Question

Which of the following statement is/are correct:
Statement (A): Expressed sequence tags are short sequences obtained by sequencing of cDNA clones.
Reason (B): ESTs can be used as STS.
In light of the above statements, choose the most appropriate answer from the options given below:

• A. Both (A) and (B) are correct.
• B. Both (A) and (B) are incorrect.
• C. Only (A) is correct but (B) is incorrect.
• D. Only (B) is correct but (A) is incorrect.

Hint:

ESTs represent the expressed portion of the genome (cDNA). Because they are unique, they are widely used as genetic landmarks (STSs) for physical mapping.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Expressed Sequence Tags (ESTs) and Sequence-Tagged Sites (STSs) are valuable molecular tools used in physical mapping and genome sequencing.

Step 2: Detailed Explanation:
Statement (A) is correct: Expressed Sequence Tags (ESTs) are short, single-pass sequence reads (typically 200 to 800 base pairs long) derived from the \(5'\) or \(3'\) ends of cDNA clones.
Because cDNA is generated from mature mRNA, ESTs represent expressed genes in a specific tissue at a given developmental stage.
Reason (B) is correct: A Sequence-Tagged Site (STS) is a short, unique sequence in the genome that can be easily identified and amplified by PCR.
Because ESTs are derived from unique expressed transcripts, they represent unique genomic sequences.
As a result, ESTs can be used as STSs (referred to as EST-derived STSs) for anchoring transcript maps onto physical genomic maps.
Both statements are biologically accurate and logically consistent with each other.

Step 3: Final Answer:
Hence, the correct option is (A).