Studying biology for decades has taught Institute Professor Phillip Sharp that human beings are put together like a Rube Goldberg contraption: biological systems have solved problems over the millennia by jerry-rigging what's available.
"You are such a complex system that you can never be optimized," said Professor Sharp at a Family Weekend luncheon in the Stratton Student Center on Friday. "You are not necessarily an efficient machine... just the best available at the moment."
Professor Sharp, who won the 1993 Nobel prize in physiology/medicine, was recognized for his 1977 discovery of a genetic component called an intron. Non-coding sequences of DNA within a gene, introns are cut out of the message by RNA splicing in the nucleus. He found that unlike bacterial genes, human genes have long sections of these "nonsense sequences" separating the essential segments that code for proteins.
He passed through the room a long piece of rope representing the structure of a gene, telling the group that "99.4 percent of this sequence is spliced out and has no function except to separate the segments."
Professor Sharp, who is still working on deducing the chemistry of the gene-splicing process, said this puzzling feature seems to make it possible to allow new combinations for new genes. Introns are thought to play an important role in allowing rapid evolution of proteins. "At one point, it was important to have introns and from then on, we have introns in our genes," he said.
The next big hurdles for biology, Professor Sharp said, are the Human Genome Project, which is expected to sequence every human gene by next year, and a complete molecular understanding of the human brain, which he said is probably another 50 years away. He said that he tells today's undergraduates, "I'm going to teach you what I know about genes, but I believe that someday you will be able to teach me how the brain works."
A version of this article appeared in MIT Tech Talk on October 20, 1999.
