Write a paragraph describing the abbreviated chemical reactions that summarize RNA polymerase-directed transcription.

Verified step by step guidance

1. Begin by explaining that RNA polymerase-directed transcription is the process by which RNA polymerase synthesizes RNA from a DNA template strand.
2. Describe the initiation step where RNA polymerase binds to the promoter region of DNA, causing the DNA strands to unwind and expose the template strand.
3. Explain the elongation step, where RNA polymerase moves along the DNA template strand, adding ribonucleotides complementary to the DNA template, forming an RNA strand. This can be summarized by the reaction: \(\text{(DNA template)} + \text{rNTPs} \rightarrow \text{RNA} + \text{PPi}\), where rNTPs are ribonucleoside triphosphates and PPi is pyrophosphate.
4. Mention that the RNA strand grows in the 5' to 3' direction, with RNA polymerase catalyzing the formation of phosphodiester bonds between nucleotides.
5. Conclude with the termination step, where RNA polymerase reaches a termination signal on the DNA, causing the release of the newly synthesized RNA transcript and dissociation of RNA polymerase from the DNA.

Key Concepts

RNA Polymerase Function

RNA polymerase is the enzyme responsible for synthesizing RNA from a DNA template during transcription. It binds to the promoter region, unwinds the DNA, and catalyzes the formation of phosphodiester bonds between ribonucleotides, creating a complementary RNA strand.

Transcription Process and Directionality

Transcription proceeds in the 5' to 3' direction, where RNA polymerase reads the DNA template strand in the 3' to 5' direction. Ribonucleoside triphosphates (NTPs) are added sequentially, releasing pyrophosphate and forming the growing RNA chain.

Chemical Reaction of Nucleotide Addition

The core chemical reaction involves the nucleophilic attack of the 3'-OH group of the growing RNA chain on the α-phosphate of an incoming NTP. This reaction forms a phosphodiester bond and releases pyrophosphate (PPi), which is subsequently hydrolyzed to drive the reaction forward.