Describe the process of transcription

Transcription is the process by which genetic information encoded in DNA is copied into a complementary RNA molecule. It occurs in the nucleus of eukaryotic cells and in the cytoplasm of prokaryotic cells. The steps involved in transcription are as follows:

1. Initiation: RNA polymerase, the enzyme responsible for transcription, binds to the promoter region of DNA, which signals the start of a gene.
2. Elongation: RNA polymerase moves along the DNA strand, unwinding it and adding complementary RNA nucleotides to the growing RNA strand. The RNA polymerase reads the DNA template strand from 3′ to 5′ direction, and adds RNA nucleotides in 5′ to 3′ direction.
3. Termination: Once the RNA polymerase reaches the termination signal in the DNA sequence, it stops transcription and releases the newly synthesized RNA molecule.
4. Post-transcriptional processing: In eukaryotic cells, the pre-mRNA molecule undergoes processing to become mature mRNA. This includes the addition of a 5′ cap and a 3′ poly-A tail, as well as the removal of introns by splicing.

The resulting mRNA molecule can then leave the nucleus and enter the cytoplasm, where it serves as a template for translation by ribosomes to produce proteins.