This set of Immunology Multiple Choice Questions & Answers (MCQs) focuses on “Mechanism of V(D)J Recombination”.
1. Where are the kappa gene segments located in humans?
a) Chromosome 22
b) Chromosome 2
c) Chromosome 14
d) Chromosome 18
View Answer
Explanation: Various chromosomes contain various genes and gene segments. The gene segments that make the kappa light chain are located in chromosome 2.
2. Where are the lambda gene segments located in humans?
a) Chromosome 22
b) Chromosome 2
c) Chromosome 14
d) Chromosome 18
View Answer
Explanation: The gene segments that make the lambda chain are located on chromosome 22. Whether the final light chain should be a lambda or kappa is decided during mRNA processing.
3. Where are the heavy chain gene segments located in humans?
a) Chromosome 22
b) Chromosome 2
c) Chromosome 14
d) Chromosome 18
View Answer
Explanation: In humans, the gene segments that make a heavy chain in an immunoglobulin are located on the chromosome 14. The location is not the same in other species, it varies.
4. Which of the following recombinations is associated with the V(D)J recombination mechanism?
a) Somatic recombination
b) Replicative recombination
c) Mitosis recombination
d) Transpositional recombination
View Answer
Explanation: V(D)J recombination involves somatic recombination which results in highly diverse immunoglobulins and T cell receptors.
5. V(D)J recombination mechanism is mediated by a diverse collection of enzymes called___________
a) V(D)J rearranging enzyme
b) V(D)J switching enzyme
c) V(D)J recombinase
d) V(D)J deubiquitinase
View Answer
Explanation: V(D)J recombination enzyme is mediated by V(D)J recombinase which is a collection of diverse enzymes which include transferases, nucleases, kinases and many more.
6. Which of the following are responsible for the specificity of V(D)J recombination?
a) RSSs and RAG 1
b) RSSs and RAG 2
c) RSSs and artemis nuclease
d) RSSs and TdT
View Answer
Explanation: In order to maintain the specificity of the V(D)J combination, V(D)J recombinase,through the activity of RAG 1, binds to the RSSs,Recombination Signal Sequences, flanking the gene segments.
7. What are the sequences that are present in RSSs?
a) Pentamer and Hexamer
b) Hexamer and Heptamer
c) Pentamer and Nanomer
d) Heptamer and Nanomer
View Answer
Explanation: RSSs are the sequences which have the consensus sequences, the heptamer and the nanomer sequences. These are os conserved nucleotides.
8. Which of the following is the heptamer sequence of RSSs?
a) ACACTGT
b) ACATGTG
c) CACAGTG
d) TGTCACA
View Answer
Explanation: Heptamer sequence of Recombination signal Sequences,RSSs have conserved nucleotides and its sequence is CACAGTG.
9. Which of the following is the nanomer sequence of RSSs?
a) ACAAAAACC
b) AGAAAAAGG
c) CACCCCCAA
d) GAGGGGGAA
View Answer
Explanation: Nanomer sequence of Recombination signal Sequences,RSSs have conserved nucleotides and its sequence is ACAAAAACC.
10. V(D)J recombination mechanism is a feature of the innate immunity system. True/False?
a) True
b) False
View Answer
Explanation: V(D)J recombination mechanism is associated with the adaptive immunity system. It is a defining feature of the adaptive immunity system.
11. RSSs help in _________ the V(D)J recombination mechanism.
a) Inhibiting
b) Regulating
c) Enhancing
d) Fluctuating
View Answer
Explanation: The RSSs, Recombination Signal sequences, play an important role in regulating the V(D)J recombination rule by recombining the sequences with the 12/23 rule.
12. V(D)J recombination mechanism is energetically neutral, i.e., it doesn’t need any ATP hydrolysis for the process. True/False?
a) True
b) False
View Answer
Explanation: V(D)J recombination doesn’t need any sort of energy for the recombination to happen. That is why this mechanism is known to be energetically neutral.
13. In P-addition, the nucleotides are inserted by __________
a) RAG 1
b) RAG 2
c) TdT
d) DNA repair enzymes
View Answer
Explanation: P-addition is a mechanism carried out by the DNA repair enzymes where they insert small palindromic nucleotide sequences to prevent the hairpin loop formed by overhanging nucleotides.
14. Which of the following enzymes is responsible for N-Nucleotide addition?
a) RAG 1
b) RAG 2
c) TdT
d) DNA repair enzymes
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Explanation: TdT, Terminal deoxynucleotidyl transferase, is a DNA polymerase which adds small conserved nucleotide sequences after the P-addition, to increase the diversity mostly.
15. The D gene segment is important because it falls in the_________region.
a) CDRs
b) Framework
c) Hinge
d) Constant
View Answer
Explanation: D gene segment is the extra segment found in heavy chain unlike in light chain. It is so important because it falls in the CDR region, increasing the diversity.
Sanfoundry Global Education & Learning Series – Immunology.
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