IMMUNOLOGY VIRTUAL LAB WORKSHEET Go to http://www.hhmi.org/biointeractive/immunology-virtual-lab. Start the Virtual Lab. Answer the following questions in the spaces provided. 1. What is the principle of the ELISA based on? 2. Is the ELISA you performed a Direct ELISA or Sandwich ELISA? Explain your answer 3. What are five variables that could affect your result? 4. ELISA's are quantitative in nature. Why are serial dilutions performed in this assay? What would happen if the sample is not diluted? 5. Why is it important to incubate the plates at a specific temperature for a certain length of time? 6. What are primary and secondary antibodies in the context of this assay? 7. Why is it necessary to incorporate washing steps in the assay? 8. Describe the signaling system in this ELISA 9. Explain three limitations in this ELISA? 10. Describe the principle of quantification in an ELIS IMMUNOLOGY VIRTUAL LAB WORKSHEET