Studying for Micro Exam 13

TRUE or FALSE: With an A-B toxin, the A domain affects the host cell and the B domain is used to bind to the host.

True

What type of microorganisms are mycorrhizae?

a) viruses

b) fungi

c) bacteria

d) plants

b) fungi

What are the 5 steps to an infection? Provide a few words (no more than one sentence) about why each of these steps is important.

1. Entry: this is how the pathogen gets into the host

2. Adherence and colonization: allows pathogens to bind to receptor cells which allows an infection to occur

3. Multiply and evade host defenses: allows pathogens to survive by evading host defenses and allows for pathogen to multiply in host

4. Damage host tissue: allows pathogens to harm host tissue, exotoxins, and endotoxins for example

5. Exit: allows pathogen to leave the host

Which bacterial genus is a symbiotic nitrogen-fixing bacteria?

a) Beijerinckia

b) Clostridium

c) Rhizobium

d) Azotobacter

c) Rhizobium

We discussed numerous mechanisms of immune evasion. Choose your favorite and explain how it works in no more than 3 sentences.

Invasins are surface proteins that rearrange the actin filaments on the host’s cytoskeleton.

This allows germs to enter the cell.

Invasins push the actin around so the germ can slip inside the cell.

In the video we watched on Tuesday, what type of symbiotic relationship was demonstrated? What effect does this have on each of the partners in the relationship?

It demonstrated parasitism.

One benefits and the other is harmed.

Which of the following is an example of a process made possible via symbiosis?

a) The presence of bacteria in the rumens of cattle aid in digesting cellulose

b) Thermus aquaticus functions at temperatures as high as 95 C

c) The archaeal microbe Picrophilus torridus grows at pH at 0.06

d) The bacterium Salinibacter ruber grows at a salinity ranging from 20-30%

a) The presence of bacteria in the rumens of cattle aid in digesting cellulose

Of what values are siderophores?

a) They help prevent phagocytosis by host immune cells.

b) They promote adhesion to host cells

c) They help bacteria obtain iron from human cells

d) They induce membrane ruffling of human cells

c) They help bacteria obtain iron from human cells

TRUE or FALSE: Endotoxins are proteins produced mainly by Gram-positive bacteria and are secreted by the cell to affect the host.

False

____ immunity prevents microbes from entering the human and ____ immunity has a memory component.

Innate immunity prevents microbes from entering the human and adaptive immunity has a memory component.

Please provide 2 physical factors of the first line of defense and give an approximately 1 sentence explanation for each describing how they act as a defense against infection.

• Ciliary escalator – Tiny hairs sweep germs up and out of the lungs.

  • Epidermis of skin – Dry and always shedding, so germs can’t stick or grow

What relationship do Toll-like receptors have to pathogen-associated molecular patterns?

Toll-like receptors on human cells bind pathogen-associated molecular patterns on bacterial cells inducing the release of cytokines.