A litte art and a lot of science

Via Boingboing: Here is cool a sculpture by Mara G. Haseltine that was just unveiled at Cold Spring Harbour. It is meant to represent a series of ribosomes moving down an mRNA molecule, translating it into proteins.


Molecular biology 101
Proteins are the stuff of life. As enzymes, they catalyze almost every essential reaction that takes place in the human body. While they play vital structural roles in skin, bones and connective tissue, they can also be dynamic; acting as motors in muscle tissue and pumps in nerve cells. Proteins are the messengers that coordinate the development of an organism and they also act as regulators in the day-to-day maintenance of living things.

But how are these proteins made?

Well, let's start at the start - with genes. Physically, a gene is a length of DNA. Stored in that length of DNA is a set of instructions - instructions on how to make a protein. One gene codes for one protein. The code is very simple, but it is over four billion years old and shared by every living thing on earth, so it must have something going for it. It does, and its simplicity is just one of it's many strengths. The DNA language has four letters, called bases - A, C, G, and T - but it's read in triplets, or groups of three letters. This gives it 64 possible "words". The human body only uses twenty of these words, because it uses only twenty amino acids - the building blocks of proteins - to make everything we are made of. These amino acids are strung together, with peptide bonds, to form polypeptides, or proteins.

The ribosome
Now, to get from a gene to a protein, the triplet code of DNA has to be translated into the twenty-letter amino acid code, and that's where the ribosome comes in. The ribosome is your one-stop-shop for protein synthesis - it's able to read the triplet code of DNA (in the form of messenger RNA, or mRNA), and then string together the corresponding sequence of amino acids to form a protein. It does this, I might add, with a speed, accuracy and efficiency that human chemists will almost certainly not match this millennium, if ever. They are the world's smallest and oldest factories.

Molecular clocks
Since proteins are essential for life (as we know it) it is safe to assume that ribosomes have been around, in some form, just as long. This observation, coupled with the knowledge that over time there is a constant mutation rate in DNA, gave rise to the use of ribosomal DNA (rDNA) sequences as molecular clocks. By analyzing the sequences of rDNA in different organisms, scientists are able to gauge how closely related they are, or more accurately, how long ago the two organisms diverged from one another. By combining these comparisons and collating all this information we are able to construct trees of relatedness or phylogeny. Previously, phylogenic trees were constructed based on morphology, but this genetic method is far more accurate. One of the most profound discoveries to have come out of ribosomal DNA sequence analysis is the discovery of the Archaea, the third domain of life. But that's another story, and besides, it's time for bed now.

- Mr. Ed