Difference between Transcription and Reverse Transcription

The key difference between both transcription and reverse transcription is that transcription is the encoding of DNA genome into the molecules of RNA, while reverse transcription is the encoding of the genome of RNA into the molecules of DNA. tRNA, mRNA or rRNA are produced at the time of transcription, while cDNA is synthesized at the time of reverse transcription.

Transcription

  • This step is considered to be the first step in the process of gene expression and is involved in the making of mRNA molecules to copy the sequence of DNA of a gene
  • The outcome of gene expression is a synthesis of a protein. Transcription is a process of the following steps – initiation, elongation, and termination.
  • In transcription, the key enzyme used is RNA polymerase, which uses a template of single-stranded DNA for the synthesis of a complementary mRNA strand
  • The enzyme operates in the 5’ to 3’ direction, thus the addition of new nucleotides to the 3’ terminal

Reverse Transcription

  • The process involves a range of enzymes referred to as reverse transcriptases, and is involved in the flow of genetic data
  • Also referred to as RNA-directed DNA polymerase, reverse transcriptase are enzymes encoded from the genetic content of the retroviruses catalyzing the transcription of the retrovirus RNA into DNA
  • This process of catalyzed transcription is the reverse process of regular cellular DNA transcription into RNA, and as a result, the names retrovirus and reverse transcriptase
  • Reverse transcriptase is a basic element of the RT-PCR (reverse transcription-polymerase chain reaction) too

Key Difference between Transcription and Reverse Transcription

The table below depicts the differences between Transcription and Reverse Transcription.

Transcription

Reverse Transcription

What is the phenomenon?

Copying genetic information stored in the DNA genome into a complementary RNA strand

The reverse process of normal transcription, wherein RNA template is copied for the formation of a molecule of cDNA in the retrovirus

Template used

DNA molecules

RNA

Where can it be seen?

Seen in eukaryotes and prokaryotes

Seen in retroviruses

Encodes for

Encodes DNA genome into RNA

Encodes RNA genome into cDNA

Occurrence in the cytoplasm of

Prokaryotes and nucleus in eukaryotes

Host

Primer

RNA polymerase does not use any primer

Lysyl tRNA serves as the primer

Enzyme involved

RNA polymerase

Reverse transcriptase

Application of its products

Used in protein synthesis

Its products are integrated into the genome of the host

Products formed

mRNA

cDNA (complementary DNA)

Role

Synthesis of mRNA molecule having the same genetic information of coding DNA strand that is later translated into a functional protein

Used by retrovirus, incorporating genes into the genome of the host. Used in research in identifying the coding DNA sequence, and in the preparation of cDNA libraries.

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