Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: Artifacts such as dye blobs, spikes and split peaks indicate poor quality of DNA profiles
Reason R: Artifacts always arise due to stand slippage during DNA amplification.
In the light of the above statements, choose the most appropriate answer from the options given below
DNA Profile Quality and Artifacts Analysis
This section evaluates the given Assertion (A) and Reason (R) regarding DNA profiling.
Assertion A: DNA Artifacts and Profile Quality
Assertion A states that artifacts like dye blobs, spikes, and split peaks indicate poor quality of DNA profiles.
- This statement is correct.
- Artifacts are undesirable features in a DNA profile that deviate from the expected pattern.
- Common artifacts include dye blobs (large, broad peaks), spikes (sharp, narrow peaks unrelated to true alleles), and split peaks (an allele peak appearing as two smaller peaks).
- These visual anomalies suggest problems during sample preparation, amplification, or detection, compromising the accuracy and reliability of the profile.
Reason R: Cause of DNA Artifacts
Reason R states that artifacts always arise due to strand slippage during DNA amplification.
- This statement is incorrect.
- The term "always" is inaccurate. Strand slippage is a primary cause of specific artifacts, such as stutter peaks (where a small portion of the repeat unit is missed or added during PCR), but it does not account for all artifacts.
- Other significant causes of artifacts include:
- Contamination of the sample.
- Inhibitors present in the sample affecting PCR efficiency.
- Degradation of the DNA sample.
- Instrumental issues (e.g., detector noise, laser problems).
- Problems with fluorescent dyes or primers.
- Since artifacts can arise from multiple sources, attributing them solely and universally to strand slippage is incorrect.
Conclusion
Analysis Summary:
- Assertion A is correct as artifacts demonstrably signal compromised DNA profile quality.
- Reason R is incorrect because strand slippage is only one of several potential causes of artifacts, not the exclusive cause.
Therefore, the most appropriate answer is that Assertion A is correct, but Reason R is not correct.
Selected Option: 3. A is correct but R is not correct
Important Questions from Molecular Biology Techniques
Which one of the following does NOT use RNA-sequencing?
Which one of the following statements related to molecular cloning procedures is INCORRECT?
Amongst the following, which one is the most appropriate strategy to sequence and assemble highly repeated regions of a genome?
Given below are statements related to various molecular techniques
A. During molecular cloning of DNA fragments, a vector and insert molecule digested with two different enzymes can never be ligated with each other.
B. Only 3' → 5' exonucleases and not 5' → 3' exonucleases can be used for digesting nucleic acids to generate blunt-ended fragments for cloning.
C. In Sanger's dideoxy sequencing method, each reaction consists of a mixture of three dNTPs and one ddNTP.
D. Self-ligation of a vector with compatible ends can be prevented by treatment with alkaline phosphatase.
Which one of the following options represents a combination of correct statements?
Given below are four DNA sequences and a set of forward and reverse primers for PCR amplification.
In the absence of any other factors such as (but not restricted to) Tm, length, percent GC, etc., which one of the above template-primers combinations would produce an amplified fragment?Sequence Primes A 5' ACAATCGT.....ACTAGTAC-3' FP: 5'-TGTTAG-3'
RP: 5'-TAGTAC-3'B 5' AGTCTTAG.....ATGCCAGT - 3' FP: 5'-AAGACT-3'
RP: 5'-ACTGGC-3'C 5' CTTGACTA.....GTACAGTCA-3' FP: 5'-CTTGAC-3'
RP: 5'-TGACTG-3'D D 5' GATCTAGC.....TCAAGCAGAC-3' FP: 5'-GATCTA-3'
RP: 5'-CAGACG-3'
