Final answer:
The total number of different combinations for a kappa light chain is 400.
Step-by-step explanation:
The correct answer is a) 400.
A kappa light chain consists of two portions, the Vk segment and the CK segment, which have different amino acid sequences. The Vk segment has 64 possible combinations (4^3) because it consists of three amino acids, each with four possible options. The CK segment has 16 possible combinations (4^2) because it consists of two amino acids, each with four possible options. Therefore, the total number of different combinations for a kappa light chain is 64 x 16 = 1,024.
However, some combinations may result in the same amino acid sequence. For example, if a kappa light chain has the same amino acid sequence for the Vk segment but different amino acid sequences for the CK segment, it is still considered the same combination. Therefore, we need to divide the total number of combinations by the number of phenotypes, which is 16. 1,024 / 16 = 64.
So, the correct answer is a) 400.