Week 1- Flashcards
Describe Bacteria
- Prokaryotes (no nucleus)
- Unicellular microorganism
- Rigid complex cell wall
- Reproduce by binary fission
- Majority grow aerobic, anaerobic or microaerophilic conditions and some require cells to grow
- Variable staining properties
True/ False Bacteria has a complex cell wall with a unique component called peptidoglycan
True
What is a unique cell wall component of bacteria?
peptidoglycan
What is a unique cell wall component of gram positive bacteria?
Lipoteichoic acid (for antigenicity)
What is a unique cell wall component of gram negative bacteria?
Outer membrane containing Lipopolysaccharide (LPS) (virulence factor)
What is a unique cell wall component of mycobacteria?
mycolic acid (virulence factor)
What is acid fast staining due to
due to presence of mycolic acid
What bacterial structure contributes to antigenicity?
Pili/Fimbriae
Which bacterial species has a non-polysaccharide capsule
anthrax
How can bacterial growth be measured?
Colony counting, turbidimetry, flow cytometry
Define/describe exotoxins
exotoxins are proteins produced by bacteria and released to outside- they exert action of specific target cells. (neurotoxins, leukotoxins, enterotoxins) Majority are heat labile
Characteristics of endotoxin
Heat stable, cell wall component of bacteria, released when bacteria are dead or killed, can induce inflammation by stimulating the immune system
Describe superantigens
- Produced by pathogenic microbes (including viruses, mycoplasma, and bacteria)
- Indiscriminate binding to MHC class II molecule on the APCs and T Helper cell receptor
- Results in polyclonal T cell activation and massive cytokine release
Two examples of superantigens
Staphylococcus, streptococcus enterotoxins.
What is biofilm? Give example
Microbes come together in masses cling to surfaces, produce extracellular substances and take in nutrients and forms a biofilm. Ex. dental plaque (pseudomonas aeruginosa biofilms
Describe the transfer of virulence factors between bacteria
Virulence factors are transferred between bacteria through processes such a conjugation, transformation and transduction
What are plasmids and bacteriophages
Plasmids are smaller circular DNA present in bacteria.
Bacteriophages are virus particles which attack bacteria
-Plasmids and bacteriophages may carry genes for antibiotic resistance, toxins, capsules and fimbriae and can mediate transfer.
How does bacteria or fungus cause disease?
- Depleting the host’s nutrients by using them
- Direct damage to the host cell (toxins)
- As a result of immune response to the microbe or a combo of all these
Cell wall component unique to Gram negative bacT
LPS
Gram positive staining in some bacteria is due to the presence of
a thick peptidoglycan layer
