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Flashcards in Introduction to Bacteria Deck (44):
1

Major structural features of bacteria (general)

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

2

Functions of external cell wall

1. resisting osmotic lysis 2. maintaing cell shape

3

General structure of peptidoglycan layer

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

4

Gram-negative vs. Gram-positive peptidoglycan layer

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

5

Composition of OM of gram-negative bacteria

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

6

Function of OM of gram-negative bacteria

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

7

LPS of gram-negative bacteria structure

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

8

Teichoic acid structure

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

9

Capsule structure and fxn

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

10

Flagella structure and fxn

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

11

Pili structure and fxn

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

12

Cytoplasmic membrane structure and fxn

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

13

Nucleoid structure

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

14

Types of DNA present in bacteria

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

15

Bacteriophage definition

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

16

Phases of bacterial growth (4)

1. lag phase 2. exponential phase 3. stationary phase 4. death phase

17

Characteristics of lag phase

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

18

Characteristics of exponential phase

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

19

Characteristics of stationary phase

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

20

Characteristics of death phase

number of viable bacteria decrease over time; autolysis occures

21

Minimal requirements for bacterial growth

1. certain inorganic ions 2. carbon source 3. energy source

22

heterotrophic bacteria definition

bacteria that require organic carbon source (most bacterial pathogens)

23

autotrophic bacteria definition

bacteria that obtain carbon exclusively from CO2

24

fastidious bacteria definition

lacking in one+ biosynthetic pathways; require growth factors

25

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

1. + 2. - (Requires O2; cannot ferment) 3. mycobacterim tuberculosis

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

1. - 2. + (Killed by O2; ferments) 3. Clostrium or Bacteroides sp

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

1. + 2. + (Ferments w/ or w/out O2 present) 3. Streptococcus pyogenes

28

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

1. + 2. + (Respires w/O2, Ferments w/out) 3. E. Coli or Staphylococcus aureus

29

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

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

30

2 types of "energy currency" in cells

1. ATP 2. electrochemical gradients/proton motive force

31

Fermentation definition

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

32

Respiration definition

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

33

Selective toxicity definition

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

34

Major categories of antimicrobial targets (5)

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

Antibiotics w/cell wall target

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

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Antibiotics w/cytoplasmic membrane target

Polymyxins

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Antibiotics w/protein synthesis target

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

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Antibiotics w/DNA synthesis target

1. Quinolones 2. Rifampicin

39

Antibiotics w/metabolic target

1. Sulfonamides 2. Trimethoprim 3. Isoniazid 4. Metronidazole

40

Sulfonamide target/action

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

41

Trimethoprim target/action

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

42

Isoniazid target/action

inhibits lipid synthesis in mycobacteria

43

Metronidazole target/action

interferes w/anaerobic metabolism

44

anaerobic respiration definition

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