Question

Why do we need loading dye?

a) Because DNA is colorless
b) The sample might float out of the well
c) To know when to end electrophoresis
d) To add flavor

Answer 1

Loading dye is needed in gel electrophoresis for several reasons. It colors the DNA samples, prevents them from floating out of the wells, and contains a tracking dye for monitoring the progress of electrophoresis.

Step-by-step explanation:

Gel electrophoresis is a technique used to separate DNA fragments of different sizes. Usually, the gel is made of agarose, a polysaccharide polymer extracted from seaweed. Loading dye is needed in gel electrophoresis because it serves multiple purposes. Firstly, DNA is colorless, so loading dye is added to DNA samples to give them color, making it easier to visualize and track the movement of DNA molecules during electrophoresis. Secondly, because the gel is in a liquid state before solidifying, the loading dye helps to densify the samples and prevents them from floating out of the loading wells. Finally, loading dye contains a tracking dye, which migrates through the gel at a known rate, serving as an indicator for the progress of electrophoresis and helping determine when to end the process.