Which of the following processes does not occur in prokaryotes?

✅Explanation: Splicing is the removal of introns from pre-mRNA and joining of exons to form mature mRNA. Prokaryotic genes lack introns, so splicing does not occur.

📌 Other Options Explanations:
-(A) Transcription: The process of copying DNA into RNA, which occurs in both prokaryotes and eukaryotes.
-(C) Translation: The process of synthesizing proteins from mRNA, which occurs in both prokaryotes and eukaryotes.
-(D) Replication: The process of duplicating DNA, which occurs in both prokaryotes and eukaryotes.

🔑Key Points:
-The 3' end of the intron is marked as the splicing acceptor site or the 3' splice site.
-The highly conserved sequences for splicing are all found within the intron.
-None of the consensus sequences are found within the exons.
-In the transesterification reaction, two phosphodiester bonds are broken and two new ones are made.
-The net energy requirement is zero, hence it is an ATP independent reaction.
-In general splicing, a lariat structure is formed but in trans splicing, a Y shaped branched structure is formed.
Steps of intron splicing –

✏️Recognition:
-The spliceosome identifies the 5' and 3' splice sites, at the ends of the intron and the branch point site within the intron.

✏️Cleavage:
-The spliceosome cuts the pre-mRNA at the 5' splice site, releasing the intron as a lariat-shaped structure.
-Formation of the spliceosome: 
-The 5' end of the intron is connected to the branch point site, forming a loop, while the 3' end of the intron is connected to the 5' end of the next exon.

✏️Exon ligation:
-The spliceosome catalyses the joining of the two exons, releasing the intron lariat and forming the mature mRNA.