Question

Before the Human Genome Project was finalized, it was assumed that there should have been approximately 100,000 genes coding for proteins. However, it is found out that many human genes are capable of making more than one protein, allowing human cells to make at least 100,000 proteins from only about 20,000 genes. What is the main modification responsible for this outcome? Explain briefly the mechanism of this modification (process).

Answer 1

The main modification responsible for this outcome is called alternative splicing. Most human genes contain multiple segments called exons, separated by intervening non-coding sequences called introns. One of the ways that cells produce multiple protein isoforms from individual genes is by alternative splicing. Different mRNA molecules are produced from the same primary transcript depending on which RNA segments are treated as exons and introns. If the cell stitches the exons together in one way, it makes one protein. If it stitches the exons together in another way, it makes a different protein. As a result, a single gene can actually produce many different proteins