Final answer:
In an antibody, both of the light chains have to be of the same type: either both kappa or both lambda.
Step-by-step explanation:
In an antibody, both of the light chains have to be of the same type. This means that you can't have one kappa and one lambda chain in the same antibody molecule. A given antibody molecule in humans will have either both light chains as kappa or both of them as lambda, but never a mix of both. The question asks whether both light chains in an antibody have to be of the same type. The correct answer is that both light chains have to be of the same type, which means the statement is true. In other words, an antibody cannot have one kappa and one lambda light chain within the same molecule. Each antibody consists of two heavy chains and two light chains. The light chains can be of two types: kappa (κ) or lambda (λ). However, within a single antibody molecule, the light chains must be identical, so an antibody will have either two kappa or two lambda light chains but not one of each. This consistency is essential for the structural stability and function of the antibody. Based on the reference information, in humans, the proportion of kappa to lambda chains is about 2:1, with approximately 65% of light chains being kappa and 35% lambda. This ratio varies across different species, but the rule that a given molecule of immunoglobulin will only contain light chains of one type remains valid.