Home   |  Issues  |  The Daily Star Home | Thursday, August 21, 2003

 

 

 

 

G E N E

By Solitary Sniper

The molecules that program our biological potential, deoxyribonucleic acid, or DNA, is beginning to yield its secrets. As scientists map our genetic universe, we look forward to the promise of curing diseases and solving mysteries of forensics and evolution. But advances in knowledge also bring thorny ethical questions. For example, sperm-sorting technology improves parents' chances of choosing a child's sex. Are we really ready for the gene age?

More than fifty years ago, Watson and Crick had uncovered what was the shape of a now familiar molecule called deoxyribonucleic acid. A Swiss scientist had isolated the chemical from the white blood cells way back in 1869, but neither he nor anyone else for over half a century had any idea of its importance to life. It wasn't until a few years before Watson and Crick began work that an American bacteriologist named Oswald Avery demonstrated that DNA was the stuff of genes discrete, inheritable packets of information aligned along the chromosomes inside the cell's nucleus. Watson and Crick puzzled out that the DNA is shaped like a twisted staircase the famous double helix. The two strands of the helix consist of immensely long strings of sub-units called nucleotides. These, in turn, contain sub-subunits called bases that are referred to by the letters A, C, T and G. Now let us think of those four bases as letters in a four-letter alphabet. Just as we arrange the letters of our alphabet into meaningful words, the bases that make up our genes are arranged into three letter "words" comprehensible to the machinery of the cell. Each gene is a sentence composed of a precise order of these words, telling the cell to manufacture a particular type of protein. That simple formula one gene makes one protein is part of the central dogma of molecular biology. Like any dogma, it skips over a great deal of detail. In order to make a protein, a gene actually needs help from all kinds of other proteins, such as hormones and enzymes. It needs to know when to turn itself on and when to turn off. The genes of higher organisms are especially complex, their chemical messages riddled with meaningless strings of letters that have to be spliced out before the genes can do their work. Byzantine patterns of repeated words and lengthy sprawls of seemingly nonsensical sequences mask essential instructions not yet understood. None of this was known, of course, back when Watson and Crick were celebrating their discovery at the local pub, where bartenders still serve what they claim was Watson and Crick's usual drink there.

All the information required to make a human being is written into our DNA. The data is roughly a gigabyte in size. The entire genome of a typical human being will easily fit into the hard disk of a desktop PC. There are roughly three billion letters in the human genome. It if were a book and one could read ten letters per second, it would take 11 years to recite the whole text. Even if we did have 11 years to spare, a simple recitation of the code would give no hint of the way it makes human life. Instead of thinking of the genome as a book, we can imagine it to be a piano keyboard. If we press a key, we hear a single note. That note corresponds to the protein that the gene specifies. If we press the key again, we hear the same old sound, over and over again, each time the key is hit. But if we have lots of keys, we can make music. Similarly, our various cell types play upon the immense keyboard of the genome. Just as a pianist doesn't play all the keys in every piece, only some of the genes get played in the cells of each organ.

But now think what will happen to a piano concerto if an important key sticks or sounds wrong when struck. Such a flaw will ruin every passage where that key is played. In some cases it will destroy the music entirely. In the United States one child out of 3900 is born with cystic fibrosis, the most common deadly hereditary disease among Caucasians. The mucus in the lungs is abnormally thick, leaving the child vulnerable to repeated infections that erode the lungs' tissues and eventually the ability to breathe. Half of all sufferers die before their 31st birthday.

Ten years ago researchers in Toronto and at the University of Michigan traced the cause of the disease to a defective gene on chromosome 7. Such single-gene defects account for 3000 to 4000 other inherited diseases. But the research behind which genes affect people in what way is not really getting a warm welcome from the masses, since people are not really sure if they are ready to learn in advance about what sorts of diseases they are predisposed to catch later in life. Knowing that they are pre-disposed to cancer is not really something people would look forward to knowing.

With all the emphasis on genes that cause disease, it is easy to forget that the genome is actually the recipe for life, not death. We know genes play a role in influencing behavior and personality; studies showing that identical twins raised apart share an uncanny number of behavioral traits backs that up. But so far attempts to tag a particular behavior to a particular gene have been problematic because such complex behaviors necessarily involve the co-operation of many genes. On the genomic piano, behaviors and personality traits are not single notes but intricate compositions.

Today scientists all over the world are using mitochondrial DNA to re-create the migrations of other ancient people across Africa, the Americas, and everywhere in between. It is important to keep in mind, however, that the exquisite diversity in our mitochondrial code that allows us to trace these events is a classic exception that proves the rule. In most of the rest of our genes every human being alive is exactly the same. Moreover, most of the variations in the remaining one-tenth of a percent don't bunch up into geographic regions or racial groups but instead are spread around the globe. Put another way, the snips and snippets of codes that taken together make one person unique are scattered about in other unique genomes all over the world, binding all of us in a splendid tangle of interrelationship. That tangle doesn't begin at our evolutionary branch but spreads up from far below. All the anatomical differences between human beings and chimpanzees, and even the hallowed uniqueness of human cognition, may in fact arise from a few changes regulating fetal developments. Nine-tenths of our genes are identical to those of a mouse. More than a third of the genes of the nematode worm are shared with the exalted homo sapiens. Genomically speaking, even bacteria are our cousins in code. The last and most powerful secret revealed by our genes, in fact, is the indisputable unity of everything alive.

 

 

Insane Clown Posse Named Worst Rock Band

LOS ANGELES (Reuters) - Insane Clown Posse, the Detroit rap duo beloved by teenage boys for their creepy face make-up and X-rated lyrics, have been named the worst band ever by Blender magazine

The music publication's September issue said Insane Clown Posse "sound even stupider than they look," and derided them for rapping about "40-ouncers and venereal disease."

Officials at the band's Psychopathic Records label were less than enthusiastic about the rating.

No. 2 on the list was 1970s supergroup Emerson, Lake & Palmer, followed by once-hirsute balladeer Michael Bolton, mellow jazz saxophonist Kenny G. and the Jefferson Airplane pop spinoff Starship.


 
 

home | Issues | The Daily Star Home

2003 The Daily Star