L4

Question 1

Antibody

Answer 1

Y-shaped protein produced by B cells that binds to antigens, neutralizing them or marking them for destruction

Question 2

BCR (B Cell Receptor)

Answer 2

Membrane-bound antibody on B cells that recognizes antigens and initiates activation

Question 3

Antigen

Answer 3

Molecule recognized by antibodies or T/B cell receptors, often proteins, polysaccharides, or lipids

Question 4

Epitope

Answer 4

Specific part of an antigen bound by an antibody or T cell receptor

Question 5

Isotype

Answer 5

Class of antibody determined by the structure of its constant region (e.g., IgG, IgM, IgA, IgD, IgE)

Question 6

B cells

Answer 6

Recognize unprocessed native antigens directly via BCR and bind diverse molecular types

Question 7

T cells

Answer 7

Recognize processed peptide antigens presented on MHC molecules via TCR

Question 8

Fab region

Answer 8

Fragment antigen-binding region of an antibody responsible for antigen binding

Question 9

Fc region

Answer 9

Fragment crystallizable region of an antibody responsible for effector functions

Question 10

Hypervariability regions

Answer 10

Highly diverse regions in antibody or TCR variable domains forming antigen-binding sites

Question 11

V(D)J recombination

Answer 11

Process in B and T cells combining V, D, and J gene segments to create receptor diversity

Question 12

RAG1/RAG2

Answer 12

Enzymes initiating V(D)J recombination by cleaving DNA at recombination signal sequences

Question 13

Combinatorial diversity

Answer 13

Generated by random selection of V, D, and J gene segments during recombination

Question 14

Junctional diversity

Answer 14

Created by addition or deletion of nucleotides at junctions between gene segments

Question 15

Somatic hypermutation

Answer 15

Process introducing mutations in antibody genes to increase antigen-binding affinity

Question 16

Class-switch recombination (CSR)

Answer 16

Mechanism allowing B cells to switch antibody isotypes while maintaining specificity

Question 17

Allelic exclusion

Answer 17

Ensures only one allele of the immunoglobulin gene is expressed in a B or T cell

Question 18

IgM

Answer 18

Default antibody isotype produced first, with membrane-bound and secreted forms regulated by splicing

Question 19

Severe Combined Immunodeficiency (SCID)

Answer 19

Immune disorder caused by defective RAG genes, impairing recombination

Question 20

Central tolerance

Answer 20

Mechanism removing self-reactive B cells in the bone marrow through deletion or receptor editing