Tuesday, November 11, 2008

Worn-out Gene

The "one gene, one protein" biological model has lost relevance as the genome and heredity are better understood. As Carl Zimmer writes, the gene "is in an identity crisis". In a great review article, Zimmer outlines how conceptions of genes have changed over time.

The first look at the human genome in 2000 documented about 1% of the genome as DNA making proteins, the other 99% was a bit mysterious. Scientists, including the ENCODE project, have been examining the entire genome, rendering a more complicated picture. One stretch of DNA might code for many different proteins and one protein can be derived from several remote strands of DNA. In addition, other molecules (methyl groups prominent) that are attached to DNA are heritable and modify traits. Together these molecules make up an epigenome, an area of hot research (click on the image). Zimmer further discusses reconsidered roles for RNA and the incorporation of viral DNA into our genome.

All of this demonstrates that we are very early in understanding the genome. Further study promises incredible insights into how we and disease work.

(image credit, "Mapping the Epigenome", Jonathan Corum and Martin Krzywinski, nytimes.com)