In this video, we're going to talk about RNA splicing and how RNA splicing helps to create mature mRNA molecules. Now, recall that RNA splicing is a eukaryotic process that only occurs in eukaryotes but does not occur in prokaryotes. It's essential to note that even within eukaryotic genes within the DNA of eukaryotes, there are regions called introns and exons. We'll introduce what these introns and exons are very shortly here, but it's essential to note again that these eukaryotic genes have introns and exons. When eukaryotic genes are transcribed, they are transcribed into the premature mRNA, which will contain introns and exons.
RNA splicing is a eukaryotic process critical for removing some regions of the pre-mRNA, specifically the introns. RNA splicing involves reconnecting the remaining regions of the pre-mRNA, which are the exons. Note that introns, which start with 'IN,' are non-coding regions of DNA and RNA, meaning that they do not code for amino acids or proteins. These noncoding regions of DNA or RNA intervene or interrupt the coding regions of DNA or RNA. Therefore, introns do not get translated into protein. The 'IN' prefix in introns can remind you that they are intervening and interrupting. On the other hand, exons, starting with 'EX,' are coding regions of DNA and RNA that get expressed, which means they are translated into protein. We will discuss more about translation later in our course. Originally, DNA and RNA will have introns that need to be removed, and exon regions that need to be reconnected and expressed.
The spliceosome, a large cellular complex of RNA and protein, is responsible for removing the introns and splicing, or reconnecting, the exons. Below we can better understand these introns and exons and RNA splicing. It states here that the spliceosome will remove introns from the pre-mRNA transcript after transcription. At the top, the representation is of the DNA, the eukaryotic DNA, which has a promoter region initiating transcription and a terminator region that ends transcription. Between these, we have the coding region, containing exon and intron regions. The exons are represented by reddish regions, and the introns by bluish regions. When the DNA is transcribed, the premature mRNA is developed, containing both exons and introns. Thus, the introns intervene or interrupt the exons, which ultimately get expressed. Zooming in, the spliceosome formation shows that the blue regions, the introns, are being pinched off and removed, and the red regions, the exons, are reconnected.
This representation of RNA splicing leads to a mature mRNA transcript. Examining these mature mRNA transcripts, they appear processed due to the 5′ cap (guanine cap) and the poly-A tail. All the introns have been removed through RNA splicing, and the exons reconnected. The exons ultimately get expressed, translating into an amino acid sequence to help form a protein. There is also alternative RNA splicing, a process where single genes can be spliced differently to yield multiple products. You can see how the premature mRNA transcript can be spliced in multiple ways, with some exons acting as introns in alternative splicing. Depending on RNA splicing, a single gene can lead to multiple protein products.
This conclusion provides a brief introduction to RNA splicing and its role in creating a mature mRNA ready for translation, occurring only in eukaryotic organisms. As we move forward in our course, we will practice applying these concepts.
See you all in our next video.
