Question

DNA fingerprinting relies on identifying the number of

• A. Repetitive coding and noncoding long DNA sequences
• B. Non-repetitive noncoding long DNA sequences
• C. Repetitive coding short DNA sequences
• D. Repetitive noncoding short DNA sequences

Answer 1

The correct option is D Repetitive noncoding short DNA sequences

There are certain specific short sequences of DNA called Short Tandem Repeats (STRs) which are repeated many times in the genome of an individual. DNA fingerprinting relies on the identifying the number of these repeats, as this would be unique to each individual. These sequences are parts of the noncoding portions of the genome. When DNA fingerprinting was a relatively new technique, the sequences used were Variable Number Tandem Repeats (VNTRs), also known as minisatellites. They are structurally similar to STRs, with a few differences, and were successfully used for several years in forensic laboratories. However, they were found to have a few limitations such as the requirement of huge DNA samples, and even difficulties interpreting them. STRs gradually came to be recognised as more reliable sequences for DNA fingerprinting, as their results were also found to have better precision.