Deck 17: Lymphocyte Maturation and Expression of Antigen Receptor Genes

Question 1

Which of the following is NOT a property of the V(D)J recombinase?

A) Recognizes specific DNA sequences flanking gene segments in the antigen receptor gene loci
B) Introduces double-stranded nicks in the DNA between recombination signal sequences and the adjacent V, D, or J coding sequences
C) Promotes joining V-to-J, D-to-J, and V-to-D
D) Repairs double-stranded DNA breaks
E) Splices out intronic sequences from primary RNA transcripts

Answer 1

Splices out intronic sequences from primary RNA transcripts

Question 2

Which of the following statements about negative selection during lymphocyte development is most accurate?

A) The mechanism of negative selection is the death of cells whose antigen receptors are not stimulated by self antigens.
B) The mechanism of negative selection is apoptosis actively induced by antigen-receptor recognition of self antigens.
C) Negative selection ensures a self MHC restricted repertoire of T lymphocytes.
D) Negative selection occurs only in T cell maturation and not in B cell maturation.
E) The major mechanism of negative selection is inhibition of antigen receptor expression.

Answer 2

The mechanism of negative selection is apoptosis actively induced by antigen-receptor recognition of self antigens.

Question 3

The figure depicts the germline organization of gene segments of the Ig heavy chain locus on chromosome 14.
Choose the lettered label on the figure (A-E) that best matches the description in questions .

A segment that encodes Ig-like domains that form part of the antigen-binding region of an Ig molecule

Answer 3

A
One variable (V) gene segment, from as many as 45 possible V gene segments, is used in each functional Ig heavy chain gene
This V gene segment encodes an Ig domain that includes complementarity-determining regions (CDRs) 1 and 2 of the antigen-binding region of the heavy chain.

Question 4

The figure depicts the germline organization of gene segments of the Ig heavy chain locus on chromosome 14.
Choose the lettered label on the figure (A-E) that best matches the description in questions .

Encodes the isotype of antibodies made by naive B cells

Question 5

Which of the following is NOT an example of a checkpoint in lymphocyte maturation that contributes to the selective maturation of cells with useful antigen receptors?

A) B cell precursors that cannot express Ig g heavy chains die by apoptosis.
B) T cell precursors that cannot express TCR b chains die by apoptosis.
C) Immature B cells that bind to self antigen with high affinity die by apoptosis.
D) Developing T cells that fail to express TCR a chains die by apoptosis.
E) Developing T cells that recognize self major histocompatibility complex (MHC) molecules with high affinity die by apoptosis.

Question 6

Matching
The block in the stage of lymphocyte development described in questions , will be caused by a mutation in which of the genes listed (A-F)?
Pro-B cell to pre-B cell

A)
B)
C)
D)
E)
F)

Question 7

Matching
The block in the stage of lymphocyte development described in questions , will be caused by a mutation in which of the genes listed (A-F)?
Stem cell to committed B or T lineage precursor

A)
B)
C)
D)
E)
F)

Question 8

The figure depicts the germline organization of gene segments of the Ig heavy chain locus on chromosome 14.
Choose the lettered label on the figure (A-E) that best matches the description in questions .

A type of gene segment involved in somatic recombination events in Ig heavy chain and light chain as well as TCR a and b chain gene loci

Question 9

The figure depicts the germline organization of gene segments of the Ig heavy chain locus on chromosome 14.
Choose the lettered label on the figure (A-E) that best matches the description in questions .

Homologous segments of this type of gene segment that encode part of the third complementarity determining region (CDR3) of Ig heavy chains and TCR b chains but not Ig light chains or TCR a chains

Question 10

Which of the following is NOT a required step in B and T lymphocyte maturation?

A) Proliferative expansion of precursor cells
B) Cell surface expression of complete antigen receptor complexes
C) Positive selection
D) Activation of precursors by foreign antigens
E) Pre-antigen receptor expression

Question 11

Matching
The block in the stage of lymphocyte development described in questions , will be caused by a mutation in which of the genes listed (A-F)?
CD4+CD8+ thymocyte to single positive CD8+ thymocyte

A)
B)
C)
D)
E)
F)