Question

Match sequencing methods with key feature. 

• A. A-1, B-2, C-3, D-4
• B. A-2, B-1, C-4, D-3
• C. A-3, B-4, C-1, D-2
• D. A-4, B-3, C-2, D-1

Hint:

Key associations for sequencing tech: Sanger = ddNTPs/termination. Illumina = Reversible terminators/fluorescence SBS. Nanopore = Current/electrical changes. Pyrosequencing = Pyrophosphate/Luciferase light flash.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
DNA sequencing technologies have evolved significantly through multiple generations over the decades.
Each distinct platform relies on a unique biochemical or physical principle to accurately read the sequence of nucleotides.

Step 2: Detailed Explanation:
Let's pair each sequencing method with its defining technical feature.
- Sanger sequencing (A): Also known as the dideoxy method, this first-generation technique relies on the incorporation of dideoxynucleotides (ddNTPs) during DNA replication.
The absence of a 3'-OH group on the ddNTPs causes immediate chain termination.
Thus, A matches with 1.
- Illumina sequencing (B): This is the currently dominant next-generation sequencing (NGS) platform.
It is characterized as Sequencing by synthesis (SBS), where fluorescently labeled, reversibly terminating nucleotides are incorporated and imaged one by one.
Thus, B matches with 2.
- Nanopore sequencing (C): This is a third-generation, long-read sequencing method where single-stranded DNA is drawn through a tiny protein pore.
Changes in the electrical signal (ionic current) as different specific bases pass through the pore are measured and translated into a sequence.
Thus, C matches with 3.
- Pyrosequencing (D): This is an early NGS method that sequences by synthesizing the complementary strand.
It relies on the detection of pyrophosphate release upon nucleotide incorporation, which triggers an enzymatic cascade resulting in a flash of luminescence (light detection).
Thus, D matches with 4.

Step 3: Final Answer:
Matching these gives the precise sequence: A-1, B-2, C-3, D-4.
This corresponds directly to option (A).