Composition of primer is
**Core Concept**
The primer used in reverse transcription polymerase chain reaction (RT-PCR) is a synthetic oligonucleotide that is complementary to the 3' end of the viral RNA genome. This primer plays a crucial role in initiating the reverse transcription process.
**Why the Correct Answer is Right**
The correct primer is a specific oligonucleotide that is complementary to the 3' end of the viral RNA genome. During RT-PCR, the primer binds to the viral RNA and serves as a starting point for the reverse transcriptase enzyme to synthesize a complementary DNA (cDNA) strand. The primer is designed to be complementary to the viral genome, allowing the reverse transcriptase to accurately replicate the viral RNA into cDNA.
**Why Each Wrong Option is Incorrect**
**Option A:** This is incorrect because it does not match the specific sequence of the primer used in RT-PCR.
**Option B:** This is incorrect because it is not the correct primer sequence used to initiate reverse transcription.
**Option C:** This is incorrect because it is not the correct primer sequence used to initiate reverse transcription.
**Clinical Pearl / High-Yield Fact**
The primer used in RT-PCR is highly specific and must be complementary to the 3' end of the viral RNA genome to initiate accurate reverse transcription.
**Correct Answer: D. 3' end complementary primer**