Friday, November 14, 2008

Updated refresher course on genes

There's an article in the NYT by Carl Zimmer called "Now: The Rest of the Genome" that discusses some of the new findings about how genes work:
Here are some of the more interesting nuggets:
  • "the average protein-coding region produces 5.7 different transcripts"
  • "cells often toss exons into transcripts from other genes. Those exons may come from distant locations, even from different chromosomes."
  • "When an embryo begins to develop, the epigenetic marks that have accumulated on both parents’ DNA are stripped away. The cells add a fresh set of epigenetic marks in the same pattern that its parents had when they were embryos."
  • "As an embryo matures, epigenetic marks in different cells are altered, and as a result they develop into different tissues. Once the final pattern of epigenetic marks is laid down, it clings stubbornly to cells. When cells divide, their descendants carry the same set of marks."
  • "Although only 1.2 percent of the human genome encodes proteins, the Encode scientists estimate that a staggering 93 percent of the genome produces RNA transcripts."
  • "Dr. Prohaska argues that a gene should be the smallest unit underlying inherited traits. It may include not just a collection of exons, but the epigenetic marks on them that are inherited as well."

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