Characteristics Of Bacteria

Question 0

Characteristics of a Gram negative cell wall?

Answer 0

2 layers:

1) Inner peptidoglycan that is much thinner than Gram + cells
2) outer membrane is outside peptidoglycan layer and contains lipopolysaccharide
- acts as barrier to harmful substances
- acts as sieve; allows water soluble molecules to enter through protein lined pirons or channels
- provides attachment sites
- responsible for fever/shock in patients with Gram negative bacteremia

Question 1

Characteristics of a gram positive cell wall

Answer 1

1) Composed of thick protective peptidoglycan layer
- glycan (polysaccharide chains) of alternating N-acetyl-D-glucosamine (NAG) and N-acetyl-D-muramic acid (NAM)
- teichoic acid and lipoteichoic acid are unique to gram positive cell wall

Question 2

Characteristics of Bacteria?

Answer 2

Cell wall:

1) Gram +
2) Gram -
3) Acid fast cell wall
4) No cell wall

Question 3

Bacteriology Morphology?

Answer 3

Can vary in size 0.2-10 um; vary in shape

• cocci:
  a) diplococci
  b) streptococci
  c) staphylococci
• bacilli (rods)
  a) coccobacilli (short and plump)
  b) pleomorphic (variations in shapes)
  c) branching
  d) palisading (boxcars on a jackknifed train)

Question 4

Bacterial Shapes

Answer 4

3 general shapes dictated by the configuration of the cell wall

1) coccus
2) bacillus
3) coccobacillus
4) vibrio
5) spirillum
6) spirochete

Question 5

Bacterial arrangement

Answer 5

Style of grouping; influenced by pattern of division and how the cell remains attached afterward. Greatest variation in cocci
Cocci:
1) diplococci (pairs)
2) tetrads (groups of 4)
3) staphylococci/micrococci (irregular clusters)
4) streptococci (chains)
5) sarina (cubical packet)
Bacilli:
6) diplobacilli (pairs)
7) streptobacilli (chains)
8) palisades

Question 6

Additional bacterial components

Answer 6

1) Flagella
2) Pili or Fimbriae
3) Endospores
4) Capsules

Question 7

Factors affecting microbial growth

Answer 7

1) Temperature
2) Hydrogen ion concentration (how acidic)
3) Osmotic pressure of growth media
4) Chemical requirements (Carbon, water, N, S, P, trace elements)
5) Atmosphere (Oxygen, no oxygen, extra CO2)