Question

1. This pathway to complement activation can be initiated by several different signals including the properdin/factor P activation pathway

   1. The classical pathway

   2. The alternative pathway

   3. Lectin pathway

   4. All of the above

2. The mechanism that permits Ig to be synthesized in either a membrane-bound or secreted form is:

   2. Allelic exclusion

   3. Codominant expression

   4. The one-turn/two-turn joining rule

   5. Differential RNA processing

3. Which of the following allows for recombination in the V(D)J coding regions?

   3. IL-2b

   4. TdT

   5. RAG-½

   6. All of the above

4. Generation of combinatorial diversity within the variable regions of Ig involves all of the following EXCEPT:

   4. mRNA splicing

   5. DNA rearrangement

   6. Recombination signal sequences

   7. one-turn/two-turn joining rule

5. Which of the following accounts for allelic exclusion in rearrangement of heavy chain genes?

   5. Rearrangement occurs on one allele at a time and id successful the other allele is silences

   6. Rearrangement is regulates by TdT which is only expressed during rearrangement

   7. Both alleles rearrange simultaneously and undergo repeated rearrangement until one succeeds

   8. If both alleles successfully rearrange the cel divides so each daughter cell gets one allele

6. If a BCR is autoreactive this process allows for additional recombination of the light-chain gene giving some chance a version that is not autoreactive may result.

   6. Class switching

   7. Receptor editing

   8. Alternative polyadenylation

   9. Somatic hypermutation

7. All of the following with respect to MHC proteins are true, EXCEPT:

   7. MHC form grooves that allow the presentation of many different peptides

   8. MHC are only expressed when pattern recognition receptors detect foreign material

   9. The MHC on a single cell often contain many different peptides

   10. Only a limited number (not all) of the amino acid residues in a peptide need to bind the MHC grooves

8. Which class of professional antigen presenting cell, APC, expresses class II MHC molecules and a costimulatory signal constitutively?

   8. B cells

   9. Dendritic cells

   10. Macrophages

   11. T cells

9. Your chance of having the same MHC haplotype a sibling (brother or sister) is:

   9. 100%

   10. 50%

   11. 25%

   12. 10%

10. B-cell receptor expression progresses as follows:

    10. Successful heavy chain allele recombination results in a pre-BCR

    11. Successful light chain allele recombination results in a pre-BCR

    12. Both heavy and light chain alleles must each recombine to form a pre-BCR

    13. Formation of a pre-BCR signals the start of recombination of receptor genes

Answer 1

1. The answer is b. Alternative pathway

Explaination:

The factor P which represents properdin, factor B and factor D are the three components of alternative pathway to complement activation.

Properdin is an initiator of alternative pathway and stabilizes C3 and C5 convertase which leads to the enhancement of activity of alternative pathway.

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2. The answer is d. Differential RNA processing.

Explaination:

RNA processing involves the removal of introns, addition of polyA tail and capping of mRNA.

Differential RNA processing involves the removal of one of the exons in some cells forms a closely related member of the family of immunoglobulin which may be either membrane bound or secreted form.

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3. The answer is c. RAG 1/2

Explaination:

The proteins RAG1 and RAG2 codes for enzyme recombinase. It allows the VDJ recombination which means assembly of variable gene, diversity gene and joining gene by T and B cells.

It occurs in lymphoid organs. Bone marrow for B cells and thymus for T cells.

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4. The answer is RNA splicing.

Explaination

Generation of combinatorial diversity involves DNA rearrangements, recombination signal sequences and one turn two turn joining rule.