Microbe-host

Question 1

Symbiosis

Answer 1

Living together

Question 2

Mutualistic

Answer 2

Both partners benefit

Question 3

Parasitic

Answer 3

one partner takes nutrients/resources from the
other

Question 4

Commensal

Answer 4

one partner benefits, the other is unaffected

Question 5

Endosymbiosis

Answer 5

a symbiosis in which the bacterial symbiont
lives inside the host’s cells

Question 6

Examples of endosymbioses:

Answer 6

1. the origin of eukaryotic cells
2. Buchnera and insects (aphids)
3. bacteria and tube worms
4. nitrogen-fixing bacteria and legumes

Question 7

The Endosymbiotic Theory:

Answer 7

about 1 billion years ago, an endosymbiosis led to the development of eukaryotic cells
•mitochondria evolved from rickettsiae, a group of bacteria that are obligate intracellular parasites, even now
•chloroplasts evolved from cyanobacteria, a group of photosynthetic bacteria
•genomes of mitochondria (37 genes) and chloroplasts (128 genes) are very much reduced in size compared to the genomes of modern-day
rickettsiae or cyanobacteria
•many genes were transferred to the nuclear genome or lost, as the endosymbiont came to rely on its host

Question 8

Virulence factors of E.coli that allows to adhere and colonize on the surface of the intestinal epithelium

Answer 8

-type 3 secretion and intimin

Question 9

Virulence factors of tetanus

Answer 9

-exotoxin

Question 10

Virulence factor of anthrax

Answer 10

-antiphagocytic capsule and anthrax toxin

Question 11

Example of a virulence factor for evading host defenses

Answer 11

-Hyaluronidase: an enzyme produced by streptococci that digests hyaluronic acid, a glue like substance that helps hold the cells of certain tissues together

Question 12

Virulence factors

Answer 12

structures or proteins produced by pathogens that help them to cause disease

Question 13

Examples of virulence factors

Answer 13

structures for adhesion—> adhesions, capsules, pili

-enzymes or structures that help in evading host defenses—> hyaluronidase, antiphagocytic capsules

-toxins that can cause disease directly–> exotoxins and endotoxins

-secretion systems for delivery of toxins–> type III or type IV

Question 14

opportunists

Answer 14

Organisms that take advantage of particular opportunities to cause disease

Question 15

Microbial antagonism

Answer 15

-normal microbiota ordinarily competes with pathogens for nutrients

Question 16

under what conditions would an opportunist pathogen be able to cause disease?

Answer 16

-failure of the hosts normal defenses
(when the host is immunocompromised)
-introduction of the organism into unusual body sites
(e.coli in surgical wounds)
-disturbance in the normal microbiota
(microbial antagonism)

Question 17

Pathogenicity

Answer 17

the capacity to produce disease

Question 18

Pathogen

Answer 18

an organism that causes disease

Question 19

Virulence

Answer 19

refers to the intensity of the disease produced by pathogens

Question 20

How did the Wallace et al. seek to alleviate side effects of the colon cancer drug CPT-11?

Answer 20

-used inhibitors
-inhibitor 1 of beta glucuronidases prevent the conversion of SN-38G to SN-38 and diminish CPT-11 gut toxicity