Microcosm: E. coli and the New Science of Life

Some operons carry several switches, all of which must be thrown for them to make proteins.

Tatum pelted colonies of E. coli with enough X-rays to kill 9,999 of every 10,000 bacteria. Among the few survivors he discovered mutants that could grow only if he supplied them with a particular amino acid. Helped along, the mutants could even reproduce, and their offspring were just as crippled. Tatum had gotten the same results as he had with b

Genes do not work in isolation. They work in circuits. Over the next few weeks, Jacob tried to

glucose. Adams discovered that some of his E. coli were becoming more efficient at feeding on acetate than their ancestors were. The acetate feeders grow slowly, but they aren’t driven to extinction because they are taking advantage of a food that the faster-growing bacteria aren’t eating.

It will keep swimming in longer runs as long as it senses that the concentration of serine is rising. If its tumbles send it away from the source of serine, its swims become shorter.

E. coli’s bacteriophages were not all alike. Some could infect certain E. coli strains but not others. By triggering mutations in the viruses, the scientists could cause the viruses to infect new strains. The ability to infect E. coli passed down from virus to virus.

To survive, E. coli work together. The bacteria communicate and cooperate. Billions of them join together to build microbial cities. They wage wars together against their enemies.

It is only through the switching on and off of genes that our cells can behave differently from one another,

One of these viruses, known as P1, carries a gene that makes a protein called a restriction enzyme. Restriction enzymes are able to grab DNA at specific sites and slice it apart.