What is prokaryotic transcription process?

 Prokaryotic transcription is the process by which genetic information stored in DNA is used to synthesize RNA in prokaryotic cells, which include bacteria and archaea. This process involves several steps:

Steps in Prokaryotic Transcription:

1. Initiation:  

                         The first step in transcription is the binding of RNA polymerase, the enzyme that catalyzes the synthesis of RNA, to the DNA. In prokaryotes, RNA polymerase recognizes specific DNA sequences called promoters, which are located upstream of the gene being transcribed. The promoter region contains the information that specifies which strand of DNA is to be transcribed, the starting point for transcription, and the direction of transcription.

2. Elongation:

                          Once the RNA polymerase is bound to the promoter, it unwinds the DNA double helix and begins to synthesize RNA. As the polymerase moves along the DNA, it adds complementary RNA nucleotides to the growing RNA chain in a process called elongation. The RNA molecule is synthesized in the 5' to 3' direction, meaning that the RNA polymerase reads the DNA template in the 3' to 5' direction.

3. Termination:  

                                  The final step in transcription is termination, which occurs when the RNA polymerase reaches the end of the gene being transcribed. In prokaryotes, there are two types of termination: rho-dependent and rho-independent. Rho-dependent termination requires a protein called rho to bind to the RNA transcript and cause the RNA polymerase to dissociate from the DNA. Rho-independent termination occurs when the RNA transcript forms a hairpin loop followed by a series of uracil (U) nucleotides, causing the RNA polymerase to fall off the DNA.

The resulting RNA molecule is called messenger RNA (mRNA) and serves as a template for protein synthesis during translation.

Post transcriptional modifications:

                                                                                Post-transcriptional modifications are changes that occur to the pre-messenger RNA (pre-mRNA) molecule after it has been transcribed from DNA but before it is mature mRNA. These modifications are important for the stability, processing, and functionality of mRNA. The main post-transcriptional modifications include:

Capping:

                   The addition of a 7-methylguanosine cap to the 5' end of the pre-mRNA. The cap helps protect the mRNA from degradation and promotes its translation.

Polyadenylation:

                               The addition of a poly(A) tail to the 3' end of the pre-mRNA. The tail consists of a string of adenine nucleotides and helps protect the mRNA from degradation, as well as facilitating the export of the mRNA from the nucleus.

Splicing:  

                   The removal of introns, non-coding sequences of DNA, from the pre-mRNA, and the joining of exons, the coding sequences of DNA, to form the mature mRNA. Alternative splicing can also occur, where different combinations of exons are spliced together to produce different mRNA variants.

Editing:  

                  The modification of nucleotides within the mRNA molecule. This can involve the deamination of cytosine to produce uracil or the conversion of adenosine to inosine. Editing can change the coding sequence of the mRNA and lead to the production of different protein isoforms.

These post-transcriptional modifications are tightly regulated and ensure that the mature mRNA is a high-quality template for protein synthesis.