Q. What’s all this about DNA having a hidden code or second language that may be responsible for triggering diseases? And what is DNA anyway?
A.It sounds a bit like The Da Vinci Code, right? That’s what scientists are reporting; DNA in the mitochondria may have (in effect) a hidden code. I addressed a couple of these findings in my blog toward the end of December.The human genome—and every person’s is slightly different—your complete set of genetic information, the blueprint of how you were built, is encoded within pairs of chromosomes in the cell nucleus. One sperm and one egg each donate 23 pairs of chromosomes resulting in a total of 46 pairs. A chromosome is a single piece of coiled DNA containing many genes. DNA consists of two long, twisted strands that contain complementary genetic information, like a picture and its negative.
Although many don’t realize this, the genetic code uses a 64-letter alphabet. The letters (codons) are organized into words and sentences called genes, a segment of DNA passed down from parents to child that confers a trait to the offspring. Humans have 25,000-30,000 genes, usually in pairs (one from each parent).
Since the genetic code was deciphered in the 1960s, scientists have assumed that it was used exclusively to write information about proteins. Scientists at the University of Washington have reported discovering that about 15% of codons are dual-use codons known as duons.
These duons simultaneously specify both amino acids and transcription factor (TF) sequences. It now appears there may be two separate languages, one written on top of the other, so to speak. This means that many DNA changes that appear to alter protein sequences may actually cause disease by disrupting gene control programs or even both mechanisms simultaneously.
Sometimes things go very well; sometimes they don’t. That’s where mutations come in. A mutation is a change in the spelling of a DNA sequence. Every person’s DNA contains mutations that typically are quite harmless. Some mutations, however, are harmful and may be responsible for triggering abnormal conditions and specific diseases.
In human cells, 99% of all DNA is found in the chromosomes; 1% of DNA is in the mitochondria, the energy factories that produce the energy-rich molecule known as ATP or adenosine triphosphate. Scientists are linking mitochondrial DNA defects with a wide range of age-related diseases including neurodegenerative disorders, some forms of heart disease, diabetes and various cancers.