Question

The following characteristics describe the receptors of the adaptive immune system (TCRs and BCRs) EXCEPT:

a. Receptors with different specificities are present on a single cell to enable it to defeat different pathogens.

b. Their diversity exceeds trillions of different receptors.

c. TCRs and BCRs are generated by the same molecular mechanism (VDJ recombination), but they use their own separate gene segments.

d. Their diversity is established in the bone marrow (BCR) and, respectively, the thymus (TCR).

Answer 1

T cell receptors (TCRs) and B cell receptors (BCRs)are diverse and exceed trillions of of different receptors. The B cells generate this type of diversity by a DNA damage which is programmed and it changes the coding sequence of lymphocyte immune receptors.

The BCRs develop in bone marrow whereas TCRs develop in thymus. They are generated by VDJ recombination mechanism, which is unique of developing T and B lymphocytes. It involves somatic recombination and leads to formation of diverse antibodies and TCRs in B and T lymphocytes.

These receptors are present on different cells like B and T lymphocytes.

Hence option (a) is correct.