Hi Mia

The synthesis of DNA from an RNA template, via reverse transcription, results in complementary DNA (cDNA). cDNA can then serve as template in a variety of downstream applications for RNA studies such as gene expression; therefore, cDNA synthesis is the first step for many protocols in molecular biology. cDNA are much easier to to handle than RNA.

Best regards Britta

First reason is to get a dramatic amount of target sequence for analyzing the expression levels. Therefore, we need to copy the target in high amounts. This is why polymerisation is Done. However, there are many step repeats in pcr , therefore a stable form of mRNA is required. complementary DNA serves as a stable template for q pcr experiments. Polymerisation requires an enzyme called Dna polymerase which uses double stranded DNA like a train railway to move . However, due to dna denaturation, single stranded cDNA can not serves as a rail for polymerase anymore. To fix the problem which is also not a problem because we can target the desired sequences , primers are designed specifically to the desired sequences. Each cycle of pcr duplicates the amount of target sequenc and pcr dyes such as Syber green binds them and give rise a shine.