Question

Select the true statements about SDS-PAGE, a method of separating proteins. Assume that SDS-PAGE is performed under reducing conditions. Proteins are separated in a polyacrylamide gel matrix. Sodium dodecyl sulfate binds proteins, resulting in protein-SDS complexes that are similar in size. Protein-SDS complexes migrate toward the negative electrode. Smaller proteins migrate faster through the polyacrylamide gel. Proteins are visualized using a dye that binds to the gel matrix, but not to proteins. Protein-SDS complexes have similar mass to charge ratios; therefore, separation is by size.

Answer 1

The correct statements are:-

1. Proteins are separated in a polyacrylamide gel matrix

4. Smaller proteins migrate faster through the polyacrylamide gel

6. Protein- SDS complexes have similar mass to charge ratios, therefore separation is by size

• That is one SDS molecule binds to 2 amino acids on average. Mass is almost similar.

2,3 and 5th statements are incorrect.

2nd statement is incorrect because protein-sds complexes vary in size and the separation of proteins occur on account of the size of the proteins. As smaller proteins will move faster in the current.

3rd statement is wrong because protein-sds complex move towards the positive anode. Protein-sds complex are highly negatively charged.

5th statement is wrong because dye binds to proteins and that's how the proteins are tracked according to their movements in the gel matrix.