DNA fingerprinting is based on possessing in DNA of
**Core Concept**
DNA fingerprinting is a technique used to identify individuals based on their unique genetic profiles. It relies on the variation in repetitive DNA sequences, known as short tandem repeats (STRs) or microsatellites, that are scattered throughout the genome.
**Why the Correct Answer is Right**
DNA fingerprinting is based on the presence of STRs, which are short sequences of 2-5 base pairs that are repeated multiple times in a row. These repeats are highly variable and are inherited in a Mendelian manner, making them ideal for identifying individuals. The technique involves amplifying these STRs using PCR and then separating them by size using gel electrophoresis. The resulting pattern of bands is unique to each individual, much like a fingerprint.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because DNA fingerprinting is not based on the presence of a single gene or protein, but rather on the variation in repetitive DNA sequences.
**Option B:** This option is incorrect because DNA fingerprinting does not rely on the presence of a specific gene or gene mutation, but rather on the variation in STRs.
**Option C:** This option is incorrect because DNA fingerprinting is not based on the presence of a specific virus or pathogen, but rather on the unique genetic profile of an individual.
**Clinical Pearl / High-Yield Fact**
Remember that DNA fingerprinting is a powerful tool for identifying individuals, but it can also be used to identify the source of a biological sample, such as a crime scene sample or a tissue sample from a transplant recipient.
**Correct Answer: D. Short Tandem Repeats (STRs)**