Review Flashcards
(118 cards)
1
Q
What is different about prokaryotic flagella?
A
- No membrane coat
- Made out of flagellin
- No 9+2 arrangement. One tube
2
Q
Bacterial cell wall is made of:
A
NAG (N-aminoglycoside)
NAM (N-aminomuramic acid)
3
Q
Metachromatic cytoplasmic granules is indicative of:
A
Diptheria
4
Q
Why does E Coli have a weaker peptidoglycan layer?
A
Some of their side chains are NOT linked
5
Q
A gram negative stain indicates that the bacteria has how many layers?
A
3–outer membrane, PG layer, cytoplasmic membrane
6
Q
What is attached to the outer membrane of gram negative bacteria?
A
LPS and O specific side chains
7
Q
What is different about the outer layer of gram positives?
A
Thicker peptidoglycan layer interlaced with teichoic acid
8
Q
Which part of LPS is embedded in the cell membrane?
A
Lipid A
9
Q
Why is vancomycin ineffective against gram negative bacteria?
A
It is a large molecule that cannot get through the porins of the outer membrane to access the cell wall
10
Q
What type of bacteria is generally more resistant to detergents, bile salts, etc?
A
Gram negative
11
Q
Are porins selective?
A
Only selects by size
12
Q
What size molecules can pass through porins?
A
MW 600-700
13
Q
Why is the O-specific region important?
A
immunological specificity
14
Q
Name the steps involved in the gram staining procedure
A
- Crystal violet
- Iodine
- Decolorizer
- Red stain
15
Q
Why do only gram positive bacteria hold the violet dye?
A
- Thicker cell wall
2. Permeability difference in the two walls of the bacteria
16
Q
Capsules are non-essential for bacterial growth. Why are they significant?
A
- Resists phagocytosis
2. Can be antigenic
17
Q
What is the purpose of pili
A
Adherence to other cells/conjugation/twitch motility=pushing or pulling bacteria across a surface
18
Q
Which species of bacteria form spores?
A
Bacillus + Clostridia
19
Q
When rotation of flagella is counter clockwise, which direction does the bacterium travel?
A
Straight line forward
20
Q
When do bacteria secrete phospholipases?
A
When low levels of phosphorus or iron conditions occur
21
Q
How do bacteria extract host iron?
A
Using siderophores
22
Q
What temperature is needed to inhibit the growth of most bacteria?
A
4C or 40F
23
Q
Why is there a lag phase in bacterial growth?
A
Need time for the bacteria to synthesize necessary molecules for growth in the new medium
24
Q
What is the fermentation product of streptococcus pyogenes?
A
Lactic acid
25
What microbe produces butyric acid?
Clostridia. Also produces acetic acid and H2 in the process
26
Which microbes produce proprionic fermentation?
Propioni bacteriumand bifidobacterium
27
Which microbes use fixed acid fermentations?
enterobacteria
28
What does a mixed acid fermentation produce?
FOrmic acid, which can be broken down into CO2 and H2 by some organisms
29
How can you distinguish between shigella and salmonella?
Shigella=formic acid whilesalmonella=H2
30
How would you distinguish between non-fecal enteric bacteria vs fecal enterics?
Non-fecals form butanediol
| Fecal enterics form mixed acid fermentation to produce H2
31
Which bacteria produce ethanol?
Yeast and candida albicans (fungus)
32
What is the Strickland rxn?
Specialized fermentation that generates genergy by fermenting paris of amino acids. Done by clostridia
33
What necessary enzyme do obligate anaerobes lack, preventing them from living in aerobic environments?
Catalase, which decomposes H2O2
| Superoxide dismutase, which breaks down superoxide radicals
34
Examples of facultative anaerobes
E Coli and staphylococcus
35
Examples of aerotolerant anaerobes:
Lactobacillus and streptococcus
36
Examples of microaerophiles
Campylobacter Jejuni
37
Which bacteria can only grow in glucose not lactose?
Salmonella and shigella
38
Which bacteria can use neither glucose nor lactose?
pseudomonas
39
To use lactose, bacteria need what enzyme?
Galactosidase
40
Difference between a transition vs transversion mutation?
Transition=Changing from purine to purine
| Transversion=Changing from purine to pyrimidine
41
Difference between a true revertant vs supressor mutation?
Suppressors acquire a secondary mutation which restores the original phenotype. True revertants have a mutation that REVERTS the original mutation
42
Describe the point of the penicillin enrichment experiment
Identified auxotrophs. Auxotrophs will not grow in minimal media, and thus are protected form penicillin.
43
Complementation
This experiment determines which gene causes a particular observed phenotype. If two mutations complement each other to create a WT phenotype, you know that you have not identified the correct mutation
44
Why do bacteria need restriction enzymes?
To protect themselves from bacteriophages--will degrade their DNA
45
What are transposons?
Mobile genetic units that can insert themselves anywhere in the DNA through INSERTIION SEQUENCES. Results in illegittimate or nonhomologous recombination
46
What is bacterial competence?
Ability of a bacteria to be transformed
47
Explain mapping by generalized transduction
1. Grow a phage with WT host bacteria
2. Transfer those phages to mutant auxotrophic bacteria (AA1- AA2- AA3-)
3. Measure the % of colonies with two AA revertants
4. The higher percentage of colonies with 2 AA revertants indicates that those two genes are closer together
48
What is specialized transduction?
Phage DNA incorporates into the bacterial host chromosome at a specific place. In rare instances, the phage will take the same bacterial DNA with it. Will insert that host DNA into another bacteria
49
What is an Hfr strain?
A cell with an F+ plasmid integrated into the bacterial chromosome. Can transfer host DNA to bacteria
50
What are resistance transfer factors?
Conjugal plasmids carrying resistance genes
51
Which group of antibiotics alter membrane permeability?
Polymyxins and polyenes
52
Mechanism of action of penicillin?
Prevents cross linking of NAM and NAG. Growing cells will secrete bacterial autolytic enzymes, which lyse the cell.
53
Incompatibility groups
Plasmid grouping method--states plasmids are similar if they cannot coexist in the same bacteria--overlapping similarity prevents coexistence.
54
Penicillin G is effective against:
Gram positive cocci and SOME gram negative cocci
55
Which type of penicillin is sensitive to acid hydrolysis?
Penicillin G
56
What is the advantage of the aminopenicillins over Penicillin G/V?
Broader spectrum. Includes G- enteric bacilli
57
Which are the limited spectrum penicillins?
G and V
58
Which are the broader spectrum penicillins?
Ampicillin + Amoxicillin
59
Which are the extended spectrum penicillins? What additional protection do they provide?
Tricarcillin and piperacillin and PSEUDOMONAS
60
The penicillinase resistant penicillins are effective against what type of bacteria?
G+ bacteria
61
What type of bacteria can you use cephalosporins on?
G+ bacteria and SOME G- bacilli
62
What advantage do cephalosporins have over penicillins?
Acid stability and penicillinase resistance
63
Name 1st generation cephalosporin:
Cefazolin
64
Name 2nd generation cephalosporin
Cefuroxime
65
Name 3rd generation cephalosporin
Ceftriaxone and Ceftazidime
66
Give an example of a monobactam
Aztreonam
67
Give an example of a carbapenem
Imipenem
68
Aztreonam is effective against:
aerobic G- including pseudomonas
69
What is special about imipenem's spectrum?
Broadest antimicrobial spectrum
70
Name the beta lactamase inhibitors:
clavulonic acid and sulbactam
71
What is augmentin?
Combination therapy of amoxicillin + clavulonic acid
72
What is the mechanism of glycopeptides
Cell wall synthesis inhibitors
73
Name two glycopeptides
Vancomycin and teichoplanin
74
Cycloserine-Mechanism? Used to treat __-?
Inhibits cell wall synthesis. Tuberculosis
75
What is bacitracin's mechanism of action? What type of bacteria is it used to treat?
Interferes with murein synthesis. Gram + organisms. Topical use.
76
What is polymyxin effective on?
G- enteric rods and pseudomonas
77
How do polymyxins work?
Bind to LPS then causes membrane leakage.
78
How does daptomycin work?
Inserts into the cytoplasmic membrane of gram positive bacteria. Good for multiply drug resistant bugs
79
Name the aminoglycosides
Streptomycin, neomycin, gentamicin
80
Mechanism of action for aminoglycosides?
Inhibits initiation complex formation and misreading of proteins
81
What is special about tigecycline?
Prevents efflux pump from sending it out of the bacteria
82
Which drugs interfere with the 50S unit of protien synthesis?
clindamycin, chloramphenicol, erythromycin, azithromycin, sreptogramins
83
Are inhibitors of 50S bactericidal or static?
Static
84
Erythromycin's MOA
Prevents chain elongation
85
What is erythromycin effective against?
G+ bacteria, G= cocci, mycoplasma and chlamydia
86
Chloramphenicol's MOA
blocks chain elongation
87
Clindamycin MOA
Blocks peptidyl transfer. GOod for G+ and some anaerobes
88
Streptogamin MOA
Binds to 50S subunit. Good for MRSA, VREF
89
Synergin-what is it?
A combo sreptogamin. Dalfopristin and quinupristin
90
How do oxazolidinones work?
Interferes with protein synthesis through tRNA translocation
91
Name a drug in the oxazolidinone group
linezolid
92
Mupirocin mechanism of action
Binds to tRNA synthetase
93
Is mupirocin bacteriostatic or bacteriocidal?
Bacteriostatic, but can become bacteriocidal at high concentrations
94
What is mupirocin useful against?
MRSA
95
Name the quinolones
Ciprofoxacin and moxifloxacin
96
Side effect of quinolones
Adverse effect on growing bone--contraindicated in children and pregnant women
97
Nitroimidazole mechanism of action
Fragments DNA
98
Name a drug in the nitroimidazole class
metronidazole
99
Metronidazole can be used for
anaerobic bacteria and protozoa
100
Which classes of antibiotics interfere with DNA replication?
Quinolones
| Nitroimidazole
101
Which class of antibiotics inhibit RNA synthesis?
Rifampin
102
What is ethambutol used for?
Anti-TB bacteriostatic
103
What is pyrazinamide used for?
Anti-TB
104
What is Rifampin used for?
Meningitis
105
What is needed to activate nitroimidazoles?
ferredoxin
106
What does it mean to sanitize?
Lower the bacterial content
107
Cationic detergents do not work against:
Pseudomonas or TB
108
Which antifungal drugs alter membrane permeability?
Polyene compounds
109
Which anti-fungal drugs bind to sterols in the membrane?
amphotericin and Nystatin
110
Which anti-fungal drugs affect cell membrane synthesis?
Azoles (fluconazole and ketoconazole)
111
What is a fungal antimetabolite? Is it bacteriocidal or static?
Flucytosine. 5-fluorouracil replaces uracil. Inhibits DNA synthesis. Can be bacteriostatic or bacteriocidal
112
Mechanism of action of caspofungin? Is it bacteriostatic or bacteriocidal?
Caspofungin inhibits glucan synthesis. It is a fungicidal
113
H2O2 can be used to kill
anaerobes
114
Silver nitrate
inactivates bacterial enzymes
115
Resistance to aminoglycosides is due to
phosphorylating enzymes
116
Resistance to sulfonamides is due to:
alteration in dihydropterase synthase, preventing drug from binding to it
117
Resistance to tetracycline stems from
Tetracycline efflux pumps
118
UV light kills bacteria because it is:
mutagenic. Changes DNA.
