"Rev Dr" Lenny Flank
Posts: 2560
Joined: Feb. 2005
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| Quote (skeptic @ Dec. 25 2006,23:38) | | My question relates to conserved genes and specifically those that are conserved in vastly different species. Is it the commonly held assumption that these genes are just remnants that are not expressed or are they actually active genes? |
There are several genes that are conserved across virtually all life, and others that are conserved across virtually all multicellular life. In nearly every case, these are basic central "housekeeping" genes that perform the most basic and vital cell functions. Since they work well enough to get the job done, there's not much point in changing them. At the cellular biochemical level, all life is pretty much the same -- a banana cell isn't very different from a human cell. They all have to do the same basic biochemical tasks, and since they're all descended from each other, the simplest solution is to keep doing the same thing, over and over and over. (It's the NON-descendents, like virii and the most primitive prokaryotes, who show different biochemistries).
As for multicellular organisms, all the really important stuff happened in the pre-Cambrian (how to make cells stick together into one body, how to form various internal layers, how to determine front from back and up from down). Since then, multicellular life has consisted simply of minor variations on the same theme -- multicellular animals are just tubes with various numbers of things sticking out the sides. At the basic biochemical level, a flatworm and a human simply are not that different from each other.
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