Question

Homotetramer put through SDS page will weigh.

A) Four times its actual weight
B) Half its actual weight
C) Same as its actual weight
D) Double its actual weight

Answer 1

A homotetramer will weigh the c) same as its actual weight on an SDS-PAGE because the SDS only denatures the protein and imparts a negative charge but does not change its molecular weight.

Step-by-step explanation:

A homotetramer is a protein complex made up of four identical subunits. When subjected to SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis), a homotetramer is denatured, and the SDS binds to the proteins. As a result, the proteins are coated with SDS which gives them a uniform negative charge and denatures them, so they lose their tertiary and quaternary structure. However, the molecular weight of the protein is not changed by the SDS coating. This means that a homotetramer put through SDS-PAGE will weigh the same as its actual weight, which is the sum of the weights of its subunits.

Therefore, the correct answer is C) Same as its actual weight.