Flashcards in Bacteriology Deck (20)
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1
Sterols are found in the cell membranes of eukaryotes or prokaryotes?
Eukaryotes
2
What is the difference between brightfield and darkfield microscopy?
1. In darkfield, a special condenser is used to prevent transmitted light from directly illuminating the specimen (only scattered light reaches the specimen, causing it to become bright against a dark background)2. Improved resolution in darkfield for visualization of thin bacteria
3
What type of microscopy allows visualization of internal details?
Phase contrast
4
What are characteristics of gram positive bacteria?
1. Thicker peptidoglycan layer2. Teichoic acid often present3. Sporulation in some strains4. Capsule sometimes present5. Sensitive to lysozyme6. More sensitive to penicillin7. Exotoxin production in some strains
5
What are characteristics of gram negative bacteria?
1. Outer membrane2. Thinner peptidoglycan layer3. LPS present4. Capsule sometimes present5. Resistant to lysozyme6. More resistant to penicillin7. Exotoxin production in some strains
6
What are characteristics of acid fast bacteria?
Peptidoglycan layer intertwined with covalently attached arabinogalactan polymer and surrounded by a waxlike lipid coat of mycolic acid
7
What forms the rigid structure of the cell wall?
Peptidoglycan
8
What are the steps of gram staining?
1. Crystal violet2. Crystal violet precipitated with iodine3. Decolorizer / wash4. Red safranin counter stain
9
Where does stain get trapped in gram positive bacteria?
Peptidoglycan layer
10
Where is LPS found?
Outer leaflet of gram negative outer membrane
11
What are the three components of LPS?
1. Lipid A2. Core polysaccharide3. O antigen
12
What is essential for LPS's bacterial viability?
Lipid A
13
What is essential for LPS's endotoxin activity?
Lipid A
14
What feature of LPS distinguishes serotypes of bacterial species?
O antigen
15
What does LPS bind to?
CD14 and TLR4 on phagocytes and APCs
16
What are pili?
1. Tube like structure made of proteins 2. Hollow core 3. On surface of gram negative and gram positive
17
What test is used to identify bacterial capsules?
Quellung
18
Do gram negative bacteria form endospores?
No
19
Do gram positive bacteria form endospores?
Some can
20
