DNA is a polymer of deoxyribonucleotides. DNA (deoxyribonucleic acid) a complex NUCLEIC ACID molecule found in the chromosomes of almost all organisms, which acts as the primary genetical material, controlling the structure of proteins and hence influencing all enzyme-driven reactions. Periodicity of DNA is defined as the number of base pairs per turn of the double helix.įig. Polypeptide formation occurs indirectly by way of MESSENGER RNA and TRANSFER RNA. Each CODON specifies a particular amino acid to be selected, and the sequence of these, in the polypeptides formed, determines the nature of the protein (usually an ENZYME) synthesized. The sequence of bases along the molecule, taken in groups of three (codons), is the genetic code. This arrangement allows automatic replication of the molecule. The molecules of adenine and guanine are larger than thymine and cytosine and so, to keep the rungs of equal length, adenine links only with thymine and guanine only with cytosine. Between the two helices, lying like rungs in a ladder, are a succession of linked pairs of the four bases adenine, thymine, guanine and cytosine. The molecule has a double helix skeleton of alternating sugars (deoxyribose) and phosphates. ![]() The very long molecule that winds up to form a CHROMOSOME and that contains the complete code for the automatic construction of the body. Medical Dictionary for the Health Professions and Nursing © Farlex 2012 DNA Abbrev.
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