Gel Electrophoresis: Agarose concentrations

Concentrate on the concentration Agarose gels act as a molecular sieve to separate DNA strands based on their length, with shorter fragments having an easier time migrating than longer fragments. Higher concentrations of agarose will effectively slow down the migration of DNA fragments, while lower concentrations allow DNA to migrate faster. However, it’s important to remember that every experiment is different and the concentration of agarose should ideally be optimized based on the sizes of DNA fragments that are being separated. For very large DNA fragments, anything over 4000 bp in length, a 0.8% gel will allow for quicker migration. However, if you are trying to identify small DNA bands you might need a 1.5% or 2% gel for best results.