Antigen binding Fab region Fe region- Heavy chain Hinge region Secretory component J chain 5. Shown on the left is an image of an IgA antibody dimer. The disulfide bonds are indicated in RED. Each blue rectangle (heavy chain) is 37 kDa, each green rectangle is (light chain) is 15 kDa. The J chain is 18 kDa and HOLDS together the two dimers and the secretory component is 67 kDa. Based on this information: a. What will be the size of IgA in size exclusion chromatography? WHY? b. What will be the size of IgA in SDS-PAGE when you ADD beta-mercaptoethanol? How many bands will you see on a gel? WHY? C. What will be the size of IgA in SDS-PAGE when you DO NOT ADD beta-mercaptoethanol? How many bands will you see on a gel? WHY? (9 points) Light chain 2 bonus points: what does IgA do in real life?