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TT DD ex 3 and BL ex 2 > 1 DD Bacterial Structure, Function and Growth > Flashcards

1 DD Bacterial Structure, Function and Growth Flashcards

1
Q

List structural features of bacteria

A
  1. Capsules
    1. Pili aka Fimbriae
    2. Rigid external cell wall
      • Peptidoglycans
    3. Cytoskeletal elements
    4. Cytoplasmic membrane
    5. Flagella
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2
Q

Capsule:

  • describe
  • purpose
  • Why do we even care?(How do we take advantage of it?)
A

a. Outer complex polysaccharide layer→ Gelatinous and loose as a goose
b. Purpose: protects against phagocytosis → “enhance virulence”
c. Most capsular polysaccharides are antigenic →used as components of vaccines to prevent bacterial infections

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3
Q

Pili “fimbriae”

  • describe
  • purpose
  • Why do we even care?(How do we take advantage of it?)
A

a. Long, slender, antigenic hair-like glycoproteins on surface

b. Function: bacterial adherence
i. Some (few) bacteria: sex pili → bacterial conjugation

c. Can make antibodies against pili → block bacterial adherence → resist bacterial infection

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4
Q

Peptidoglycans

  • describe
  • purpose
  • Why do we even care?(How do we take advantage of it?)
A

a. Rigid polymer of repeating NAM and NAG. Makes up external cell wall

b. Purpose:
i. Structure and strength for cell wall (not shape)

c. Peptidoglycans are unique to bacteria- → great target for antibiotics.

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5
Q

Rigid external cell wall

  • describe
  • purpose
A

a. Made of peptidoglycan in Gram (+)
Made of peptidoglycan and outer membrane in Gram (-)

b. Purpose: Cell shape + resisting osmotic lysis

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6
Q

Describe differences in Peptidoglycan content in gram (+) vs gram (-) bacteria

A

Gram (+) bacteria: greater extent of peptidoglycan cross-linking
**Gram Positive: think P for Puffier Peptidoglycan

Gram (-) bacteria: lesser extent of peptidoglycan cross-linking
** Gram Negative: think N for Not as much peptidoglycan

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7
Q

What is another name for the two hexose, NAG and NAM?

A

N-acetylglucosamine (GlcNAc or NAG)

N-acetylmuramic acid (MurNAc aka NAM)

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8
Q

Intracellular cytoskeletal elements

  • purpose
  • describe its components
A

a. Purpose: Determines cell shape

b. Bacteria tubulin: FtsZ
c. Bacteria actin: MreB and ParM
d. Bacteria Intermediate filament protein: CreS (crescentin)

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9
Q

Cytoplasmic membrane

- describe

A

Lipid bilayer of phospholipids and lots of proteins (60-70%)

  • Anatomical physiological barrier between inside and outside of cell
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10
Q

List different functions of cytoplasmic membrane (6)

A

i. Selective permeability
ii. Electron transport
Iii. Transport of metabolites
iv. Biosynthesis of lipids and cell envelope components
v. DNA replication
vi. Flagellar rotation

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11
Q

Flagella

  • purpose
  • types of movement
A

Function: motility → used to move bacteria during chemotaxis

i. Counter-clockwise: swimming (unidirectional)
ii. Clockwise: tumbling  (ie clumsily changing direction)
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12
Q

Types of Flagella

A

i. Polar: 1 or several flagella at 1 end

ii. Peritrichous: flagella distributed over surface

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13
Q

Whats another name for cytoplasmic membrane? In which Gram type of bacteria would you use this name?

A

Inner membrane in Gram (-) bacteria

  • note: gram (-) bacteria also have an outer membrane
  • gram + bac have no outer membrane - only 1 general plasma membrane
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14
Q

Whats another name for Pili?

A

Fimbriae

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15
Q

Why do we care about flagella?

example

A

Most are antigenic → can be used for classification

1) Ie: H antigens of enteric bacteria

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16
Q

List bacterial structures that are antigenic

A

capsules
pili
Flagella

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17
Q

Nucleoid

A

aka nuclear body - where DNA is located in bacteria

18
Q

Whats the difference between bacteria chromosome and plasmid?
- give an example of a plasmid

A

i. Chromosome: a single, double-stranded, circular DNA molecule

ii. Plasmid: smaller, extra-chromosomal, self replicating DNA molecules → code for virulence factors
1) Ie: R factors: plasmids that carry genes that determine resistance to antibiotics

19
Q

Describe layers of Gram (+) bacteria

A

2 layers total:
- 1 layer of cell wall:
□ Thick, extensively linked peptidoglycan layer containing teichoic acids
- 1 plasma membrane layer

Lipotechoic acid underneath cytoplasmic membrane

20
Q

Lipoteichoic acid:

A

found attached to underlying cytoplasmic membrane of gram + bacteria → anchor cell wall (peptidoglycan) to membrane

  • only found in gram +
21
Q

Teichoic acid

A

Repeating bacterial polysaccharides (polyglycerol-P aka Polyribitol-P backbone) → extends peptidoglycan surface

-only found in gram +

22
Q

Describe layers of Gram (-) bacteria

A 
3 layers total:
	 2 layers of cell wall:
		□ Outer membrane
		□ Thin, sparsely linked peptidoglycan layer
	 1Plasma membrane
23
Q

Function of outer membrane of Gram (-) bacteria

A

□ Barrier against antibiotic entry

□ Protection against detergents and toxic compounds

24
Q

Components of outer membrane of Gram (-) bacteria

A

lipopolysaccharide (LPS), lipoproteins, and porins

25
Q

lipopolysaccharide (LPS)

A

polysaccharide containing

  1. Lipid A
  2. Core polysaccaride
  3. O side chain oligosaccharides
26
Q

Lipid A and O side chain oligosaccharides

-Where are they found and What are they:

A

Found in LPS of outer membrane of Gram - bacteria

Lipid A - the toxic component of endotoxin

O side chain oligosaccharides - function as somatic antigens aka O antigen

27
Q

Phases of bacterial growth curve

A
  1. lag phase
  2. exponential(logarithmic) phase
  3. Stationary phase
  4. Death phase
28
Q

Based on classifications of energy sources, the majority of bacteria are?

A

Heterotrophic - requires organic carbon

29
Q

autotrophic organisms

A

obtain carbon exclusively from CO2

30
Q

Fastidious organisms

A

requires carbon and essential growth factors (aa, vitamins, purines, pyrimidines, inorganic ions)

-Deficient in 1/more biosynthetic pathways → requires rich growth media

31
Q

Facultative anaerobe

A

respires w/ low O2

ferments in absence of O2

32
Q

What type of bacteria grows best at low O2 [ ], AND

can grow without O2?

A

microaerophilic

33
Q

Which energy currency is used for flagellar rotation?

A

Proton motive force (PMF)

34
Q

Fermentation

A

catabolic process in which organic compounds serve as both e- donor and acceptor

35
Q

Do heterotrophic bacteria use fermentation or respiration to generate energy and reducing power?

A

Both

36
Q

List antimicrobial agent targets

A
  1. Cell wall
    2. Outer and cytoplasmic membrane
    3. Protein synthesis at ribosome levels
    4. Nucleic acid synthesis.
    5. Metabolism
37
Q

What bacterial structures are unique to gram + bacteria?

A

lipoteichoic acid

38
Q

What bacterial structures are unique to gram - bacteria?

A 
porins
LPS endotoxin
periplasmic space (beta lactamase location)
39
Q

Name for Bacteria tubulin

A

FtsZ

40
Q

Name for Bacteria actin

A

MreB and ParM

41
Q

Name for Bacteria Intermediate filament protein

A

CreS (crescentin)

TT DD ex 3 and BL ex 2 (21 decks)

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