Which technique is used to separate DNA fragments to create a DNA fingerprint?

• A. Sanger Sequencing
• B. Northern Blot
• C. Gel Electrophoresis
• D. PCR

Answer: (C)

Gel electrophoresis separates DNA fragments by size using an electric field in a gel, which is essential for visualizing and comparing DNA fragment patterns. After DNA is cut with restriction enzymes, you get fragments of varying lengths. When these fragments travel through the gel, smaller pieces move faster than larger ones, creating a band pattern that acts like a DNA fingerprint. By comparing the positions and number of bands between samples, you can identify similarities and differences that are characteristic of individuals or samples.

Other techniques don’t produce that size-based fragment pattern: Sanger sequencing reads the exact nucleotide order of a DNA segment, not a multi-fragment size pattern; Northern blot detects RNA transcripts; PCR amplifies specific DNA regions but doesn’t generate the broad fragment size pattern used for fingerprinting.