Lecture 12: Bacterial Exotoxins Flashcards
True or False: Exotoxins are nucleic acids
False - proteins
True or False: Exotoxins are found in gram negative and positive bacteria and can be detected at human/animal/insect cells
True
True or False: Exotoxins can be made into effective vaccines and treat conditions like CP
True
True or False: Exotoxin is important for survival and propagation of bacterium that produce them
True
Where are the toxin genes commonly carried on?
1.
2.
1) Plasmids and 2) Lysogenic bacteriophages - e.g Diptheria
True or False: Some exotoxins are not excreted. Rather, they accumulate inside cell and are released by cell lysis.
True
____: a specific term that denotes exotoxins released by bacteria in intestines, which can cause diarrhea or vomiting
Enterotoxin
___ is embedded in bacterial surface and released when bacteria lysis
LPS (endotoxin)
What are the three types of toxins?
- Type 1 (Superantigen toxins/surface acting)
- Type II (Membrane-Disrupting Toxins)
- Type III Toxins (A-B Toxins)
Type ___ Toxins bind to host cell surface but is not translocated into host cell. Further, it allows for binding to MHC Class II and receptor on T cells that interact with MHC.
Type I
Many ___ cells can be stimulated by bridging action of superantigens
A. B cells
B. T cells
C. Macrophages
B. T cells
What symptoms arise as a result of Type I toxins?
Nausea, vomit, malaise, fever (toxic shock syndrome)
Three examples of type 1 toxins?
- TSST (S. aureus)
- Streptococcal
- Enterotoxin (E. coli)
Which toxin lysis the host cell by disrupting integrity of their cytoplasmic membranes?
A. Type 1
B. Type 2
C. Type 3
B. Type 2
What are the two different types of Type 2 (Membrane Disrupting) Toxins?
- Pore forming cytotoxins
- Enzyme cytotoxins
The primary role of Type II toxins is to kill host cells, particularly ____
phagocytes
S. aureus alpha-hemolysin is an example of which bacterial exotoxin?
A. Type 1
B. Type 2
C. Type 3
B. Type 2 - pore
Invasive bacteria use Type __ exotoxins to escape from phagosome and enter host cell cytoplasm
A. Type 1
B. Type 2
C. Type 3
B. Type 2
_____ cytotoxins insert into host cell membrane and make open channel (pore), which triggers a sudden inrush of water. This causes cell to swell and rupture.
A. Enzyme cytotoxin
B. Pore-forming cytotoxin
B. Pore-forming cytotoxin
Which Type II toxin destabilizes host cell membranes by either 1) removing charged head group of lipid portion or 2) cleave at other sites on the phospholipid
A. Enzyme cytotoxin
B. Pore-forming cytotoxin
A. Enzyme cytotoxin
Phospholipase, hemolysin, and cytotoxin are examples of which type of Type II toxin?
A. Pore-forming exotoxin
B. Enzyme cytotoxins
B. Enzyme cytotoxins
True or False: Type III (A-B Toxins) Toxins are extracellular acting
False - intracellular
In Type III Exotoxins, the A subunit is the active, ___ light chain while the B subunit is the heavy chain and is responsible for __
enzymatic; binding
True or False: In both simple and complex Type III Exotoxins, the B portion binds to a specific host cell receptor, then translocation regions moves A portion into host cell cytoplasm (either via : endocytosis or directly)
True
The compound AB toxin has a B portion made up of __ subunits and __ A subunit
A. one; multiple
B. multiple; one
B. multiple; one