Which type of gel is suitable for fragments in the range of 200-20,000 base pairs?

Agarose gel is the most suitable type of gel for separating DNA fragments in the range of 200 to 20,000 base pairs. This is because agarose, a polysaccharide derived from seaweed, forms a gel matrix that allows for efficient resolution of larger DNA fragments compared to other types of gels. Its relatively low percentage concentration can be easily adjusted to create larger pore sizes, which is ideal for accommodating the larger fragment sizes in that range.

Agarose gels provide a favorable combination of mechanical strength and porosity, facilitating effective electrophoretic mobility while maintaining the integrity of larger DNA fragments. This characteristic makes it a preferred choice for various applications such as DNA electrophoresis, where size-dependent separation is crucial.

In contrast, polyacrylamide gel is better suited for smaller fragments, typically in the range of 5 to 500 base pairs, due to its tighter matrix. Gelatin and cellulose do not offer the same resolution capabilities for DNA fragments and are not typically used for this purpose in molecular diagnostics.