Question

Q2: The Human Genome Project (HGP) was one of the great feats of exploration in history. Beginning on October 1, 1990 and completed in April 2003, the HGP gave us the ability, for the first time, to read nature's complete genetic blueprint for building a human being. About 20,000-25,000 protein coding genes were reported for humans yet the estimated number of proteins in human cells can be up to 100,000. Give an explanation for this 3-4 sentences.

Answer 1

The human genome is made of both protein coding regions or exons and non-coding regions known as introns. During transcription, the introns are spliced out and the remaining exons are joined together to form the mature mRNA. This joining of the exons may be done in a different order or by skipping certain exons resulting in various forms of mRNA from the same coding gene by a process known as alternative splicing. The mature mRNA generated is further translated to produce proteins. This way the mRNA's produced from the same gene may code for different proteins due to the difference in sequence of amino acids that they specify, thus contributing to protein diversity. Other ways of producing different proteins from one gene include alternative translation where post-translational gene regulation results in different isoforms of proteins produced from the same mRNA.