Dictionary

DMD Duchenne muscular dystrophy. See muscular dystrophy, Duchenne.

DNA 1 Deoxyribonucleic acid, one of the two molecules (along with RNA) that encode genetic information. DNA is double-stranded. The two strands are held together by weak hydrogen bonds between base pairs of nucleotides to form a double helix. The double helix looks something like an immensely long ladder twisted into a helix, or coil….

DNA, mitochondrial The DNA of the mitochondrion, a structure situated in the cytoplasm of the cell rather than in the nucleus, where all the other chromosomes are located. Abbreviated mtDNA. mtDNA is inherited from the mother. There are 2 to 10 copies of the mtDNA genome in each mitochondrion. mtDNA is a double-stranded, circular molecule….

DNA, recombinant DNA made up of DNA molecules of different origins, joined together by using recombinant DNA technology. A recombinant DNA molecule is constructed (recombined) from segments from two or more different DNA molecules. Under certain conditions, a recombinant DNA molecule can enter a cell and replicate there.

DNA cloning The use of DNA-manipulation procedures to produce multiple copies of a single gene or segment of DNA. See also DNA, recombinant.

DNA polymerase An enzyme that catalyzes (speeds) the polymerization of DNA. DNA polymerase uses preexisting nucleic acid templates and assembles the DNA from deoxyribonucleotides.

DNA repair The process by which a cell uses a series of special enzymes to repair mutations (changes) in DNA and restore the DNA to its original state. The DNA is constantly mutating and being repaired. This repair process is controlled by special genes. A mutation in a DNA repair gene can cripple the repair…

DNA repair gene A gene that is engaged in DNA repair. When a DNA repair gene is altered, mutations pile up throughout the DNA.

DNA repair pathway The sequence of steps in the repair of DNA. Each step is governed by an enzyme.

DNA replication A complex process whereby the “parent” strands of DNA in the double helix are separated, and each one is copied to produce a new (daughter) strand. This process is said to be “semiconservative” because one strand from each parent is conserved and remains intact after replication has taken place.

DNA sequence The precise ordering of the bases (A, T, G, C) from which DNA is composed. Base pairs form naturally only between A and T and between G and C, so the base sequence of each single strand of DNA can be simply deduced from that of its partner strand. The DNA nucleotide code…

DNR Do not resuscitate.