The parasympathetic nervous system activates the relaxation, or rest-and-digest, response. Roughly the opposite of the fight-or-flight response of the sympathetic nervous system, the relaxation response involves restoration of energy reserves and other peace time functions, such as repair and reproduction.
On this day in 1953, Cambridge University scientists James D. Watson and Frances H.C. Crick announce that they have determined the double-helix structure of DNA, the molecule containing human genes.hough DNAâshort for deoxyribonucleic acidâwas discovered in 1869, its crucial role in determining genetic inheritance wasnât demonstrated until 1943. In the early 1950s, Watson and Crick were only two of many scientists working on figuring out the structure of DNA.
Watson and Crick describe structure of DNA1953. Photo: Model of DNA molecule. In the late nineteenth century, a German biochemist found the nucleic acids, long-chain polymers of nucleotides, were made up of sugar, phosphoric acid, and several nitrogen-containing bases.Later it was found that the sugar in nucleic acid can be ribose or deoxyribose, giving two forms: RNA and DNA.atson and Crick describe structure of DNA1953. Photo: Model of DNA molecule. In the late nineteenth century, a German biochemist found the nucleic acids, long-chain polymers of nucleotides, were made up of sugar, phosphoric acid, and several nitrogen-containing bases.