Difference between Random Primers and Oligo dT

What is a Random Primer?

Random primer is a short sequence of DNA that amplifies the given target sequence (DNA or RNA). It is a mixture of all possible hexamer nucleotides. Also, it is a single-stranded sequence that does not show template-specificity. It can anneal with any type of RNA.

This primer is suitable for tRNA, rRNA, small RNA, mRNA, non-coding RNA, degraded RNA and even RNA with secondary structures.

What is Oligo dT?

Oligo dT is a short segment of the deoxy-thymidine nucleotide sequence. It is usually used as a primer for cDNA synthesis (reverse transcription). It initiates the synthesis of the first strand by annealing to the 3’ end of poly(A). Also, this primer is not suitable for RNA lacking poly-A tail or degraded RNA.

Difference between Random Primers and Oligo dT

Random Primers

Oligo dT

It is a primer mixture composed of random nucleobase sequences.

It is a short stretch of the deoxy-thymidine nucleotide sequence.

It can anneal to any RNA.

In anneals only to the poly-A tail of RNA.

Random primer is not template-specific.

Oligo dT is template-specific.

It can be used in DNA synthesis, probe synthesis, and reverse transcription of RNA (even without poly-A)

It is used in the synthesis of cDNA from mRNA.

Also Read: Difference between cDNA and Genomic DNA Library

Frequently Asked Questions on Difference between Random Primers and Oligo dT

What is a primer?

It is a short sequence of single-stranded DNA that is used to initiate the DNA synthesis process. They help in the amplification of the target sequence. Some chemically synthesised primers (oligonucleotides) are site-specific.

What is reverse transcription?

It is a process by which cDNA (complementary DNA) is synthesised using RNA. Reverse transcriptase enzyme, primer, and template strands play a vital role in this process. It is an opposite process to the transcription. In transcription, RNA is synthesised from DNA.

How are primers useful in PCR?

PCR (polymerase chain reaction) is used to make multiple copies of the desired gene. It employs two main components – the primer and the DNA polymerase. Here, the primer adheres to the complementary strand of DNA and forms a double-stranded template.

Extended Reading: Polymerase Chain Reaction

Keep exploring BYJU’S Biology for more exciting topics.

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