Cold Spring Harbor, NY - The DNA Learning Center is releasing, on July 30, 1999, the second section of its online genetics primer, DNA from the Beginning (http://vector.cshl.edu/dnaftb/). The first section, released in January 1999, covered 14 key concepts of "Classical Genetics" and reviewed experiments and theories of Gregor Mendel, Thomas Hunt Morgan and other 19th and 20th century biologists. The second section covers 10 key concepts of "Molecules of Genetics" and includes:

• DNA and proteins are key molecules of the cell nucleus: featuring Frederic Miescher's discovery of "nuclein," and Phoebus Levene's work on the chemical components that make up DNA.
• One gene makes one protein: featuring the classic Beadle and Tatum experiment with the mold, Neurospora.
• A gene is made of DNA: featuring Fred Griffith and Oswald Avery's work on Pneumococcus, which used the bacterium to show that DNA carries genetic information.
• Bacteria and viruses have DNA, too: featuring Joshua Lederberg's studies of bacterial recombination and the Hershey and Chase experiment confirming that DNA is the molecule of heredity.
• The DNA molecule is shaped like a twisted ladder: featuring the discovery that the structure of DNA is a double helix, by James Watson and Francis Crick.
• A half-DNA ladder is a template for copying the whole: featuring the Meselson-Stahl experiment showing that each DNA strand acts a s a template for the synthesis of new DNA, and Kornberg's identification of DNA polymerase as the enzyme that catalyses DNA synthesis.
• RNA is an intermediate between DNA and protein: featuring the Central Dogma theory, Paul Zamecnik and Mahlon Hoagland's studies of transfer RNA, and Sydney Brenner's work on messenger RNA.
• DNA words are three letters long: featuring Marshall Nirenberg and Philip Leder's experiments on how they cracked the genetic code.
• The RNA message is sometimes edited: featuring Richard Roberts and Philip Sharp's work on RNA splicing.
• RNA was the first genetic molecule: featuring Stanley Miller's creation of organic molecules in the laboratory, and Thomas Cech's discovery that RNA can act like an enzyme, a "ribozyme."

Consistent with the format of the first section of the DNA from the Beginning web site, the key experiments of each concept are explained through computer animations. Each concept also has a Gallery (of still images), Audio/Video (interviews with scientists), Problem (to test comprehension), Bio (biographies of key scientists) and Links (web links).

DNA from the Beginning is designed to provide basic information that anyone would find useful in facing a "personal genetic dilemma." Its target audience is non-scientists with an interest in science, particularly genetics. The material was developed at the level of a bright teenager. With the release of the second section of DNA from the Beginning, two of five planned sections of the primer are now complete.

The next section, "Genetic Organization," will focus on the organization of genetic information within a genome, and will be released in the fall of 1999.

The DNA Learning Center is an educational facility of Cold Spring Harbor Laboratory. Its mission is to provide genetics information to students, teachers and the public. Cold Spring Harbor Laboratory is a private, non-profit basic research and educational institution with programs focusing on cancer, neurobiology, and plant biology. Its other areas of research expertise include molecular and cellular biology, genetics, structural biology, and bioinformatics. In 1998, the Laboratory established the Watson School of Biological Sciences, which offers an innovative Ph.D. program for a small group of exceptional students. Located on the north shore of Long Island, 35 miles from Manhattan, the Laboratory was founded in 1890 as a field station for the study of evolution. Today, the Laboratory is headed by Director Bruce Stillman and President James D. Watson.