WHAT'S THE FABRIC OF YOUR GENES?

Even before the lonely monk Gregor Mendel and his pea pods demonstrated that genes segregate in a discrete manner, scientists have struggled to understand the genetic material.

Fig 1. Incest is best. By playing sick games with smooth and wrinkled peas, Gregor Mendel established the basis of modern genetics. He showed that smoothness was a trait carried by two alleles: big S, the dominant allele that makes peas smooth, and little s, the recessive allele that makes peas wrinkled. Every pea plant carries two alleles for the trait, and only those plants that carry two recessive alleles are wrinkled. But what are these "alleles?" What kind of stuff are they made of?

Over time, it became clear that the gene stuff, whatever it was, had to reside in cell nuclei. As early as 1902 Sutton suggested that it resided specifically in chromosomes, which segregated during the process of cell division. Cell biologists soon ascertained that chromosomes were made mostly of proteins and an acidic material which, naturally enough, they named nucleic acid.