Multiple choice

Three samples of antibodies were electrophoresed under denaturing and reducing conditions on a 15% acrylamide gel, followed by staining with Coomassie blue dye. Samples 1, 2 and 3 showed two, three and four stainable bands respectively. Which one of the following conclusions can be made from these observations?

  1. Sample 1 is IgG, 2 is IgA and 3 is lgM

  2. Sample 1 is IgA, 2 is 1gM and 3 is IgG

  3. Sample 1 is IgG, 2 is 1gM and 3 is IgA

  4. Sample 1 is IgA, 2 is IgG and 3 is 1gM

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

IgG is a monomer (2 chains: heavy and light), IgA can be a dimer (more bands), and IgM is a pentamer (multiple chains). The number of bands under reducing conditions corresponds to the number of distinct polypeptide chains.