoter cluster of genes), polyribosomes
Spores
Formed by some gram-positive bacilli (Clostridium and Bacillus)
Develop within vegetative cells during adverse conditions; resistant to insult
Two types of metabolic process that bacteria utilize
Fermentation- organic compounds serve as electron don0r and acceptors, substrate level phosphorylation, inefficient, does not require oxygen, acid is by-product
Respiration- oxygen or nitrates are electron acceptors, electrons are transported across carriers, protonmotive force drives chemiosmosis ATP synthesis
Why need ATP: flagellar rotation, uptake of small molecules
Cytochrome C oxidase test to distinguish between Pseudomonas aeruginosa and Neisseria spp.
Transformation
Pieces of naked DNA released into the environment by lysed bacterial are taken up and incorporated into the chromosome of other bacterial cells
Natural vs artificial competency
Transduction
Bacteriophages act as vectors to introduce DNA from donor bacteria into recipient bacteria by infection
Generalized vs specialized
Conjugation
cell-to-cell contact between two cells leads to unidirectional transfer of genetic material from donor to recipient cell. Sex pilus is part of the conjugation machinery, sometimes F plasmid will integrate into host genome
Transposable Elements
Insertion sequences
Transposons
Plasmids
Non-conjugative vs Conjugative
Bacteriophage
Virulent phage- lytic infection
Temperate phage- lysogenic infection, virulence due to phage conversion
Integron
Genetic entities that capture exogenous gene cassettes and ensure their expression.
1) promoter 2) primary recombination site 3) gene encoding integrase
no intrinsic mobility
