Which of the following statements about the generation of B cell receptor (BCR) diversity is FALSE?Select one alternative:Rearrangement of the gene segments coding the variable region of light and heavy chains is the only process by which BCR diversity is generated.Animals have multiple copies of the gene segments that code for the variable region of the heavy and light chains.Rearrangement of the gene segments that code for the variable region of light and heavy chains is a random process.The variable region of the heavy chain is coded by the V, D and J gene segments.

Le bcr (b-cell receptor) reconnaitALes déterminants antigéniques séquentielsBLes déterminants antigéniques conformationnelsCLes antigènes seulsDLes antigènes en association à une molécule du cmhELes antigènes à l'état natif

T cell maturation and development of their antigen-specific receptors takes place in the . B cells mature in the where they also develop their specificity to a single antigen. This specificity in both B and T cells is made possible through genetic . The genes that code for the variable regions of both B and T cell receptors are cut and spliced during the process of both cells. Because genetic rearrangement occurs at the level of the rather than in the RNA following , the changes are permanent, resulting in each cell being capable of binding to a single antigen in a pool of up to 1018 possible variations. B cell receptors are that are comprised of four and have two identical antigen binding sites. The region of the immunoglobulin is embedded in the cell membrane, and the variable regions are facing outward in order to bind to their potential antigenic match. Unlike B cell receptors, T cell receptors are comprised of two polypeptides and have antigen binding site(s) that is exposed. Like B cell receptors, their specificity to a single antigen is determined any encounters with antigens.

When a B cell or T cell is stimulated by antigen, it divides, producing many identical copies of itself. This is an important part of the selection model.

Whichof the following processes in the differentiation of the B-cell lineage takesplace primarily in the lymph nodes (as opposed to the bone marrow)?1 pointremovalof the gene regions coding for the γ (G class) heavy chain constant domains synthesisof immunoglobulin membrane receptors with surrogate light chains up-regulationand initial transcription of the genes for Igα and Igβ allelicexclusion of κ genes in cells using a λ light chain gene N-nucleotideaddition at the junction of heavy chainV and D gene region

Whichof the following processes in the differentiation of the B-cell lineage takesplace primarily in the bone marrow (as opposed to the lymph nodes)?1 point removalof the gene regions coding for the mand δ heavy chain constant domains mutationdirected to the variable domain regions specifying the structures of the CDRloops negativeselection to remove B cells that recognize self-antigen activationof B cells by foreign antigen rearrangementof the genes that code for T-cell receptors