Which of following antibody is pentameric -

Ans. is 'a' i.e., IgM * Ig M is a pentameric immunoglobulin with five, four - peptide subunits.* The subunits are joined together by J chain.Remember* J chain is found in IgA and IgM.Also know* I think the following information requires some specific mention here-# There may be confusion about the status of momomer and dimer when applied to antibody as each molecule of an antibody is a dimer of two identical heavy and light chains.# But, the terms monomer , dimer or pentamer are used in context to how many molecules of same class of antibody are bound together-i) IgG is not found to bound to other IgG - Monomerii) IgA is bound to another IgA - Dimeriii) IgM binds four other IgM - Pentamer