3) 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 how the migration of a protein is affected by specific characteristics, we need to understand the principles of gel electrophoresis.

Gel electrophoresis is a technique used to separate and analyze proteins based on their size and charge. It involves applying an electric field to a gel matrix, commonly made of acrylamide, to move proteins through the gel.

To answer each part of your question:

a) Increase molecular weight of protein:
Without adding SDS (sodium dodecyl sulfate), an anionic detergent, the migration speed of the protein will remain unchanged. This is because the primary factor that determines the protein's migration in the gel is its size, rather than its molecular weight. Larger proteins generally move slower than smaller proteins through the gel matrix during electrophoresis.

b) Increase concentration of acrylamide:
Increasing the concentration of acrylamide in the gel matrix will typically slow down the migration of proteins. This is because higher acrylamide concentrations provide a denser network, resulting in increased resistance to protein movement.

c) Decrease charge on protein:
Without adding SDS, decreasing the charge on the protein will generally lead to slower migration. Proteins naturally carry charges, and during gel electrophoresis, proteins migrate towards the oppositely charged electrode. Therefore, reducing the charge on the protein will result in a weaker attraction, slowing down its migration through the gel.

d) Increase surface area of protein:
Without SDS, increasing the surface area of the protein will generally have little to no effect on its migration velocity. The primary determinants of a protein's migration are its size and charge, not its surface area. As long as the protein maintains its charge and size, the migration speed should remain relatively unchanged.

It's important to note that adding SDS to the gel or the protein samples is a common practice in many gel electrophoresis techniques. SDS denatures proteins, neutralizes their charges, and masks their inherent charges. This allows for separation based primarily on size, providing more accurate results.