This antibody is linked to an enzyme, and, in the final step, a substance containing the enzyme's substrate is added. The subsequent reaction produces a detectable signal, most commonly a color change in the substrate. Performing an ELISA involves at least one antibody with specificity for a particular antigen. substrate for the enzyme is applied, and catalysis by the enzyme leads to a change in color or fluorescence. ELISA results are reported as a number; the most controversial aspect of this test is determining the cut-off point between a positive and a negative result.
The University operates a two semester academic year with each semester running for approximately 13 teaching weeks followed by 2 weeks of examination. Semester I usually starts during the last week in August and ends late December. Semester II starts about late January and ends around mid May.
Summer classes can be between 3 and 11 weeks, depending on the colleg â¦ e and the subject. Semesters are about 4 months in duration. The fall semester is from late August or early September to December; the spring semester is usually from January to late April or early May.