For each of the following characteristics, will the migration of the protein speed up, slow down, or remain unchanged if you do not add SDS?

a)increase molecular weight of protein
b) increase concentration of acrylamide
c)decrease charge on protein
d) increase surface area of protein

To determine if the migration of a protein will speed up, slow down, or remain unchanged if SDS is not added, we need to understand the role of SDS in protein migration during gel electrophoresis.

SDS (Sodium Dodecyl Sulfate), a detergent, is commonly added to protein samples during gel electrophoresis to denature the proteins and give them a uniform negative charge. This ensures that the separation of proteins in the gel primarily depends on their molecular weights.

Now let's analyze each characteristic one by one:

a) Increase in molecular weight of protein:
If the molecular weight of a protein increases, its migration speed will slow down because larger proteins experience more resistance while passing through the pores in the gel. Therefore, in the absence of SDS, an increase in molecular weight of the protein would still result in a slower migration.

b) Increase in concentration of acrylamide:
Acrylamide concentration affects the size of the pores in the gel. Higher acrylamide concentrations create smaller pores, leading to a slower migration of proteins. So, even without SDS, if the acrylamide concentration increases, the migration of the protein would slow down.

c) Decrease in charge on protein:
Charge is not directly affected by the addition of SDS since it primarily denatures and unfolds the proteins. Without SDS, if the charge on the protein decreases, it would not have a significant impact on the migration speed. The migration of the protein may remain unchanged.

d) Increase in surface area of the protein:
An increase in the surface area of the protein would not have a direct impact on migration speed. The separation in gel electrophoresis is primarily based on the size of the proteins, rather than their surface area.

In summary, without the addition of SDS, the migration speed of a protein will primarily be influenced by its molecular weight and the concentration of acrylamide in the gel. The charge on the protein and its surface area may have minimal to no impact on the migration speed.