hn RNA stands for

✅ Explanation: hnRNA stands for heterogeneous nuclear RNA. It represents the primary transcripts of eukaryotic genes, which are the initial RNA molecules synthesized from DNA. These transcripts are diverse in size and sequence, hence the term "heterogeneous." hnRNA undergoes various processing steps, including splicing, capping, and polyadenylation, to become mature mRNA, which is then translated into protein.

🔑Key Points :
-Transcription is the process of copying the genetic information from one strand of DNA onto the RNA.

✏️Transcription involves 3 basic steps:
-Initiation
-Elongation
-Termination
-In eukaryotes, the mRNA is formed is the form of heterogenous RNA (hnRNA).
-This hnRNA needs to go through some post-transcriptional modification processes to form the mature mRNA that can be translated into polypeptide.
-Initiation Factor – 
-In prokaryotic transcription, RNA polymerase enzyme binds at the promoter site of DNA with the help of sigma (σ) factor and initiates transcription.
-The sigma factor is also known as the initiation factor.
-Introns – 
-In eukaryotes, the primary transcribed RNA has both exons and introns and is known as the hn-RNA or heterogeneous nuclear RNA. 
-Introns are the non-coding sequence of RNA that are removed before RNA is translated.
-The exons are the part of RNA that translates to a protein.
-Splicing is the process of removing introns and the joining together of exons in the primary RNA transcript.
-This forms the mature RNA from the hn-RNA.
-Termination Factor – 
-Transcription termination is carried out by the Rho factor (ρ) that binds to the terminator site.
-When the Rho factor comes across the RNA polymerase enzyme, the RNA is unwound from the DNA.
-The nascent RNA is released along with the enzyme.
-The DNA double helix reforms and Rho protein dissociates, terminating the transcription process.
-Adenylate residue – 
-Polyadenylation is the process of adding about 200-300 adenylate residues to the 3'-end of the newly formed RNA.
-These residues form a poly-A tail at the 3'-end of the mRNA and thus, this process is also known as tailing.
-In an eukaryotic cell, the RNA molecules have the risk of being degraded by cytoplasmic enzymes when the RNA is transported from nucleus to cytoplasm.
-Polyadenylation helps in protecting the 3'-end of the coding sequence of the RNA from digestive enzymes.