<prompt> An IgG2 molecule is composed of which of the following?One alpha, one gamma, and two kappa chainsOne gamma1 chain and two kappa chainsTwo gamma1 chains and one kappa and one lambda chainTwo gamma2 chains and two kappa chains  <response>: IgG molecules contain two gamma heavy chains of a given subtype and two light chains either kappa or lambda. The 2 in IgG2 indicates the subclass to which the molecule belongs. IgG2 contains two gamma2 chains since a given B cell can only form one type of heavy chain. The IgG molecule will contain either two kappa chains or two lambda chains, but never one of each. A given cell produces immunoglobulin molecules with a single type of heavy chain. IgG molecules with gamma1 chains would be of the IgG1 subclass. Ref: Levinson W. 2012. Chapter 58. Cellular Basis of the Immune Response. In W. Levinson Ed, Review of Medical Microbiology Immunology, 12e. 