Sublime

Avery searched for radioactivity and found it only within the bacteria, not the virus shells. Hershey and Chase then reversed the experiment, spiking the protein in the viruses with radioactive tracers. Once the viruses had infected E. coli, only the empty shells were radioactive. A decade after Avery’s experiment,

Genes, which carry the codes to build proteins, are physically located in a double-stranded, helical molecule called deoxyribonucleic acid (DNA), which is further packaged in human cells into skein-like structures called chromosomes. As far as we know, DNA is present inside every living cell (unless it has been ejected from the cell).

In nineteen tubes nothing happened. The twentieth tube was filled with the amino acid phenylalanine, and only in that tube did new proteins form. Nirenberg and Matthaei had discovered the first entry in life’s dictionary: UUU equals phenylalanine. Over the

“Deoxyribonucleic acid,” I say. “It’s a molecular blueprint for all living things and it’s composed of nucleotides.” He squints at me, unsure of what to think. “Which are?” “Molecules.” I say. “And yeah, I know that a molecule is a bunch of atoms stuck together. DNA is a four-letter code. A. T. G. and C. Adenine, thymine, guanine, and cy…cy…” “Cyto

Meselson and Stahl then ran a second version of the experiment. They moved some of the heavy-nitrogen E. coli into a flask where they could feed on normal nitrogen, with only fourteen neutrons apiece. The bacteria had just enough time to divide once before Meselson and Stahl tossed their DNA in the centrifuge. If Watson and Crick were right about h

To see how the mold’s genes control those enzymes, Beadle and Tatum bombarded it with X-rays.