9 Intro to microbiology

Question 1

What percentage of cells in the body are of human origin?

Answer 1

10%

Question 2

What are Koch’s postulates?

Answer 2

Organism must be isolated from every individual with the disease and artificially cultivated.
When inoculated from the culture, typical symptoms must result.
Organism must be recoverable from individuals who are experimentally infected.

Question 3

What are Koch’s postulates for genes? (5)

Answer 3

Gene should be active in virulent strain and silent in non-pathogenic strain.
Disruption should stop pathogenicity.
Introduction should transform.
Must be expressed in infection.
Antibodies should protect against disease.

Question 4

What are the four problems with Koch’s postulates?

Answer 4

Difficulty in isolating causative agent.
Impossible to grow some organisms artificially.
Ethical objections.
Animal models are insufficient.

Question 5

What is the structure of viruses?

Answer 5

Nucleic acid core (DNA/RNA). with protein coat (made of capsomeres). +/- an envelope.

Question 6

What is the accepted theory regarding causation of spongiform encephalopathies?

Answer 6

Prions.

Question 7

What are fungi cell walls made from?

What is the structure of moulds?

Answer 7

Chitin.

Hyphae form mycelia which may be subdivided by septa.

Question 8

What are protista?

What are the four classes of protista?

Answer 8

Unicellular eukaryotes.
Apicomplexa (sporozoa).
Flagellate protista.
Ciliate protista.
Amoebae.

Question 9

What is special about pneumocystis jiroveci?

Answer 9

A fungus that responds to anti-protist medication.

Question 10

What is the difference between the envelopes of g-ve and g+ve bacteria?

Answer 10

G+ve: 40 layers of peptidoglycan.

G-ve, less peptidoglycan, with an extra membrane of polysaccharides and lipid A.

Question 11

What is the difference between flagella, pili and fimbriae?

Answer 11

Flagellae: movement.
Pili: join cells during conjugation (exchange genetic material).
Fimbriae: aid adhesion.

Question 12

How does streptococcus mutans stick to the surface of teeth?
What does it cause there?

Answer 12

Slime. (Produced by other bacteria too).

Forms plaques -> dental caries.

Question 13

Which type of bacteria sticks to plastics using slime?

Answer 13

Coagulase negative staphylococci.

Question 14

What is the advantage of producing endospores to bacteria?

Answer 14

Highly resistant structure conferring heat, radiation and desiccation resistance.

Question 15

What is the term for bacteria with animal reservoirs?

Answer 15

Zoonoses.

Question 16

Which infections are commonly transmitted via drinking water contaminated with faeces?

Answer 16

Typhoid
Cholera
Dysentry
Hepatitis A
Poliomyelitis.

Question 17

What are fomites?

Answer 17

Inanimate objects that act as vectors of infection.

Question 18

What are intoxication illnesses?

Three examples.

Answer 18

Diseases that don’t require the victim to encounter the live microorganism.
Tetanus, botulism, ergotism.

Question 19

What are aggressins?

example?

Answer 19

Soluble antigens with combine with antibodies to produce circulating immune complexes. Become trapped in blood vessels.
Glomerulonephritis from Streptococcus pyogenes.