Which describes coding for immunoglobulin molecules?

Which describes coding for immunoglobulin molecules?

• A. All genes are located on the same chromosome.
• B. L chain rearrangement occurs before H chain rearrangement.
• C. Four different regions are involved in coding of H chains.
• D. Lambda rearrangement occurs before kappa rearrangement.

Answer: (C)

Immunoglobulin heavy chains are built from four distinct gene regions that are brought together during development: variable (V), diversity (D), joining (J), and constant (C). The V, D, and J segments undergo somatic recombination to create the variable region of the heavy chain, which then pairs with a constant region to form the full heavy-chain coding sequence. This modular arrangement—four separate regions contributing to the heavy chain—best describes how the heavy chain is coded. The other statements don’t fit this pattern. All immunoglobulin genes aren’t on a single chromosome—the heavy-chain locus is on one chromosome while light-chain loci lie on others. Heavy chains rearrange before light chains, so the idea that light chains rearrange first is incorrect. For light chains, kappa typically rearranges before lambda, not the other way around, making that option inaccurate.

Immunoglobulin heavy chains are built from four distinct gene regions that are brought together during development: variable (V), diversity (D), joining (J), and constant (C). The V, D, and J segments undergo somatic recombination to create the variable region of the heavy chain, which then pairs with a constant region to form the full heavy-chain coding sequence. This modular arrangement—four separate regions contributing to the heavy chain—best describes how the heavy chain is coded.

The other statements don’t fit this pattern. All immunoglobulin genes aren’t on a single chromosome—the heavy-chain locus is on one chromosome while light-chain loci lie on others. Heavy chains rearrange before light chains, so the idea that light chains rearrange first is incorrect. For light chains, kappa typically rearranges before lambda, not the other way around, making that option inaccurate.