Week 1-

Question 1

Describe Bacteria

Answer 1

• Prokaryotes (no nucleus)
• Unicellular microorganism
• Rigid complex cell wall
• Reproduce by binary fission
• Majority grow aerobic, anaerobic or microaerophilic conditions and some require cells to grow
• Variable staining properties

Question 2

True/ False Bacteria has a complex cell wall with a unique component called peptidoglycan

Answer 2

True

Question 3

What is a unique cell wall component of bacteria?

Answer 3

peptidoglycan

Question 4

What is a unique cell wall component of gram positive bacteria?

Answer 4

Lipoteichoic acid (for antigenicity)

Question 5

What is a unique cell wall component of gram negative bacteria?

Answer 5

Outer membrane containing Lipopolysaccharide (LPS) (virulence factor)

Question 6

What is a unique cell wall component of mycobacteria?

Answer 6

mycolic acid (virulence factor)

Question 7

What is acid fast staining due to

Answer 7

due to presence of mycolic acid

Question 8

What bacterial structure contributes to antigenicity?

Answer 8

Pili/Fimbriae

Question 9

Which bacterial species has a non-polysaccharide capsule

Answer 9

anthrax

Question 10

How can bacterial growth be measured?

Answer 10

Colony counting, turbidimetry, flow cytometry

Question 11

Define/describe exotoxins

Answer 11

exotoxins are proteins produced by bacteria and released to outside- they exert action of specific target cells. (neurotoxins, leukotoxins, enterotoxins) Majority are heat labile

Question 12

Characteristics of endotoxin

Answer 12

Heat stable, cell wall component of bacteria, released when bacteria are dead or killed, can induce inflammation by stimulating the immune system

Question 13

Describe superantigens

Answer 13

• Produced by pathogenic microbes (including viruses, mycoplasma, and bacteria)
• Indiscriminate binding to MHC class II molecule on the APCs and T Helper cell receptor
• Results in polyclonal T cell activation and massive cytokine release

Question 14

Two examples of superantigens

Answer 14

Staphylococcus, streptococcus enterotoxins.

Question 15

What is biofilm? Give example

Answer 15

Microbes come together in masses cling to surfaces, produce extracellular substances and take in nutrients and forms a biofilm. Ex. dental plaque (pseudomonas aeruginosa biofilms

Question 16

Describe the transfer of virulence factors between bacteria

Answer 16

Virulence factors are transferred between bacteria through processes such a conjugation, transformation and transduction

Question 17

What are plasmids and bacteriophages

Answer 17

Plasmids are smaller circular DNA present in bacteria.
Bacteriophages are virus particles which attack bacteria
-Plasmids and bacteriophages may carry genes for antibiotic resistance, toxins, capsules and fimbriae and can mediate transfer.

Question 18

How does bacteria or fungus cause disease?

Answer 18

• Depleting the host’s nutrients by using them
• Direct damage to the host cell (toxins)
• As a result of immune response to the microbe or a combo of all these

Question 19

Cell wall component unique to Gram negative bacT

Answer 19

LPS

Question 20

Gram positive staining in some bacteria is due to the presence of

Answer 20

a thick peptidoglycan layer