Explain whether the following statements are true or false : (i) IgG functions more effectively than IgM ni bacterial agglutination. The heavy chain variable region (Y,) si twice sa long sa light- chain variable region (V,). (iii) Transplacental transfer of maternal IgG antibodies against measles confer long-term immunity on the fetus.

Sourav PanSeptember 4, 2024

Answered

(i) IgG functions more effectively than IgM in bacterial agglutination.

• False. While IgG is highly effective in many immune responses, particularly in opsonization and neutralization, IgM is generally more effective in bacterial agglutination. IgM is the first antibody produced in response to an infection and is a pentamer, allowing it to cross-link multiple antigens and cause agglutination more effectively than the monomeric IgG.

(ii) The heavy chain variable region (V_H) is twice as long as the light-chain variable region (V_L).

• False. The heavy chain variable region (V_H) and the light chain variable region (V_L) are similar in length. Both V_H and V_L regions typically consist of approximately 110-120 amino acids. They each contribute to the antigen-binding site of the antibody, but the heavy chain includes additional constant regions that are not present in the light chain.

(iii) Transplacental transfer of maternal IgG antibodies against measles confers long-term immunity on the fetus.

• False. Maternal IgG antibodies can provide temporary protection to the newborn against measles, but this protection is not long-lasting. The transplacental transfer of maternal IgG provides passive immunity that typically lasts for several months, but it does not confer long-term immunity. The infant will eventually require active immunization, such as the measles vaccine, to develop long-term immunity.