Question

DNA fragments separated by gel electrophoresis are shown. Mark the correct statement-

• A. Band 3 contains more positively charged DNA molecule than 1
• B. Band 3 indicates more charge density than 1 and 2
• C. Band 1 has longer DNA fragment than 2 and 3
• D. All the bands have equal length and charges but differ in base composition

Answer 1

The correct option is C Band 1 has longer DNA fragment than 2 and 3

Gel electrophoresis is a technique used to separate DNA fragments according to their size. DNA samples are loaded into wells at one end of a gel, and an electric current is applied to pull them through the gel.
DNA fragments are negatively charged, so they move towards the positive electrode. Because all DNA fragments have the same amount of charge per mass, small fragments move through the gel faster than large ones.

So, larger the fragment, slower will be the movement. Therefore, Band 1 will have larger DNA fragment than Band 2 and 3.