Question

Match List I with List II:

Choose the correct answer from the options given below:

• A. A-V, B-I, C-III, D-II
• B. A-IV, B-II, C-III, D-I
• C. A-IV, B-V, C-II, D-I
• D. A-II, B-I, C-V, D-III

Hint:

To quickly solve matching questions, look for the most unique pair.
The Sanger method is almost always associated with ddNTPs (dideoxy terminators).
Once you identify A-IV, you can often eliminate several options immediately.
Additionally, remember that S1 nuclease is the "single-strand specific" enzyme, which helps in identifying the second pair.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
This question requires matching various molecular biology techniques, enzymes, and molecules in List I with their corresponding characteristic properties, components, or functions in List II.
The topics covered include DNA sequencing (Sanger method), enzymatic degradation (Nuclease S1), transcription (Reverse transcriptase), and gene silencing (siRNAs).
Detailed Explanation:

• Sanger Method (A - IV):
The Sanger method, also known as the dideoxy chain termination method, is a gold-standard technique for DNA sequencing.
It relies on the use of dideoxynucleoside triphosphates (ddNTPs).
Unlike normal deoxynucleoside triphosphates (dNTPs), ddNTPs lack a $3'$-OH group on the pentose sugar.
When a ddNTP is incorporated into a growing DNA strand by DNA polymerase, it prevents the formation of a phosphodiester bond with the next incoming nucleotide, thereby terminating the chain.
By using labeled ddNTPs, researchers can determine the sequence of nucleotides in a DNA fragment.

• Nuclease S1 (B - II):
Nuclease S1 is an endonuclease purified from the fungus Aspergillus oryzae.
Its primary characteristic is its high specificity for single-stranded nucleic acids, including both single-stranded DNA and RNA.
It is widely used in molecular biology for "S1 mapping" to locate the ends of RNA transcripts, removing single-stranded overhangs from DNA fragments to create blunt ends, and for analyzing DNA-RNA hybrids.
It does not significantly degrade double-stranded DNA or double-stranded RNA under standard conditions.

• Reverse Transcriptase (C - III):
Reverse transcriptase is an enzyme that catalyzes the process of reverse transcription.
It is primarily found in retroviruses (like HIV).
The enzyme functions by using an RNA template to synthesize a complementary DNA (cDNA) strand.
This effectively converts RNA information into DNA, which is a crucial step in the life cycle of retroviruses and is also the basis for the RT-PCR (Reverse Transcription Polymerase Chain Reaction) technique used in diagnostics and research.

• siRNAs (D - I):
Small interfering RNAs (siRNAs) are short, double-stranded RNA molecules involved in the RNA interference (RNAi) pathway.
Once siRNAs enter a cell, they are processed and incorporated into a multi-protein complex known as the RNA-Induced Silencing Complex (RISC).
Within the RISC, the siRNA is unwound, and one strand (the guide strand) remains bound to the complex.
The RISC then uses this guide strand to find and bind to complementary mRNA molecules, leading to the degradation of the target mRNA or the inhibition of its translation, thereby silencing the specific gene.

Step 2: Final Answer:
Matching the components correctly:
A (Sanger method) matches with IV (ddNTPs).
B (Nuclease S1) matches with II (Single-stranded RNA/DNA).
C (Reverse transcriptase) matches with III (Conversion of RNA to DNA).
D (siRNAs) matches with I (RISC).
The sequence A-IV, B-II, C-III, D-I corresponds to Option (B).