Lymphocyte Development-D2

Question 1

allelic exclusion

Answer 1

Developing B and T cells undergo VDJ rearrangement on only one
allele at a time. This process ensures that each cell will only express one unique
antigen receptor

Question 2

antibody repertoire

Answer 2

The number of distinct BCR and antibody specificities within an
individual. Having a diverse repertoire ensures the adaptive immune system is capable
of responding to a wide array of antigens

Question 3

antigen

Answer 3

Target of the adaptive immune system. Originally refers to antibodygenerating
substance, but also includes peptides that are recognized by T cells

Question 4

common lymphioid progenitor

Answer 4

Cell type arising from pluripotent stem cells and

capable of differentiating into B cells, T cells and NK cells

Question 5

MHC restriction

Answer 5

A given T cell will only recognize its antigen when bound to an MHC
molecule. CD4 T cells recognize peptide antigens presented on MHC class II, while
CD8 T cells recognize antigens presented on MHC class I

Question 6

negative selection

Answer 6

Developmental process in immature B cells and T cells that
results in apoptosis when the antigen receptor recognizes self antigens. Negative
selection is important for removing autoreactive lymphocytes from the repertoire

Question 7

positive selection

Answer 7

Developmental process in immature B and T cells resulting in the
survival of cells that express a functional antigen receptor. B and T cell precursors that
do not express an antigen receptor undergo apoptosis

Question 8

recombinase activating gene (RAG)

Answer 8

Enzyme required for VDJ recombination

Question 9

terminal deoxynucleotidyl transferase (TdT)

Answer 9

Enzyme that randomly incorporates
nucleotides between the V, D and J segments during recombination. TdT contributes to
“junctional diversity” of the antigen receptor repertoire

Question 10

tolerance

Answer 10

Non-responsiveness of the immune system to an antigen

Question 11

VDJ recombination

Answer 11

Process that produces the antigen receptor variable region in
developing B cells and T cells. Antigen receptor genes have several segments named
V (variable), D (diversity) and J (junction). During VDJ recombination, one of several D
segments joins one of the several J segments, with the intervening DNA removed.
Then, one of several V segments joins the newly formed DJ segment. This random
joining of gene segments contributes to repertoire diversity