| deoxyribonucleic acid: an extremely long macromolecule that is the main component of chromosomes and is the material that transfers genetic characteristics in all life forms, constructed of two nucleotide strands coiled around each other in a ladderlike arrangement with the sidepieces composed of alternating phosphate and deoxyribose units and the rungs composed of the purine and pyrimidine bases adenine, guanine, cytosine, and thymine: the genetic information of DNA is encoded in the sequence of the bases and is transcribed as the strands unwind and replicate. |
DNA  (dē'ěn-ā')   (click for larger image in new window) n. A nucleic acid that carries the genetic information in the cell and is capable of self-replication and synthesis of RNA. DNA consists of two long chains of nucleotides twisted into a double helix and joined by hydrogen bonds between the complementary bases adenine and thymine or cytosine and guanine. The sequence of nucleotides determines individual hereditary characteristics. [d(eoxyribo)n(ucleic) a(cid).] |
The molecule that carries genetic information in all living systems (see genetic code). The DNA molecule is formed in the shape of a double helix from a great number of smaller molecules (see nucleotides). The workings of the DNA molecule provide the most fundamental explanation of the laws of genetics.
DNA acts in three important way. First, when a cell divides, the DNA uncoils, and each strand creates a new partner from the surrounding material — a process called replication. The two cells that result from the cell division have the same DNA as the original (see mitosis). Second, in sexual reproduction, each parent contributes one of the two strands in the DNA of the offspring. Third, inside the cell, the DNA governs the production of proteins and other molecules essential to cell function.
DNA (dē'ěn-ā')
n.
Deoxyribonucleic acid; a nucleic acid that consists of two long chains of nucleotides twisted together into a double helix and joined by hydrogen bonds between complementary bases adenine and thymine or cytosine and guanine; it carries the cell's genetic information and hereditary characteristics via its nucleotides and their sequence and is capable of self-replication and RNA synthesis.
DNA
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