Quick revision: every question with its correct answer. For the full explanation, open the test and tap View Solution.
5.2 Antibody Diversity & V(D)J Recombination โ Test 1
Q1. During heavy-chain rearrangement, the first joining event is:โ D to J
Q2. The very first complete immunoglobulin expressed by a developing B cell is:โ Membrane IgM (the pre-B/immature B-cell receptor)
Q3. The surrogate light chain is used by the pre-B-cell receptor to:โ Test a successful heavy-chain rearrangement before light-chain assembly
Q4. Membrane IgM and IgD on a mature naive B cell are produced from a single transcript by:โ Alternative RNA splicing
Q5. Class-switch recombination is mediated by the enzyme:โ Activation-induced cytidine deaminase (AID)
Q6. Somatic hypermutation is also driven by which enzyme?โ Activation-induced cytidine deaminase (AID)
Q7. The double-strand DNA breaks created during V(D)J recombination are repaired by:โ Non-homologous end joining (NHEJ)
Q8. A productive (in-frame) rearrangement is one that:โ Maintains the correct reading frame and encodes a functional chain
Q9. Heavy- and light-chain pairing contributes to diversity because:โ Many different heavy chains can combine with many different light chains
Q10. In the rearrangement order, light-chain rearrangement begins only after:โ A productive heavy-chain rearrangement (signalled via the pre-BCR)
Q11. The coding joint formed in V(D)J recombination becomes part of the:โ Functional antigen-receptor gene
Q12. RAG-mediated recombination is restricted to lymphocytes because:โ RAG-1 and RAG-2 are expressed mainly in developing B and T cells
Q13. Receptor editing is a process in which a developing B cell:โ Re-rearranges its light-chain genes to change a self-reactive receptor
Q14. Compared with the heavy-chain locus, the kappa light-chain locus lacks:โ D segments
Q15. The estimated potential antibody repertoire is enormous because the diversity mechanisms are:โ Multiplicative (their effects combine)
Q16. Switch (S) regions are the DNA sequences that:โ Guide class-switch recombination upstream of constant-region genes
Q17. The combinatorial association of gene segments occurs at the level of:โ DNA (somatic recombination of segments)
Q18. A consequence of imprecise junctional joining is that:โ About two-thirds of rearrangements are non-productive (out of frame)
Q19. The signal joint produced during recombination is:โ Usually excised as a circular DNA and lost
Q20. The huge diversity of antibodies, despite limited genes, is achieved mainly by:โ DNA rearrangement (V(D)J recombination) and alternative splicing of transcripts
Q21. Junctional diversity of antibody and receptor genes results mainly from:โ Addition of P and N nucleotides at the joining sites
Q22. Match each enzyme/element with its role and select the correct option.โ A-ii, B-i, C-iv, D-iii