But unlike DNA replication, transcription needs no primer to initiate the process. Both replication and transcription proceeds in the 5′ → 3′ direction. In replication, the enzyme involved is DNA polymerase whereas in transcription the enzyme is RNA polymerase. In transcription, base pairings are adenine-uracil (AU) and guanine-cytosine (GC). In replication, the complementary base pairing includes the adenine-thymine (AT) and the guanine-cytosine (GC) base pairings. However, the output of replication is an exact copy of DNA whereas in transcription the output is not an exact copy but an mRNA transcript where thymines are replaced by uracils. Thus, transcription is regarded as the first step of gene expression and protein biosynthesis.īoth transcription and replication are biological processes of producing a copy of DNA. This transcript serves as a template for the next step of protein biosynthesis, translation, through the help of the enzyme, RNA polymerase. a copy of the coding sequence for a particular protein) is produced, generally by transcribing the template strand of the DNA. Transcription is a biological process wherein the mRNA transcript (i.e. capping, polyadenylation, and splicing) ensue. In eukaryotes, post-transcriptional events (e.g. Finally, hydrogen bonds of the RNA-DNA helix break in order to release the newly synthesized mRNA transcript. RNA sugar-phosphate backbone forms on the RNA strand. RNA polymerase adds RNA nucleotides as it traverses the DNA template. RNA polymerase, then, escapes the promoter. Abortive initiation causes the formation and the release of small RNA products. A transcription bubble forms, opening the DNA strand and exposing a segment that will be transcribed. During initiation, RNA polymerase binds to the promoter region of the DNA. The general steps are initiation, promoter escape, elongation, and termination. Transcription is a biological process wherein a segment of the DNA is copied to mRNA. After this, the mRNA transcript that carries a copy of the coding segment of the DNA is brought to the ribosomal site for translation. It goes through polyadenylation, capping, and splicing. In eukaryotes, the mRNA transcript goes through further processing. In the last phase, the hydrogen bonds of the RNA-DNA helix break. The RNA polymerase escapes the promoter to proceed to the elongation step where mRNA transcript is formed while traversing the noncoding strand of the DNA. A phase of abortive cycles of short mRNA transcripts are produced and released. A site in the transcription bubble binds to the RNA polymerase. This causes the part of the DNA to unwind and form a transcription bubble. In brief, the RNA polymerase together with certain transcription factors binds to the DNA promoter. The general steps of transcription are (1) initiation, (2) promoter escape, (3) elongation, and (4) termination. In eukaryotes, it takes place inside the nucleus. In prokaryotes, the process occurs in the cytoplasm. In biology, transcription is the process of transcribing or making a copy of the genetic information stored in a DNA strand into a complementary strand of RNA ( messenger RNA or mRNA) with the aid of RNA polymerases.
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