What is the role of a DNA probe in fingerprinting?

• A. A DNA probe binds to complementary sequences to locate fragments
• B. It digests DNA
• C. It amplifies DNA in PCR
• D. It sequences DNA

Answer: (A)

In DNA fingerprinting, the DNA probe’s job is to locate specific DNA sequences by binding to their complementary sequences. After the DNA is cut and separated by size, the probe, which is labeled so it can be detected, hybridizes to fragments that contain the target sequence. This binding marks those fragments so they can be visualized (often on a membrane) and compared between individuals. The pattern of labeled bands is what distinguishes one person from another.

The other processes aren’t the probe’s role: digestion is done by restriction enzymes before probing, amplification is done by PCR to copy sequences, and sequencing reads the exact order of nucleotides rather than indicating where a particular sequence appears.