Microbiology 3

Question 1

Describe the structure of fungi.

Answer 1

• Cellular structure more complex than bacteria
• Eukaryotic cell with a well-defined nucleus

Question 2

State the major sites of infection with fungal pathogens.

Answer 2

• Brain
• Mouth
• Lungs
• Vagina
• Circulation
• Skin

Question 3

What are some of the existing challenges with fungal pathogens?

Answer 3

• Early diagnosis
• limited anti fungal drugs
• Cytotoxicity of existing therapeutics
• Increasing anti fungal resistance
• Emerging pathogens

Question 4

State the traditional approaches to diagnose fungi.

Answer 4

• Direct microscopic examination of clinical samples
• Histopathology
• Culture
• Serology

Question 5

Why do techniques of culturing and observing fungi differ from methods used to study bacteria?

Answer 5

• Fungi grow at slow rates - requiring several days to weeks to form macroscopically visible colonies
• Molds produce spores on brightly coloured aerial hyphae

Question 6

How are fungi identified?

Answer 6

Based on visual characteristics such as colony morphology and colour

Question 7

Fungi are eucaryotes, what does this mean?

Answer 7

unaffected by those agents which selectively target uniquely procaryotic features such as peptidoglycans.

Question 8

State 6 features of viruses.

Answer 8

• they cannot be observed using a light microscope.
• they have no internal cellular structure.
• they contain either DNA or RNA, but not both.
• they are incapable of replication unless occupying an appropriate living host cell.
• they are incapable of metabolism.
• individuals show no increase in size.

Question 9

Describe the size of a virus.

Answer 9

They are much smaller than prokaryotic and eukaryotic cells; this is an adaptation
allowing viruses to infect these larger cells

Question 10

How can viruses be grown?

Answer 10

• in vivo (within a whole living organism, plant, or animal)
• in vitro (outside a living organism in cells in an artificial environment, such as a test tube, cell culture flask, or agar plate).

Question 11

Describe the viral life cycle.

Answer 11

1. Virus binds to host cell receptor
2. Virus penetrates and enters the cell by endocytosis
3. Virus uncoats and disassembles, introducing genetic material as RNA into the cell
4. A reverse transcriptase converts viral RNA into DNA
5. An integrase incorporates DNA into the cell’s chromosome
6. Cell produces new viral RNA which is the template for protein synthesis
7. A protease hydrolyses viral proteins into several small subunits
   8 and 9. New virus capsules are formed, bud off, and are extruded from the host cell by endocytosis, infecting new cells

Question 12

What are protozoans?

Answer 12

Eukaryotic and unicellular.
Do not have cell wall
Microscopic and able to
multiply in humans

Question 13

What are helmiths?

Answer 13

Large, multicellular organisms that are generally visible to the naked eye in their adult stages.
Like protozoa, helminths can
be either free-living or parasitic in nature. In their adult form, helminths cannot multiply in
humans.

Question 14

What are prions?

Answer 14

Type of protein that can cause disease in animals and humans by triggering normally healthy proteins in the brain to fold
abnormally.