Question

Why can we see DNA bands on the gel electrophoresis?

1) Because there is DNA present in the gel
2) Because there is RNA present in the gel
3) Because there are proteins present in the gel
4) Because there are carbohydrates present in the gel

Answer 1

DNA bands are visible on gel electrophoresis due to the presence of DNA fragments that have been separated by size and visualized using a DNA-specific fluorescent dye. The correct option is 1) Because there is DNA present in the gel

Step-by-step explanation:

We can see DNA bands on the gel electrophoresis because DNA is present in the gel. During gel electrophoresis, DNA fragments are separated by size through a gel matrix.

The gel matrix acts somewhat like a sieve, allowing smaller fragments to move faster and farther than larger ones when an electric field is applied. DNA has a net negative charge due to the phosphate groups in its backbone, so it moves from the negative electrode towards the positive electrode.

After separation, the DNA fragments can be visualized using a fluorescent dye specific for DNA, such as ethidium bromide, which intercalates within the DNA strands and glows under ultraviolet light. This process results in visible bands on the gel, where each band represents DNA molecules of a specific size. The correct option is 1) Because there is DNA present in the gel