Question

DNA sequencing of the human genome suggests that humans have --25,000 genes. However, the proteome (the entire set of proteins expressed by an organism) of humans is considerably larger. Explain briefly how this is possible. 

Additional Information. Below is a codon table, which you may consult if you need to. 

Answer 1

Human genome is smaller than protein in number, it is due to the process of alternative splicing.

Splicing is one of the process of post transcriptional modification. It involves removal of unwanted portion or non-functional parts such as introns from the RNA.

Alternative splicing is one of the method of splicing as the name implies RNA arranged in alternative order. For example if the RNA has five parts it can be arranged in more ways such as 12345, 45213, 24531 or 345, 421, 4321 etc., likewise more number of proteins can be formed from single gene.though there is so much of introns (non-functional parts) present in the genome, more proteome is present by alternative splicing.

Alternative splicing parts number are nearer to number of proteins present. For example Approximately 90000 proteins are there, then 70000 alternative splicing variants are present in humans.