A student makes a new gel using agarose, water, and buffer solution. The student loads their DNA samples in their wells and places the gel in the chamber for an appropriate length of time. When the student places the gel on the UV lightbox, no DNA bands show up at all. Even the marker lane is clear and has no bands! What mistake did the student make? Explain your answer.

A dye needs to be added to the gel electrophoresis

Explanation:

Ethidium bromide (EtBr) is a reagent that adheres to DNA and fluoresces under ultraviolet (UV) light. Due to this feature, EtBr is widely used to dye DNA strands in molecular biology techniques such as agarose gel electrophoresis. The most common dyes for visualizing and staining nucleic acids during gel electrophoresis include EtBr, SYBR gold, Eva green and SYBR safe. If EtBr (or any other staining agent) was not added to the electrophoresis gel and/or running buffer, the gel will be dark under UV light (even the ladder lane will look empty) because DNA has not been stained.