How is RNA spliced during transcription?

RNA is spliced during transcription by removing introns and joining exons together to form a mature mRNA molecule.

RNA splicing is a crucial process that occurs during the transcription of a gene. It involves the removal of non-coding sequences, known as introns, and the joining together of coding sequences, known as exons. This process is carried out by a complex of proteins and RNA molecules known as the spliceosome.

The process begins when the RNA polymerase II enzyme transcribes a gene into a pre-mRNA molecule. This molecule contains both exons, which are sequences that will be translated into protein, and introns, which are sequences that will not be translated. The presence of introns and exons in the pre-mRNA molecule is a characteristic feature of eukaryotic genes.

The spliceosome recognises specific sequences at the ends of each intron. These sequences signal where the intron begins and ends. The spliceosome then cuts the pre-mRNA at these points and removes the intron. The remaining exons are then joined together to form a mature mRNA molecule. This molecule is then ready to be translated into a protein.

The process of RNA splicing is highly regulated and precise. Errors in splicing can lead to the production of incorrect proteins, which can have serious consequences for the cell. For example, many genetic diseases are caused by mutations that affect the splicing process.

RNA splicing also allows for a single gene to produce multiple different proteins. This is because different combinations of exons can be joined together during the splicing process, resulting in different mRNA molecules. This process, known as alternative splicing, increases the diversity of proteins that a cell can produce.

In summary, RNA splicing is a vital process that occurs during the transcription of a gene. It involves the removal of introns and the joining together of exons to form a mature mRNA molecule. This process is carried out by the spliceosome and is highly regulated to ensure the correct proteins are produced.