Yes, it is necessary. This will avoid DNA contamination in your Rna sample, thus not compromising the next steps of your research.

Yes, I believe it is necessary. As does @Olga Makarova and others, who answered a similar question posted back in 2015 as follows: "Yes, you need to treat your RNA samples with DNaseI before cDNA synthesis".

Hello Adelia Putri Magna Bela

Yes, it is necessary to treat RNA sample with DNase I before cDNA synthesis, otherwise genomic DNA contaminating RNA preparations will serve as a template in RT-PCR to produce a false positive signal from RT-PCR.

Secondly, RNase-free DNase I, is guaranteed not to contain any ribonucleases. DNase I has historically been prepared from bovine pancreas, which is one of the richest sources of RNase activity. Therefore, it is hard to obtain DNase I sufficiently free of RNase. So, you should use that product which specifies (RNase-free) DNase I.

Most RNA isolation kits and reagents that are provided do an effective job of removing contaminating genomic DNA. But certain downstream quantification methods like the qRT-PCR, can detect even minuscule amounts of genomic DNA and may cause problems in analysis.

You can always check whether your RNA sample is contaminated with genomic DNA by running a negative RT-PCR, meaning run a PCR using housekeeping gene primers without cDNA reverse transcription. If the PCR product is generated from an RNA sample that was not reverse transcribed (minus-RT control), then the product is amplified from contaminating genomic DNA. If you do not observe any band, you can conclude that your RNA sample is free of genomic DNA.

Best.

Yes, it is necessary to use RNase free DNase I because of the 2 things:

1. DNase I will degrade DNA contamination from your sample prior to PCR.

2. RNase will degrade the RNA from which you need to synthesize cDNA. Hence your DNase needs to be RNase free.

Best of luck.

Yes, DNase I (RNase-Free) is often necessary before cDNA synthesis to remove any contaminating genomic DNA from RNA samples, ensuring that only RNA is converted into cDNA.