Question

DNA fingerprinting is based on variation in

• A. Ribosomal RNA
• B. VNTRs
• C. tRNA genes
• D. Introns only

Hint:

Remember: \[ \boxed{\text{DNA Fingerprinting} \longrightarrow \text{VNTRs (Variable Number of Tandem Repeats)}} \] For modern forensic analysis, STRs (Short Tandem Repeats) are now more commonly used, but classical DNA fingerprinting is based on VNTRs.

Answer 1

The Correct Option is B

Concept: DNA fingerprinting is a molecular technique used to identify individuals based on unique variations present in their DNA. The technique was developed by Sir Alec Jeffreys in 1984. It mainly relies on highly polymorphic DNA sequences called Variable Number of Tandem Repeats (VNTRs).
• VNTRs are short DNA sequences repeated multiple times in tandem.
• The number of repeat units differs from one individual to another.
• These variations make every person's DNA fingerprint unique (except identical twins).
• DNA fingerprinting is widely used in forensic science, paternity testing and population genetics.

Step 1: Understand VNTRs.
VNTRs consist of repeated DNA sequences arranged one after another. Example: \[ \boxed{\text{ATCG-ATCG-ATCG-ATCG}} \] Different individuals possess different numbers of these repeated sequences, creating DNA polymorphism.

Step 2: Why are VNTRs useful in DNA fingerprinting?
Since the number of tandem repeats varies greatly among individuals, VNTR analysis produces unique DNA banding patterns. These unique patterns are compared during:
• Criminal investigations.
• Paternity and maternity testing.
• Identification of missing persons.
• Population and evolutionary studies.

Step 3: Eliminate the incorrect options.

• Ribosomal RNA is involved in protein synthesis.
• tRNA genes participate in translation.
• Introns alone are not the basis of DNA fingerprinting.
• VNTR polymorphism is the fundamental principle of DNA fingerprinting. Therefore, \[ \boxed{Option (B) is the correct answer. \]