Test Bank For Immunobiology 9th Edition By by Kenneth Murphy

Test Bank For Immunobiology 9th Edition By by Kenneth Murphy

Janeway’s Immunobiology, 9^th Edition

Chapter 5: The Generation of Lymphocyte Antigen Receptors

Primary immunoglobulin gene rearrangement

5-1  Immunoglobulin genes are rearranged in the progenitors of antibody-producing cells

5.1 Multiple choice: The exon encoding the V region of an immunoglobulin protein is generated by a process of somatic recombination. This recombination event brings V gene and J gene segments together:

A.  In all cells of the body to encode a V region sequence

B.  To generate maximum diversity in the CDR3 sequence of the V region

C.  By alternative RNA splicing to encode a V region sequence

D.  By a precise mechanism that never adds or loses nucleotides at the junction

E.  To generate a single exon encoding the entire immunoglobulin protein

5-2  Complete genes that encode a variable region are generated by the somatic recombination of separate gene segments

5.2  True/False: Most eukaryotic genes are encoded in a set of exons that are brought together to form a contiguous protein coding sequence by the process of mRNA splicing. In contrast, immunoglobulin genes use somatic recombination of gene segments and not mRNA splicing to generate the final mRNA that is translated into protein.

5-3  Multiple contiguous V gene segments are present at each immunoglobulin locus

5.3  Multiple choice: Different individuals can have different numbers of functional V gene segments as well as different numbers of constant region genes. This type of genetic polymorphism between individuals indicates that:

A.  The antibody heavy and light chain loci undergo more frequent mutation than other genes in the genome.

B.  The recombination machinery is active in germ cells.

C.  Individuals only need κ or λ light chains, but not both.

D.  The precise number of antibody gene segments in an individual is not important.

E.  Antibody gene segments underwent more frequent duplication during evolution than other genes in the genome.

5-4  Rearrangement of V, D, and J gene segments is guided by flanking DNA sequences

5.4  Multiple choice: Recombination signal sequences are conserved heptamer and nonamer sequences that flank the V, J, and D gene segments which undergo recombination to generate the final V region coding exon. Some of these have 12-nucleotide spacers between the heptamer and nonamer, and others have 23-nucleotide spacers. The reason recombination signal sequences come in these two forms is:

A.  To ensure the correct assembly of gene segments so that a V_H recombines to a D_H and not to another V_H, for instance

B.  To ensure that the heptamer and nonamer are found on the same face of the DNA double helix

C.  To ensure that κ, λ, and heavy chains recombine within a locus and not between loci

D.  To ensure that κ, λ, and heavy chain gene segments do not undergo recombination with non-immunoglobulin genes

E. To ensure that the RAG recombinase cuts the DNA between the last nucleotide of the heptamer and the coding sequence

5-5  The reaction that recombines V, D, and J gene segments involves both lymphocyte-specific and ubiquitous DNA modifying enzymes

5.5  Figure Q5.5 shows the germ-line configuration of three V gene segments (#1, 2, 3), and two J gene segments (#4, 5). Which of the choices below represents a DNA configuration that would result from V-to-J recombination?