The pore size in a polyacrylamide gel can be controlled by manipulating the ratio of (a) Acrylamide and TEMED (b) Acrylamide and Bis-acrylamide (c) Bis-acrylamide and SDS (d) Bis-acrylamide and APS

The pore size in a polyacrylamide gel can be controlled by manipulating the ratio of (b) Acrylamide and Bis-acrylamide.

Here's why:

Polyacrylamide gels are formed by the polymerization of acrylamide and bis-acrylamide. Acrylamide acts as the monomer and forms the linear chain, while bis-acrylamide acts as the cross-linker and forms bridges between the linear chains, creating a three-dimensional network.

The ratio of acrylamide to bis-acrylamide determines the pore size of the gel. A higher ratio of acrylamide to bis-acrylamide results in a gel with smaller pores, while a lower ratio results in a gel with larger pores.

This is because a higher amount of bis-acrylamide (the cross-linker) will create more cross-links, resulting in a denser network with smaller pores. Conversely, a lower amount of bis-acrylamide will create fewer cross-links, resulting in a less dense network with larger pores.

Therefore, by manipulating the ratio of acrylamide to bis-acrylamide, you can control the pore size of the polyacrylamide gel.

The other options (a, c, and d) are not correct because TEMED, SDS, and APS do not directly influence the pore size of the gel. TEMED and APS are catalysts that help initiate the polymerization process, while SDS is a detergent that is used in SDS-PAGE to denature proteins and give them a negative charge.