A3243G
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DNA
DNA stands for Deoxyribose Nucleic Acid.
In humans, DNA is the molecule that encodes genetic information. The
vast majority of the genetic information is stored in the nucleus of the cell.
There is also a tiny bit of DNA in the mitochondria.
DNA is a double-stranded molecule held together by weak hydrogen bonds
between base pairs of nucleotides. The molecule forms a double helix in which
two strands of DNA spiral about one other. The double helix looks something like
an immensely long ladder twisted into a helix, or coil. The two sides of the
"ladder" are formed by a very strong backbone of sugar and phosphate molecules, and
a protruding nucleotide. The
"rungs" consist of weak hydrogen bonds between the nucleotide base on
one side of the ladder to the matching nucleotide on the other side of the
ladder.
In nuclear DNA, the "ladders" are immensely long, and are subdivided into
Chromosomes and Genes.
In mtDNA, the top of the "ladder" joins the bottom of the ladder to form a
circle.
There are four nucleotides in DNA. Each nucleotide contains a base: adenine
(A), guanine (G), cytosine (C), or thymine (T). Due to the shape of each of
these nucleotides bases, 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 genetic code in DNA is in triplets, known as Codons, such as ATG. The base sequence of that
triplet in the partner strand is therefore TAC.
The first proof that DNA was the hereditary material was provided in 1944 by
Oswald Avery, Maclyn McCarty and Colin MacLoed. The double helical structure of
DNA was discovered in 1953 by James D. Watson and Francis H.C. Crick with the
invaluable collaboration of the X-ray crystallographer Rosalind Franklin. Watson
and Crick shared the 1962 Nobel Prize in Physiology or Medicine with Maurice
H.F. Wilkins.
See Also
Codon
mtDNA
RNA
Author: Andy Collinson.
Although I don't have any medical qualifications,
as a sufferer of Diabetes, Deafness and Tinnitus caused by the A3243G mtDNA defect,
I do have a very keen interest in the subject.
Date Page Updated:
25 April 2005
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