what is the step which Rna is made?
The process of RNA synthesis, also known as transcription, can be divided into several steps:
1. Initiation: RNA polymerase binds to the promoter region on DNA, which marks the starting point for transcription. In bacteria, a sigma factor helps in identifying the promoter sequence, while in eukaryotes, transcription factors play a role in promoter recognition.
2. Elongation: The RNA polymerase unwinds the DNA double helix, allowing one of the DNA strands (the template strand) to be used as a template for RNA synthesis. The polymerase adds complementary RNA nucleotides (A, U, G, and C) to the growing RNA chain, following the base-pairing rules.
3. Termination: Transcription continues until a termination signal is reached, which signals the end of the RNA molecule. In bacteria, termination signals can be intrinsic or require additional termination factors. In eukaryotes, termination involves the recognition of specific sequences, followed by the dissociation of the RNA polymerase from the DNA.
4. Post-transcriptional processing (in eukaryotes): In eukaryotes, the initial RNA transcript, known as pre-mRNA, undergoes various modifications before becoming mature mRNA. These modifications include the addition of a 5' cap (a modified guanine nucleotide) at the beginning of the RNA molecule, the addition of a poly-A tail (a string of adenine nucleotides) at the end of the RNA molecule, and the removal of non-coding sequences called introns through a process known as splicing.
Overall, these steps lead to the synthesis of RNA molecules that are eventually translated into proteins (in the case of messenger RNA) or perform various functions directly (in the case of non-coding RNA).