Posted on 06/25/2005 10:31:32 PM PDT by neverdem
DNA usually grabs the headlines for its starring role as the archive of genetic information.
But many of the really difficult operations that a cell performs are carried out by RNA, DNA's close chemical cousin.
So deeply has RNA been overshadowed that two of its major roles in the cell have come to light only in the last few years. One, a way of fine-tuning the activity of genes, has been the subject of a flurry of recent reports documenting RNA's part in central operations like stem cells, cell differentiation, insulin production and cancer.
In its fine-tuning role, RNA is known as micro-RNA. It ratchets down the production of certain proteins in cells by binding to target sites on messenger RNA, the envoy from the genes that directs protein production. The precise dose of a protein can be very important: Down syndrome is caused by an extra chromosome and the resulting excess production of proteins whose genes exist in three copies instead of the usual two.
Though it may be inefficient for a cell to generate messenger RNA from a gene and then hobble production of the protein it specifies, micro-RNA seems to provide a sophisticated way of adjusting production levels, particularly of proteins that are needed at one stage of life but must be absent in others.
A particularly important role for micro-RNA may be choking off the production of proteins that maintain cells in an undifferentiated stemlike state, thus forcing the cells to mature into their destined adult forms. In an article in Nature this month, Todd Golub of the Broad Institute in Cambridge, Mass., reports that many kinds of cancer tissue have less micro-RNA than normal cells, suggesting that the tumor cells had backtracked on the normal maturation process and regained the growth potential of stem cells.
(Excerpt) Read more at nytimes.com ...
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A biochemistry article written in the style of a celebrity/political gossip column.
I called messenger RNA's "Mirnas", while I called transfer RNA's, "Trinas". What shall I call micro-RNA's? Ps, this must be new info, I don't remember it from college microbiology.
It's for a general audience for those who still have an interest in science. You can't find graphics like you find in the Times. If you can, I would appreciate it if you show me.
Thanks for posting this!
Yes, it's new. You can find the titles and abstracts, probably, in the link in comment# 1.
Thanx. If I weren't tired (I have to work later on today), I would check out the linx.
They provided an abstract for every article that I checked. You probably have to subscribe for whole articles.
This subject is fascinating, and for me, I wonder about what is the simplest chemical compositions/reactions that would allow duplication.
We have to give a pass to some of the amino acids, they have detected them in fossilized dino bones, some are unbelievably stable.
I am inclined to think Yellowstone and TAQ (Thermus Aquaticus) is the answer. PCR.
Very interesting! Thank you.
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