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Immunoassays
Food Analysis Final Exam
What are three advantages of immunoassays? | Specific, sensitive, simple |
Name three applications of immunoassays. | Screening tests for pesticides, drug residues, foodborne pathogens, bacterial toxins, allergens, GMOS, etc. |
Define antigen. | Any molecule which induces the formation of antibodies and can bind antibodies. |
Define antibody. | Proteins produced by B cells in response to an antigen. |
Immunoglobulin is an example of an _____. | antibody |
Define Hapten. | Immunogen small molecules which must be linked to a carrier protein in order to induce antibodies - b/c molecules alone cannot induce antibodies. |
Define conjugate antigen. | A carrier protein-linked hapten molecule. |
___ antibody has the highest concentration in blood and is the most important class used in immunoassays. | IgG |
T or F: Binding strength between antibody and antigen is important for sensitivity of immunoassays. | True |
Define epitope. | The specific region of antigen in which the antibody is bound. |
Name the four interactions associated with antigen-antibody binding. | Ionic, hydrogen, hydrophobic, van der waals. |
What is the difference between polyclonal and monoclonal antibodies? | Polyclonal antibodies consist of many antibodies which can bind to many different epitopes on an antigen, whereas a monoclonal antibody can only bind one epitope. |
How is an antigen-antibody reaction measured? | Separate free antigen from bound antigen, and quantify bound antigen at low concentrations. |
Name the two most commonly used enzymes for immunoassays. | horseradish peroxidase, alkaline phosphatase |
Describe how ELISA works. | Enzymes link to a specific antigen or antibodies and absorb light, showing color when compound of interest is detected. |
Describe a non-competitive immunoassay. | The amount of antibody-antigen complex is measured by the amount of enzyme linked to antigen/antibodies. |
Describe a competitive immunoassay. | Involves a competition between the sample antigen and an added antigen binding to an antibody. |
The colored product intensity is directly related to amount of target molecule in _____ immunoassays. | non-competitive |
The colored product intensity is inversely realted to amount of target molecule in _____ immunoassays. | competitive |
What are two advantages to indirect ELISA over direct ELISA? | Increased sensitivity, differentiate antibody classes, use less immunoreagent. |
Sandwich ELISA is considered a _____ immunoassay. | non-comepetitve |
_____ ELISA can be used to detect large molecules such as proteins. | Sandwich |
_____ immunoassays can be used to detect both small and large molecules. | Competitive |
T or F: In a competitive immunoassay, the more absorbant means less antigen is present. | True |
What is the difference between bound hapten format and bound antibody format? | Enzyme linked antibody versus hapten binds the substrate respectively. |
What two techniques are combined in a Western blot? | SDS-PAGE, immunoassay |
What does a Western blot do? | Identifies target proteins and confirms their identity by molecular mass. |
Lateral flow strips are used to test for ____. | GMOs |