Term
| What is the purpose of a cell wall? |
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Definition
| protects organism against osmotic pressure and gives cell shape; often contains teichoic acid |
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Term
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Definition
| during extreme conditions to ensure survival; germination = vegetative structure during normal cellular processes |
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Term
| What type of microscope can magnify an organism 1000-2000x, but does not have good resolution? |
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Definition
| light microscope - can use UV or infrared |
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Term
What type of microscope can magnify an organism 100,000x's, has to be fixed, and has better resolution?
What are the 2 types? |
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Definition
electron microscope
SEM: scans surface of cell
TEM: transmission; cross-section of cell |
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Term
| What is darkfield microscopic examination? |
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Definition
| dye binds to background of slide, not the organism; it is a negative stain |
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Term
| What type of direct assay measures quantitatively as well as qualitatively? |
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Definition
Immunological - ELISA (direct detects Ag and indirect detects Ab) and Radioimmune assays (RIA)
**These tests can detect 10^3-10^4 particles, are fairly simple, quick (1-4 hours), and can detect infectious as well as non-infectious particles |
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Term
| Nucleic acid probes, a type of direct assay, labels (RNA or DNA segments) with a radioactive or chemical marker? |
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Definition
BOTH - homologous sequences of viral (or bacterial) genomes react with the probe
**Detects 1-1000 particles; may detect infectious and non-infectious particles |
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Term
| Which type of direct assay amplifies specific segments of DNA or RNA, is rapid, sensitive, and specificity can be varied? |
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Definition
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Term
| T/F: In an infectious assay, whole animals or cell cultures can be used |
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Definition
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Term
| What are the 4 types of biochemical tests used to detect the presence of organisms in a cell culture? |
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Definition
1. Fermentation of sugars
2. Utilization of carbon sources (citrate)
3. Deamination of AA's
4. Hydrolysis of proteins, DNA, lipid |
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Term
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Definition
| An immunological test: Ag and Ab are placed on opposite sides of a plate and separated - diffusion leads to a precipitate at optimal Ag-Ab concentration |
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Term
| If an antibody binds to an enzyme and inhibits it's activity, what type of antibody is it? |
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Definition
Anti-enzyme antibody - neutralizes
(example: Streptolysin O antibody prevents lysis of RBC's) |
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Term
| T/F: Monoclonal Ab's involve different classes (IgG, IgA, IgM, etc.) that can react with different sites on the microorganism |
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Definition
False - involves on type of antibody with one specific site
**Polyclonal Ab's occur when animals are immunized with whole microorganism of fractions (multiple epitopes) |
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Term
What does a HAT selection media consist of?
When is this used? |
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Definition
H - Hypoxanthine (precursor of adenylate)
A - Antifolate (blocks synthesis of adenylate and thymidylate)
T - Thymidine (precursor of thymidylate)
Spleen/Myeloma hybrid cells: Spleen cells are HGPRT+ and utilize hypoxanthine, but don't grow in vitro; Myeloma cells can replicate in cell culture media, but are inhibited by antifolate and are HGPRT -. Together, the cells can grow in vitro and in animals. |
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Term
| T/F: DNA probe (homologous DNA) + isolated DNA from pathogen = positive identification |
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Definition
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Term
| T/F: PCR is rapid, sensitive, specific, and can detect virulence/toxin genes within a bacteria |
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Definition
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