| environ. |
DNA The principal material of inheritance. It is found in chromosomes and consists of molecules that are long unbranched chains made up of many nucleotides. Each nucleotide is a combination of phosphoric acid, the monosaccharide deoxyribose and one of four nitrogenous bases: thymine, cytosine, adenine or guanine. The number of possible arrangements of nucleotides along the DNA chain is immense. Usually two DNA strands are linked together in parallel by specific base-pairing and are helically coiled. Replication of DNA molecules is accomplished by separation of the two strands, followed by the building up of matching strands by means of base-pairing, using the two halves as templates. By a mechanism involving RNA, the structure of DNA is translated into the structure of proteins during their synthesis from amino acids (遗传的基础物质。存在于染色体，由不分支的长链核甘酸分子所组成。 每个核甘酸由磷酸、脱氧核糖和四个含氮碱基(腺嘌呤、鸟粪嘌呤、胞嘧啶、胸腺嘧啶)中之一所组成。 DNA链上核甘酸可能的排列顺序是无限多。 通常两条脱氧核醣核酸链通过碱基配对平行排列形成双螺旋结构。 DNA分子的复制需要将两DNA链分离，然后两链各自作为范本，以碱基配对进行复制。 在胺基酸的合成中，经由含有核醣核酸的机制，DNA的结构被转译进入蛋白质的结构中。) |
