Difference between rDNA and cDNA

rDNA and cDNA are two modified molecules of DNA that are useful in new throughput DNA technologies. cDNA or complementary DNA are synthesised by the reverse transcription of mRNAs, whereas rDNA or recombinant DNA are synthesised by joining at least two DNA fragments from different sources.

Let us look at the differences between rDNA and cDNA in the table below.




rDNA or recombinant DNA is formed by joining together two DNA fragments from two different sources.

cDNA or complementary DNA are formed by the reverse transcription of mRNAs.

Enzymes Required

Restriction enzymes and ligases are required to synthesise rDNA.

Reverse transcriptases are required to synthesise cDNA.


It can only be synthesised artificially, outside the cell.

It can be synthesised both naturally and artificially.


Recombinant DNA are useful in synthesising recombinant proteins that are used in various pharmaceutical products.

It is used in gene cloning, creation of cDNA library, in PCR and RT-PCR.

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Frequently Asked Questions

What is the difference between rDNA and DNA?

rDNA is artificially synthesised by joining two or more DNA fragments from different sources, whereas DNA is a naturally occurring molecule in cells.

Why is cDNA used instead of mRNA?

cDNA is used instead of mRNA because it does not contain introns or any genomic DNA that might hinder the technology being performed.

What is the difference between cDNA and gDNA?

gDNA or genomic DNA consists of introns and exons whereas cDNA or complementary DNA consists only of exons.

Is cDNA complementary to mRNA?

Yes, the cDNA is complementary to the mRNA strand.

Can you run cDNA on a gel?

Yes, you can run cDNA on a gel but it tends to form smears rather than clear bands.

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