What is splicing and alternative splicing?
When a gene is switched on, the DNA sequence is copied into a molecule of messenger RNA (mRNA) which is then translated in a protein. The many thousands of genes in an organism generate proteins with different functions which either carry out chemical reactions or are building blocks for cells and organs. The majority of protein-coding genes in plants and animals contain introns which must be removed from precursor mRNAs to produce mRNAs. This process is called splicing and involves conserved splicing signals in the intron and the assembly of a large complex of around 200 proteins. It has been estimated that at any moment in time, each cell in the human body is engaged in splicing 20,000 introns. Figure: Alternative splicing of pre-mRNA gives rise to different mRNAs and proteins Alternative splicing is where more than one mRNA is produced from the same precursor messenger RNA (pre-mRNA), giving rise to functionally different proteins. In humans there are approximately 30,000 genes and
