What is junk DNA, and what is it worth?
Wojciech Makalowski, a Pennsylvania State University biology professor and researcher in computational evolutionary genomics, answers this query. Our genetic blueprint consists of 3.42 billion nucleotides packaged in 23 pairs of linear chromosomes. Most mammalian genomes are of comparable size—the mouse script is 3.45 billion nucleotides, the rat’s is 2.90 billion, the cow’s is 3.65 billion—and code for a similar number of genes: about 35,000. Of course, extremes exist: the bent-winged bat (Miniopterus schreibersi) has a relatively small 1.69-billion-nucleotide genome; the red viscacha rat (Tympanoctomys barrerae) has a genome that is 8.21 billion nucleotides long. Among vertebrates, the highest variability in genome size exists in fish: the green puffer fish (Chelonodon fluviatilis) genome contains only 0.34 billion nucleotides, while the marbled lungfish (Protopterus aethiopicus) genome is gigantic, with almost 130 billion. Interestingly, all animals have a large excess of DNA that d
