Question

Which of the following should be the same in identical twins?

(A) the set of antibodies produced

(B) the set of MHC molecules produced

(C) the set of T cell antigen receptors produced

(D) the set of immune cells eliminated as self-reactive

Short answer

(A) The option “the set of antibodies produced” is false.

(B) The option “the set of MHC molecules produced” is true.

(C) The option “the set of T cell antigen receptors produced” is false.

(D) The option “the set of immune cells eliminated as self-reactive” is false.

Step-by-step solution

Identical twins

Identical twins are obtained from a single zygote; hence, they share the same genes. Identical twins often possess the same gender.

Although they have similar DNA sometimes, they look slightly different due to environmental factors and womb position. Over time, behavioral and surrounding factors influence them to become more and more distinct.

Explanation of option (A)

Identical twins may have different antigens. Life habits alter the defense exhibited by the body. If identical twins are exposed to the same pathogen, they might produce antibodies with similarities. The set of antibodies produced in each individual is different.

Therefore, the set of antibodies produced in identical twins are not necessarily the same.

Thus, the given option is false.

Explanation of option (B)

Multiple amino acid substations cause unique MHC alleles in individuals. However, this uniqueness is an exception in identical twins due to their similar genes. The presence of similar DNA instructs the synthesis of similar amino acids in identical twins. Thus, the cells possess similar MHC molecules.

Therefore, the set of MHC molecules produced in identical twins are similar.

Thus, the given option is true.

Explanation of option (C)

T lymphocytes are creatively called T cell receptors. The process of formation of T cells is random. The region of the genome which instructs the formation of these molecules is complex. The process called V(D)J recombination forms a unique set of T cell receptors. It also depends on environmental factors.

Therefore, T cell receptors can overlap between identical twins but are not exactly similar.

Thus, the given option is false.

Explanation of option (D)

Thymus glands eliminate self-reactive immune cells during their production. The presence of such cells can cause autoimmune disease in the body. The immune cells are produced in the body as per the body naturally. Environmental factors distinguish identical twins.

Therefore, the elimination of self-reactive immune cells is not similar in identical twins.

Thus, the given option is false.