EWhat effects on apoptosis would you expect from a mutation

E)What effects on apoptosis would you expect from a mutation in caspase 3?

F)Why is class switching important in the process of B cell maturation?

Solution

E) Caspase-3 is an effector caspase, and is activated by extrinsic and intrinsic cell death pathways. It plays a central role in the execution phase of cell apoptosis. A caspase-3 mutation has been reported in the MCF-7 breast cancer cell line,132 suggesting the presence of caspase-3 mutation in human cancer tissues. There are several recent reports that have focused on the caspase-3 mutation in different cancers. Scientists investigated caspase-3 somatic mutation in several cancers. They compared healthy and malignant tissue from the same patients for caspase-3 somatic mutations.  They did not observe any evidence of mutations in normal samples from the same patients and concluded that the mutations had risen somatically. The mutations consisted of missense mutations, silent mutations, mutations in the introns, mutation in the 5\'-untranslated and 3\'-untranslated regions.

F) Immunoglobulin class switching is a biological mechanism that changes a B cell\'s production of immunoglobulin from one type to another, such as from the isotype IgM to the isotype IgG. During this process, the constant-region portion of the antibody heavy chain is changed, but the variable region of the heavy chain stays the same. Since the variable region does not change, class switching does not affect antigen specificity. Instead, the antibody retains affinity for the same antigens, but can interact with different effector molecules. Class switching occurs after activation of a mature B cell via its membrane-bound antibody molecule (or B cell receptor) to generate the different classes of antibody, all with the same variable domains as the original antibody generated in the immature B cell during the process of V(D)J recombination, but possessing distinct constant domains in their heavy chains.