1 Which bacterial cellular component can elicit a potent host response even afte
ID: 150880 • Letter: 1
Question
1 Which bacterial cellular component can elicit a potent host response even
after the bacteria is lysed
A. Lipopolysaccharide
B. Plasmid
C. Fimbriae
D. Porins
E. Type 6 Secretion System effectors
2 You are studying the effects of an uncharacterized emerging pathogen in the
lab by infecting cultured mammalian cells with your new bacteria. You observe a
change in morphology and cellular function of the cultured cells a day after infection.
Further analysis finds that a small segment of bacterial DNA has been moved into
the chromosome of the cultured cells. What is the most likely mechanism?
A. A bacteriophage from the bacteria has infected the mammalian cells
B. Your cultured cells were contaminated with something other than the bacteria
under study
C. The mammalian cells acquired naked DNA from the environment
D. The bacteria has a type 4 secretion system
E. You didn’t really have a good understanding of the cultured cells used in the study
3 Which organism would be least susceptible to decontamination by hand
washing?
A. Influenza A, an enveloped RNA virus
B. Acinetobacter baumannii, a Gram negative opportunistic pathogen
C. Naegleria fowleri, the brain-eating amoeba
D. Parvovirus, a naked DNA virus that causes Fifths disease
E. Mycoplasma pneumoniae, a peptidoglycan deficient bacteria that causes walking
pneumonia
4 What is one difference between Type 3 and Type 4 secretion systems?
A. Only Type 4 can translocate DNA or proteins
B. Type 3 is a molecular syringe while Type 4 is a “bolt gun”
C. Type 3 uses ATP to translocate effectors, while Type 4 used NADH
D. Type 3 is anchored in the cell membrane, while Type 4 is anchored in the PG
E. Type 3 is derived form a flagella while Type 4 is derived from a bacteriophage
5 Which killed or inactivated organism would give the most robust immune
response if introduced into a person’s blood stream?
A. Enveloped virus
B. Naked virus
C. Gram positive bacteria
D. Gram negative bacteria
E. Prion
6 Which of the following is likely not a pathogenicity determinant used by
gastrointestinal pathogens to cause disease in a eukaryotic host?
A. Enterotoxin
B. Flagella
C. Type 3 Secretion System
D. Endospore
E. Mycolic acids
Explanation / Answer
1. A. Lipopolisaccharides.
Bacterial lipopolisaccharides can elicit potent host immune response even after the lysis of the bacterial pathogen. This property is exploted in preparation of vaccines to combat many bacterial pathogens.
2. A. A bacteriophage from bacteria may have infected the mammalian cells.
Recent research have shown that bacteriophages can infect higher organisms and can integrate DNA but can not multiply in those cells.
3. Acinatobacter baumannii, a Gram negative opportunistic pathogen.
It is least likely to be susceptible to decontamination by hand washing.
4. A. Only type 4 secretion system can translocate DNA or proteins (the property lacking in type 3 secretion system).
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