How Are Your Genes Doing

I'd like to recommend an article that appeared in this past Tuesday's Science Times. Carl Zimmer has written a four page review of new advances in genetics research, Now - The Rest of the Genome, in which he discusses the flexibility which which genes express themselves depending upon circumstances within a given cell or cells. Particular genes apparently are not programmed to produce a specific protein. Here is an excerpt in which he introduces the subject:

It turns out, for example, that several different proteins may be produced from a single stretch of DNA. Most of the molecules produced from DNA may not even be proteins, but another chemical known as RNA. The familiar double helix of DNA no longer has a monopoly on heredity. Other molecules clinging to DNA can produce striking differences between two organisms with the same genes. And those molecules can be inherited along with DNA.

The implications of this are obviously enormous, not only for basic science but for the treatment of disease and so on.Who is not fascinated by the scientific advances, as well as the more immediate health-related promise , in the filed of genetics. Certainly I am, even though I am somewhat squeamish about the implications of cloning.

That now people with dangerous genetically transmitted diseases can risk pregnancy freely because they have the opportunity to find out whether or not dangerous genetic mutations have to the foetus very quickly after conception, is a wonderful liberation for would be parents with a  compromised genetic heredity. Still I have some qualms even when it comes to the application genetic engineering to agriculture, not to speak of far-out proposals that genetically engineered designer babies are in our human future. There is always the possibility of unintended consequences to consider.

What has troubled me most in popular discussions of genetics, is the notion that there is a simple connection between behavior and genetic inheritance, as in the case of such hot-button subjects as the presumed on-on-one relationship between sexual preference say and genetics. To my mind we are all bisexual to some degree. In any event  I fail to see any justification for bigotry against people who freely choose their partners or conversely any particular reason to "justify" sexual preference by assuming it is gentically preprogrammed.  I have also come across books and articles suggesting that people have "evil genes." Now that really smacks of the view of genetics that was popular in eugenicists who supported Hitler's view of the master race.

Zimmer does not take up any of these issues, so even if you don't agree with my philosophical ramble, I urge you to take a look at his article.



Some very interesting new stuff going on, I don't remember the transient heritability of epigenetic changes, for one thing.  That's where non-DNA changes in the genome can pass through a few generations without changing the coding DNA.

But this piece reminded me of one of the areas I find coolest in the molecular sciences, the comparison of genomes from closely related species to see what makes us different, for example, from chimps.

Between humans and chimps, a number of sequences that we still find useful have 'degraded' in our chimp cousins,


But the line between the useless baggage and the useful DNA is hard to draw. Mutations can make it impossible for a cell to make a protein from a gene. Scientists refer to such a disabled piece of DNA as a pseudogene. Dr. Gerstein and his colleagues estimate that there are 10,000 to 20,000 pseudogenes in the human genome.

and a bunch of those have been found involved in our ability to speak.  There are others, I seem to recall, that I think the chimps still use but we don't which play roles in making and responding to pheromones, the chemical signals that are sensed by 'smell'.  In humans, those sequences are probably seen as pseudogenes.

Thanks for the pointer!


"I hope we shall crush in its birth the aristocracy of our moneyed corporations which dare already to challenge our government in a trial of strength, and bid defiance to the laws of our country." - Thomas Jefferson

I remember when most of genetic material was labelled as "junk." Now they are finding controlling meta genes in the so-called junk which also determine when genes are turned on or off (ie expressed or not.)