A11 IND

Question 1

Describe the four categories of bacteria?

Answer 1

Cat1: Gram NEG with cell walls
Cat2: Gram POS with cell walls
Cat3: Eubcateria with no cell walls
Cat4: Archeobacteria

Question 2

Explain serotyping and phage typing.

Answer 2

Serotyping is the use of specific antibodies and agglutination, used on GRAM NEGATIVES.
Phage typing utilises macrophages for GRAM POSITIVES.

Question 3

What are the typical sizes of prokaryotes and eukaryotes?

Answer 3

Pro = 0.2-2.0 um
Euk = 10-100 um

Question 4

Explain the structure of a Gram+ cell.

Answer 4

Gram + have a cell membrane and a large peptidoglycan cell wall with teichoic acids that are extrinsic and lipoteichoic acids that are intrinsic, and with mycolic acids it makes them difficult to stain. Acid fast stains are used instead.

Question 5

Explain the structure of a Gram- cell.

Answer 5

Outer membrane layer with porins, lack the lipoteichoic acids.

Question 6

What bonding occurs in cell walls and what strengths to they provide?

Answer 6

Glycosidic bonds that provide lateral strength.

Peptide bonds that give vertical strength.

Question 7

How are endospores produced?

Answer 7

The DNA is replicated and the cytoplasmic membrane invaginates to create a cell membrane - The “forespore” is engulfed and the original DNA is disintegrated. The endospore develops an outer spore coat and infects.

Question 8

What is the function of india ink?

Answer 8

Used to distinguish between capsules and slime layers.

Question 9

State some growth factors of bacteria.

Answer 9

AAs, cholestrol, heme, NADH + vitamins.

Question 10

What are the three thermocategories of bacteria?

Answer 10

Psychrophiles 45, Mesophiles 20-40.

Question 11

Explain the steps of bacterial reproduction.

Answer 11

Binary fission - Replication of genetic material, cell elongation, formation of new cell membrane and wall, then separation.

Question 12

Define fermentation, oxic, and anoxic fermentation.

Answer 12

Fermentation is the catabolism of organic compounds to yield free energy.
Oxic: Yeast respiration with no fermentation products.
Anoxic: NADH recyling, pyruvate to ethanol or lactic acid.

Question 13

Explain defined, complex, selective, differential, and transport media.

Answer 13

Defined: all essential nutrients, exact composition and quantities known.
Complex: Broad range of nutrients, unknown exact composition.
Differential: Visible changes in media.
Selective: Contains factors that promote the growth of one and inhibits the growth of another. (Eg High Na, Low pH.)
Transport: Supports clinical samples during transport.

Question 14

What are endogenous and exogenous sources of infection?

Answer 14

Endo: GI, genital tract and skin (INSIDE)
Exo: Direct, airborne, food, drink. (OUT)

Question 15

Explain Kochs Postulates.

Answer 15

An organism found in all cases of disease but not in healthy animals is a disease.
Pathogens cannot be isolated on artificial media, may require human host.

Question 16

What are the main aims of virulence factors?

Answer 16

Colonisation, Immunosuppression, Obtaining nutrition.

Question 17

Explain the relevance of iron in terms of pathogenicity.

Answer 17

Pathogens thrive on iron, so excess iron can increase susceptibility to infection. Pathogens can cut out the requirement for iron!

Question 18

Explain the three main exotoxins.

Answer 18

Cytolytic: Degrade erythrocytic membranes.
AB: inhibits proteinsynthesis.
Superantigen: Destroy everything.

Question 19

Give an example of an endotoxin, name a source.

Answer 19

Lipopolysaccharides, lead to toxic shock.

Produced by Gram+

Question 20

Describe 5 METHODS of antimicrobial control.

Answer 20

Aseptic - Assurance that area is clear from infection.
Sanitization - Meeting public health standards.
Sterilisation - Destruction of microbes from an object.
Degerming - Removing microbes by mechanical means eg alcohol, swabbing.
Disinfecting - Removing microbes of non-living tissue.

Question 21

Describe 5 EXAMPLES of physical antimicrobial control.

Answer 21

Autoclaving (pressure cooking)
Pasteurisation (heat)
Incineration (burning)
Desiccation (removing water)
Radiation (UV)

Question 22

Describe the model of immune responses, innate vs adaptive.

Answer 22

Innate has a high initial response then a minimal response from then on.
Adaptive has a steady increase, then decrease, then minimal.

Question 23

Distinguish between primary and secondary lymph tissue.

Answer 23

Primary: Bone marrow + thymus, generate and mature B/T lymphocytes.
Secondary: All other tissue that deal with stimulation, proliferation.