What is the Difference Between Random Primers and Oligo dT?

The main difference between random primers and oligo dT lies in their specificity and the type of RNA they can bind to. Here are the key differences:

1. Specificity: Random primers are not specific to any template, while oligo dT is specific to its template.
2. RNA binding: Random primers can bind to any type of RNA, such as tRNA, rRNA, small RNA, mRNA, non-coding RNA, degraded RNA, and even RNA with secondary structures. In contrast, oligo dT only anneals to the poly-A tail of RNA.
3. Length: Random primers are usually 6 nucleotides in length, also known as random hexamers. Oligo dT primers are composed of stretches of deoxythymidine, commonly 12-18 nucleotides long.
4. Applications: Random primers can be used for DNA synthesis, probe synthesis, and reverse transcription of RNA (even those without a poly-A tail). Oligo dT is used specifically for synthesizing cDNA from mRNA.

In summary, random primers are versatile and can be used with a variety of RNA types, while oligo dT primers are specifically designed for binding to the poly-A tails of mRNA. Random primers are suitable for reverse transcription of most RNA species, including degraded RNA, while oligo dT primers are only useful for full-length reverse transcription of RNA with poly(A) tails.

Comparative Table: Random Primers vs Oligo dT

Here is a table comparing random primers and oligo dT primers:

Both random primers and oligo dT primers are used in reverse transcription, but they have different annealing properties and specificity. Random primers can anneal to any RNA, while oligo dT primers are specific for the poly(A) tails of mRNA molecules. This difference allows random primers to be used for reverse transcription of various RNA types, while oligo dT primers are primarily used for cDNA synthesis from mRNA with poly(A) tails.