Intro to Micro

Question 1

What is the bacterial cell wall material?

Answer 1

Peptidoglycan

Question 2

What is the source and effect of cholera toxin?

Answer 2

Cholera toxin disrupts chloride channels such that chloride rushes out of the cell, followed by Na+ and water, which causes severe diarrhea

Question 3

What is the organization of the Baltimore classification scheme (and the no. of classes)?

Answer 3

7 types: DNA vs RNA and structure (cylindrical, icosahedral, or complex; size, and envelope)

Question 4

Define immune escape.

Answer 4

Antigenic variation, or mutation of the antigens that would allow the immune system to recognize the virus, allows the virus to escape detection

Question 5

Where does VZV hide from the immune system?

Answer 5

In the dorsal root ganglion, before traveling down the sensory nerves to the skin to cause a rash, known as shingles

Question 6

Define virulence.

Answer 6

Virulence is the relative capacity to cause damage to the host

Question 7

What factor of the virus does attenuation decrease?

Answer 7

Virulence

Question 8

Why can most fungi not cause disease in humans?

Answer 8

Their optimal growth temperature is much lower than 37°C

Question 9

Name three components of the fungal cell wall (innermost to outermost).

Answer 9

Chitin, β-glucans, galactomannans

Question 10

What is the major fungal membrane molecule that differentiates fungi from animals?

Answer 10

Ergosterol

Question 11

What are the three main types of pathogenic fungi?

Answer 11

Yeasts, molds, and thermally dimorphic fungi

Question 12

What is the difference between environmental and colonizing fungi?

Answer 12

Their “natural” habitat outside of humans; Coccidioides is a soil fungus and Candida is a mucosal colonizer

Question 13

What are the two main categories of parasites?

Answer 13

(1) Protozoa, eukaryotic, single-celled organisms and (2) multicellular eukaryotes such as helminths and ectoparasites

Question 14

Name two groups disproportionately affected by parasitic infections

Answer 14

Agriculture workers, women during pregnancy, children, and poor people living in wealthy countries

Question 15

What are three different kinds of hosts in a parasitic life cycle?

Answer 15

Definitive host: hosts the parasite during reproduction stage; intermediate host: hosts the parasite during larval development; dead-end host: parasite enters the wrong host and dies

Question 16

What are two bactericidal compounds secreted by epithelial cells?

Answer 16

Acid in stomach, bile detergents in intestine (microbes could change LPS to withstand detergents), antimicrobial peptides and enzymes (microbes could change the cell wall to resist lysozymes), IgA (microbes could produce IgA proteases)

Question 17

What is the biggest clinical concern about bacterial biofilms?

Answer 17

Biofilms can act as a barriers, allowing bacteria to avoid the immune system! Catheter-related bloodstream infections often require removal of the device

Question 18

What are the four common mechanisms of antibiotic resistance?

Answer 18

(1) Decrease entry by mutating the porin proteins in the cell membrane (gram-negative bacteria specifically), (2) degrade the antibiotic by producing B-lactamases, (3) remove the antibiotic by producing efflux pumps, (4) alter the target by mutating the ribosome