Question

Electronic Polymerase Chain Reaction (e-PCR) is a computational procedure that is used..

• A. to identify STS site within DNA sequences
• B. to identify EST site within DNA sequences
• C. to identify non-coding sequence site within DNA sequences
• D. to identify coding sequence site within DNA sequences

Hint:

Think of the "P-C-R" in e-PCR. It mimics the lab technique. PCR amplifies a specific site. In bioinformatics, that specific, unique, amplifiable site is called an STS. So, e-PCR finds STSs.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Electronic Polymerase Chain Reaction (e-PCR) is a bioinformatics tool that simulates the laboratory PCR experiment. In a lab, PCR uses a pair of short DNA primers to amplify a specific segment of a DNA template. e-PCR does the same thing computationally: it takes primer sequences and searches a large DNA sequence database (like a genome) to find segments that would be "amplified," meaning segments that are flanked by sequences matching the primers.
Step 2: Detailed Explanation:
The primary application of e-PCR is in genome mapping. A Sequence-Tagged Site (STS) is a short, unique DNA sequence (typically 200-500 base pairs) in a genome whose location and base sequence are known. STSs are defined by a pair of PCR primers that will amplify them. Therefore, e-PCR is used to search a new DNA sequence (e.g., a newly assembled contig) for the presence of known STSs. Finding an STS within a sequence allows that sequence to be anchored to a physical or genetic map of the chromosome.
Let's analyze the other options:
EST (Expressed Sequence Tag) is a short subsequence of a cDNA sequence, representing a gene that is expressed. While e-PCR could theoretically find them if primers were designed, its primary designed purpose is for STSs.
Identifying general non-coding or coding sites is too broad. e-PCR is a specific search for a site defined by a unique pair of primers, which is the definition of an STS.
Step 3: Final Answer:
The main purpose of e-PCR is to identify Sequence-Tagged Sites (STSs) within larger DNA sequences, which is crucial for mapping genomes.