Science Friday: Nobel Prizes for Medicine and Chemistry

Here's some science for you—I'm taking advantage of the public wireless outside in downtown Carrboro and it's quite unpleasantly chilly out here. Fall sure did roll in since last week, and I'm not looking forward to lows in the 30s over the next few days. But more relevant to this post is that a bunch of Nobel Prizes were awarded over the last couple weeks. The Peace Prize got plenty of attention already, and since the other prizes hardly got any I won't give it any more. This week's post is devoted to the Medicine and Chemistry prizes.

This year's Medicine prize was given to a few researchers for their work on the DNA at the ends of our chromosomes called telomeres. Going back to high school bio, each person's DNA is divided between 23 pairs of DNA structures called chromosomes. These are essentially really long strands of DNA that are coiled up tightly, so that a foot-long segment of DNA can be contained in a microscopic chromosome. The telomeres at the end of chromosomes are kind of funny though.

So, when a cell divides into two, as they frequently do, the DNA has to be copied so that each resulting cell has a complete set of it. So, some proteins called enzymes (specifically, helicase and DNA polymerase) attach themselves to the chromosomes and move down the strand, making a copy of the DNA as they go. So, your two new cells end up with all the DNA they need. Well, almost. The enzymes attach close to the end of the DNA strand, but can't quite attach to the very end—meaning that each time cells divide and DNA is copied, a bit of it is lost. If that kept happening, then the genes near the end of the DNA strand (suppose it's a zombie virus resistance gene) eventually would be lost, and you'd be a zombie moaning for brains and your lost telomeres. That would be bad.

Fortunately, that doesn't happen. Scientists had suspected for a long time that telomeres provide some protective function to chromosomes, and in the 1980s, Elizabeth Blackburn, Jack Szostak, and Carol Greide found out how. Blackburn first discovered that telomeres were made of short DNA segments repeated over and over again. She and Szostak then cut some telomeres out of pond-dwelling protozoan cells, and attached them to chromosomes in yeast cells. Yeast and pond-dwelling protozoans aren't related—not even close—but the telomeres protected the yeast chromosomes just fine. Telomeres therefore had to have developed pretty early on in the history of life to be so transferable between unrelated organisms. Blackburn and Greide then discovered how the telomeres worked: after cell division, a previously undiscovered enzyme, telomerase, takes an RNA strand (RNA is another long molecule that can store genetic information) complementary to the lost telomere segment and uses it to recreate the telomere strand.

Since then, several diseases have been found to be associated with defects in this telomere-writing process, and therapies are currently in development. Telomerase-related therapies have been proposed to slow aging, but have so far been foiled by their tendency to encourage cancer growth (which is heavily dependent on low costs to cell division.) This current work would have been impossible without these scientists' breakthroughs.

The Chemistry prize is also related to cell biology. So, DNA is where your genetic information is stored. The information it stores is mainly about proteins—which ones to make, and when. To make the proteins (which carry out a lot of the cell's needs), the information is copied onto a strand of RNA, which is then fed through organelles called ribosomes (cell components like ribosomes, the nucleus, and the cell membrane are called organelles, and are analogous to the body's organs.) Ribosomes take the genetic information on the RNA and use it to assemble the proteins. If you know much about computers, it's similar to taking a file out of long term storage on the hard drive (DNA) into short term storage in RAM (RNA) and sending it to the printer (ribosome), where it's converted into a useful printout (protein).

The problem with studying ribosomes is that the microscopes used to study things that small are good at studying orderly, crystalline substances. Ribosomes are asymmetrical, irregular blobs of tangled up RNA and proteins—not the easiest thing to work with. Scientists thought it was probably impossible to put ribosomes in such a form that microscopes would work on them—until Ada Yonath found a way in 1980. She and her collaborators Venki Ramakrishnan and Thomas Steitz spent the next two decades improving her crystal preparation and imaging techniques. In 2000, they published a set of high resolution images showing the structure of the ribosome's two subunits.

So, that's awesome—they figured out how a really important organelle works. It gets better though: half of all known antibiotics specifically target bacterial ribosomes. Ramakrishnan, Steitz, and Yonath, along with many other scientists, have begun studying how those antibiotics attack harmful bacteria. Their work investigating this major vulnerability of pathogens has been kind of like R2D2 showing the Death Star blueprints to rebel pilots, if you'll permit the analogy, and will prove essential to the development of new medicines.

In other science news:

A recently-discovered exoplanet closely orbiting the star COROT-7 appears to be hot enough to vaporize its surface rocks. Chemical models suggest that the rock vapor later condenses and precipitates, making rocks and lava fall from the sky like rain.

Fossils suspected to be a “missing link” in the evolution of pterosaurs have been discovered. Pterosaurs, flying reptiles that lived during the Mesozoic, were not dinosaurs, and included, among others, pterodactyls and quetzalcoatlus.

Volcanologists have found that under certain conditions, magma in shallow volcanic magma chambers can rise to the surface very rapidly—up to a meter per second. This would mean that sometimes, the volcano's impending eruption would not be detectable soon enough to evacuate the area properly.

Teams from several universities around the country built solar-powered homes on the National Mall in DC last week. The “Solar Decathlon” featured many innovative designs, some of which have been in preparation for two years.

NASA attacked the moon on Friday, crashing a rocket and satellite into it on Friday morning. It didn't make a pretty explosion, and a bunch of astronomy enthusiasts were disappointed, but the scientists got the data they needed. The mission's objective was to kick up some lunar dust and rock to see what was in it, and particularly to see if it contained water.

Saturn has a really huge ring, previously undiscovered. Mmm, pretty pictures...

The Army Corps of Engineers knew for about a century before Katrina that the way they built the levees would cause something very bad to happen. You have to put up with Chris Matthews talking over his guest, but it's worth it.

Next week: Physics and Econ!