What is the usual concentration range of agarose used in gels?
Agarose gel concentration determines pore size and resolving range. Common laboratory concentrations range from 0.7 percent for large 5 to 60 kb fragments to 2 percent for 100 to 3000 bp fragments. The typical routine range encompassing most plasmid analyses and restriction digests is 1 to 3 percent, balancing handling strength and resolution. Below 0.3 percent gels become too fragile, above 4 percent viscosity and EEO increase excessively. Thus 1 to 3 percent represents standard usage, though specialized applications may use 0.5 to 2.5 percent.
Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.