Difference between RT PCR and qPCR

RT PCR

The RT PCR (Reverse Transcription Polymerase Chain Reaction) is a combination of reverse transcription and amplification process. Reverse transcription generates cDNA or complementary DNA of the specific target. This specific DNA is amplified using PCR (Polymerase Chain Reaction). Thus, it is predominantly used to detect the RNA transcript. This quantification of RNA can be done in two steps or even one step. In the two-step process, the cDNA formation and the amplification happen in separate tubes. In the one-step process, they are combined.

qPCR

The qPCR or real-time PCR is a polymerase chain reaction technique. It monitors the DNA during the amplification. Thus, it can be used both quantitatively and semi-quantitatively. This process is generally carried out in a thermocycler. Also, probes and fluorescent dyes can be used to mark the PCR products in every step.

Non-specific fluorescent dyes

These dyes get attached to the double-stranded DNA and give out signals as the amplification of DNA occurs. This is totally non-specific as they can attach to all double-stranded DNA.

Fluorescent-labelled DNA Probes

These probes are sequence-specific. They are usually detected after they are hybridised with their complementary sequence.

These PCR techniques are used for basic research as well as diagnostic purposes. Also, qPCR can be done without RT PCR and vice-versa.

Difference between RT PCR and qPCR

RT PCR

qPCR

It amplifies the specific DNA sequence.

It monitors the amplification process.

RT PCR uses RNA as a template.

Only RT-qPCR uses an RNA template.

It can be both qualitative and quantitative.

It is quantitative and semi-quantitative.

Frequently Asked Questions

What is a thermocycler?

Thermocycler or thermal cycler is an apparatus used to amplify DNA using polymerase chain reaction. The device has thermal block with holes where the samples are placed in tubes.

What is PCR?

Polymerase Chain Reaction or PCR is a technique used to make millions of DNA copies. A very small amount of specific DNA sample is amplified for study or diagnostic purposes. This method is dependent on the thermal cycling technique, where the reactants are exposed to repeated cycles of cooling and heating.

What is RT-qPCR?

RT-qPCR is a quantitative polymerase technique. Here, the starting template is RNA. This RNA is transcribed into cDNA, and then the qPCR process follows subsequently.

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