A 2% agarose gel is better for separating which type of DNA fragments compared to a 0.8% agarose gel?

A 2% agarose gel is indeed better suited for separating low molecular weight DNA fragments compared to a 0.8% agarose gel due to its finer pore structure. The percentage of agarose in the gel determines the size of the pores; higher percentages create smaller pores, which facilitates the effective separation of smaller fragments of DNA.

In the case of low molecular weight DNA, the smaller pore size of the 2% agarose allows for better resolution and visualization of these fragments during electrophoresis. Smaller fragments migrate more quickly through the pores of the gel, thus allowing for clearer distinction between bands of closely sized DNA pieces. Conversely, lower concentrations like 0.8% are more suitable for larger DNA fragments, as the larger pores will impede the migration of smaller fragments, leading to poor resolution.

This understanding explains the suitability of higher percentage gels for specific sizes of nucleic acids, making the selection of gel concentration crucial for effective DNA analysis.