Understanding:
• Transcription occurs in a 5’ to 3’ direction
Transcription is the process by which a DNA sequence (gene) is copied into a complementary RNA sequence by RNA polymerase
- Free nucleotides exist in the cell as nucleoside triphosphates (NTPs), which line up opposite their complementary base partner
- RNA polymerase covalently binds the NTPs together in a reaction that involves the release of the two additional phosphates
- The 5’-phosphate is linked to the 3’-end of the growing mRNA strand, hence transcription occurs in a 5’ → 3’ direction
Direction of Transcription
Overview of Transcription
The process of transcription can be divided into three main steps: initiation, elongation and termination
- In initiation, RNA polymerase binds to the promoter and causes the unwinding and separating of the DNA strands
- Elongation occurs as the RNA polymerase moves along the coding sequence, synthesising RNA in a 5’ → 3’ direction
- When RNA polymerase reaches the terminator, both the enzyme and nascent RNA strand detach and the DNA rewinds
Many RNA polymerase enzymes can transcribe a DNA sequence sequentially, producing a large number of transcripts
- In eukaryotes, post-transcriptional modification of the RNA sequence is necessary to form mature mRNA
Summary of Transcription
Transcription Animation