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Disease & Defense - Unit 2 > Introduction to Bacteria > Flashcards

Introduction to Bacteria Flashcards

1
Q

Major structural features of bacteria (general)

A
  1. cell wall 2. characteristic shape 3. characteristic cell surface structures 4. 70S Ribosome 5. Nucleoid
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2
Q

Functions of external cell wall

A
  1. resisting osmotic lysis 2. maintaing cell shape
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3
Q

General structure of peptidoglycan layer

A

polymer w/repeating units of hexose sugars (GlcNAc & MurNAc) linked to tetrapeptide chains w/bacteria-specific amin acids (meso-DAP, D-glutamic acid, & D-alanine); peptidoglycan chains cross-link

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4
Q

Gram-negative vs. Gram-positive peptidoglycan layer

A

1.Gram-negative=thin, sparsely cross-linked 2. Gram-positive=thick, cross-linked++, w/teichoic acids

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5
Q

Composition of OM of gram-negative bacteria

A

lipid bilayer=lipopolysaccharide (LPS) + lipoproteins (covalent link to peptidoglycan) + porins + phospholipids

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6
Q

Function of OM of gram-negative bacteria

A
  1. barrier to entry of some anitbiotics 2. protects against detergents/toxins
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7
Q

LPS of gram-negative bacteria structure

A

LPS=Lipid A (endotoxin component) + core poly sacc + oligosaccarachide (O antigen)

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8
Q

Teichoic acid structure

A

TA=repeating polyglycerol-P or polyribitol-P backbone w/some substitutes covalently linked to peptidoglycan

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9
Q

Capsule structure and fxn

A
  1. outer surface layer of complex polysaccharides 2. enhance virulence by resisting phagocytosis
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10
Q

Flagella structure and fxn

A
  1. appendages originating in cytoplasmic membrane, composed of cytoskeleton elements. 2. molitily/chemotaxis
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11
Q

Pili structure and fxn

A
  1. protein, hair-like structure on surface 2. adherence to surfaces and tissues 3. sex pili–>bacterial conjugation
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12
Q

Cytoplasmic membrane structure and fxn

A
  1. lipid bilayer=phospholipids+proteins 2. physiological barrier btwn inside and outside of cell 3. selective permeability 4. electron transport system 5. transport metabolites 6. biosynthesis 7. DNA replication 8. flagellar rotation
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13
Q

Nucleoid structure

A
  1. distinct region of cytoplasm=location of tightly coild DNA; no nuclear membrane
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14
Q

Types of DNA present in bacteria

A
  1. Chromosome=double-stranded, circular DNA 2. Plasmid=extra-chromosomal, self-replicationg DNA, often encode virulence factors
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15
Q

Bacteriophage definition

A

viruses that infect bacteria; genomes may incorporate into bacterial chromosome; change in phenotype=”phage conversion”

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16
Q

Phases of bacterial growth (4)

A
  1. lag phase 2. exponential phase 3. stationary phase 4. death phase
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17
Q

Characteristics of lag phase

A

incolum=period of physiologic adjustment; establish enzymes/intracell enviro for growth on new medium

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18
Q

Characteristics of exponential phase

A

growth rate proportional to cell number/mass; generation time=doubling time (time required to double cell number/mass)

19
Q

Characteristics of stationary phase

A

essential nutrients consumed and toxic metabolites acumulate; cell growth slows or stops; most bacteria in nature

20
Q

Characteristics of death phase

A

number of viable bacteria decrease over time; autolysis occures

21
Q

Minimal requirements for bacterial growth

A
  1. certain inorganic ions 2. carbon source 3. energy source
22
Q

heterotrophic bacteria definition

A

bacteria that require organic carbon source (most bacterial pathogens)

23
Q

autotrophic bacteria definition

A

bacteria that obtain carbon exclusively from CO2

24
Q

fastidious bacteria definition

A

lacking in one+ biosynthetic pathways; require growth factors

25
Q

Strict Aerobic bacteria (1. Aerobic growth? 2. Anerobic growth? 3. Example)

A
        • (Requires O2; cannot ferment) 3. mycobacterim tuberculosis
26
Q

Strict Anaerobic bacteria (1. Aerobic growth?2. Anerobic growth? 3. Example)

A
        • (Killed by O2; ferments) 3. Clostrium or Bacteroides sp
27
Q

Aeritolerant anaerobic bacteria (1. Aerobic growth? 2. Anerobic growth? 3. Example)

A
        • (Ferments w/ or w/out O2 present) 3. Streptococcus pyogenes
28
Q

Facultative Anaerobic bacteria (1. Aerobic growth?2. Anerobic growth? 3. Example)

A
        • (Respires w/O2, Ferments w/out) 3. E. Coli or Staphylococcus aureus
29
Q

Microaerophilic bacteria (1. Aerobic growth?2. Anerobic growth? 3. Example)

A
      1. ++ (Grows best at low O2, can grow some w/ or w/out O2) 3. Campylobacter jejuni
30
Q

2 types of “energy currency” in cells

A
  1. ATP 2. electrochemical gradients/proton motive force
31
Q

Fermentation definition

A

organic compounds=electron donors and acceptors; no net oxidation of substrates

32
Q

Respiration definition

A

generation of ATP through electron transport w/O2 as final electron acceptor

33
Q

Selective toxicity definition

A

selective inhibiton of microbial growth at drug concentrations tolerated by the host; principle on which antimicrobials work

34
Q

Major categories of antimicrobial targets (5)

A
  1. Cell wall-active antimicrobials 2. Outer/cytoplasmic membrane-active antimicrobials 3. Inhibition of protein synthesis 4. Inhibition of nucleic acid synthesis 5. Metabolic inhibitory antimicrobials
35
Q

Antibiotics w/cell wall target

A
  1. B-lactams (penicillins, cepalosporins) 2. Vancomycin 3. Cycloserine
36
Q

Antibiotics w/cytoplasmic membrane target

A

Polymyxins

37
Q

Antibiotics w/protein synthesis target

A
  1. Aminoglycosidase (streptomycin, kanamycin, etc.) 2. Tetracyclines 3. Chloramphenicol 4. Macrolides & Lincomycins
38
Q

Antibiotics w/DNA synthesis target

A
  1. Quinolones 2. Rifampicin
39
Q

Antibiotics w/metabolic target

A
  1. Sulfonamides 2. Trimethoprim 3. Isoniazid 4. Metronidazole
40
Q

Sulfonamide target/action

A

strucutral analog of p-aminobenzoic acid –> inhibits folic acid synthesis –> inhibits nucleic acid synthesis

41
Q

Trimethoprim target/action

A

inhibits dihydrofolate reductase –> inhibits folic acid synthesis –> inhibits nucleic acid synthesis

42
Q

Isoniazid target/action

A

inhibits lipid synthesis in mycobacteria

43
Q

Metronidazole target/action

A

interferes w/anaerobic metabolism

44
Q

anaerobic respiration definition

A

ATP generation via electron transport w/inorganic substrates as terminal electron acceptors

Disease & Defense - Unit 2 (10 decks)

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