Nucleic acid hybridization natural positions within a chromosome). In 1969, the two scientists published a paper demonstrating that radioactive copies of a ribosomal DNA sequence could be used to detect complementary DNA sequences in the nucleus of a frog egg. Since those original observations, many refinements have increased the versatility and sensitivity of the procedure to the extent that in situ hybridization is now considered an essential tool in cytogenetics. Nucleic acid hybridization In molecular biology, hybridization (or hybridisation) is a phenomenon in which single-stranded deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) molecules anneal to complementary DNA or RNA. Though a double-stranded DNA
Prephenic acid Prephenic acid Prephenic acid, commonly also known by its anionic form prephenate, is an intermediate in the biosynthesis of the aromatic amino acids phenylalanine and tyrosine, as well as of a large number of secondary metabolites of the shikimate pathway. It is biosynthesized by a [3,3]-sigmatropic Claisen rearrangement of chorismate. Prephenic acid is an example of achiral (optically inactive) molecule which has two pseudoasymmetric atoms ("i.e." stereogenic but not chirotopic centers), the C1 and the C4 cyclohexadiene ring atoms. It has been shown that of the two possible diastereoisomers, the natural prephenic acid is one that has both substituents at