Bacterial Pathogenesis

Question 1

Which type of horizontal gene transfer involves the bacterial taking up environmental DNA?

Answer 1

Bacterial transformation

*Shown by Griffiths experiment with mice and s. pneumoniae

Question 2

Cells that are able to take up DNA are said to be?

Answer 2

Competent

*most frequently take up DNA from same genus

Question 3

Which horizontal gene transfer type is phage mediated?

Answer 3

Bacterial transduction

Question 4

Which horizontal gene transfer type involves pili to transfer genetic information?

Answer 4

Conjugation (bacterial sex)

Question 5

What are the 4 plasmid types?

Answer 5

1-Fertility plasmid (contains tra gene to express pili)
2-Col plasmid (code for bacteriocins that can kill other bacteria)
3-Virulence plasmid (codes for virulence factors)
4-Resistance plasmid (codes for resistance against poisons or antibiotics)

Question 6

DNA elements that move from one place to another and can disrupt genes or carry virulence/antiobiotic genes are called what?

Answer 6

Transposons (Jumping genes)

Question 7

Differing in G/C content, what virulence genes come in a distinct compact region?

Answer 7

Pathogenicity Islands

Question 8

The mechanism used by some bacteria to inject toxins and other proteins into cells through molecular syringes are called what?

Answer 8

Type III secretion Systems (T3SS)

Question 9

What are the two types of bacterial adherence mechanisms?

Answer 9

1-Pili-dependent adhesion

2-Pili-independent adhesion (surface structure interacts with host receptor)

Question 10

Bacteria residing in extracellular space posses what to survive?

Answer 10

Factors that allow them to prevent uptake and destruction by phagocytes. Varying antigenic surface and secretions that modify host

Question 11

What are some ways bacteria have adapted to survive inside the host cell?

Answer 11

• Resist Reactive oxygen species and NO

- Neutralize/prevent phagolysosome

Question 12

Listeria monocytogenes (G+) uses what cell structure to move around?

Answer 12

Actin tail forms to move it around and spread cell to cell

Question 13

What are 3 ways that bacteria have evaded amino acid starvation?

Answer 13

1-Transform to dormant state (C. Trachomatis(G-))
2-Make their own AA (M. Tuberculosis(AFB))
3-Degrade proteins and transport free AA in (L. Pneumophila(G-))

Question 14

What are the 3 types of virulence factors?

Answer 14

• Type 1: Bind and act at host cell surface (Super antigens)
• Type 2: Act on host cell membrane (Pore forming toxins)
• Type 3: A-B type toxins, include single chain (DT) and multisubunit toxins (cholera/anthrax)

Question 15

LPS (Toll-like mechanism) and Trachial cytotoxin (TCT) (Arrests ciliary movement) are both examples of what?

Answer 15

Non-protein endotoxins

Question 16

Encoded on a large plasmid, what toxin causes apoptosis/necrosis resulting in Buruli ulcers?

Answer 16

Mycobacterium ulcerans polyketide-derived mycolactone

Question 17

What class of toxin binds class II MHC to TCR and exhausts the T cell eventually killing it?

Answer 17

Superantigens

Question 18

Which bacteria is commonly found in the nasal cavity, causes food poisoning, toxic shock, and abscesses?

Answer 18

Staphylococcus Aureus (G+)

Question 19

How are many of the virulence factors encoded by S. Aureus regulated?

Answer 19

Quorum sensing (Auto inducers produced by the bacteria help them know how many more of themselves are near by)

Question 20

What are two membrane-disrupting toxins?

Answer 20

Phospholipases and Pore-forming toxins

Question 21

In A/B toxins the A subunit is responsible for ________ and the B subunit mediates _________ to a receptor and transferring the A subunit across the membrane

Answer 21

Enzymatic activity, Binding

Question 22

What toxin causes mucosal cells to pump large amounts of Cl- out resulting in diarrhea, loss of electrolytes and dehydration?

Answer 22

Cholera toxin

Question 23

A formation of a pseudomembrane in the throat and lungs is caused by what?

Answer 23

Diptheria Toxin

*enters via Heparin binding epidermal growth factor like receptor

Question 24

A non-toxic version of a toxin used as a vaccine is called what?

Answer 24

Toxoid