- The molecule holding the design information used to construct components (proteins and enzymes) of biological (living) systems.
Contrary to widely taught and popularly held belief, DNA is not a self-replicating molecule.
DNA stores information as a code made up of four chemical bases:
These always pair up into only two possible pairs of bases:
: Adenine with Thymine, and
: Cytosine with Guanine
Each base (A, T, C, or G) of a DNA molecule is combined with a phosphate group and a sugar molecule. This configuration of base, phosphate, and sugar molecule is called a nucleotide
. Individual nucleotides
are arranged in long strands, which match up with their complimentary strand (the nucleotides containing the sequence of bases that pair up with the bases on the first strand) to form a double-helix.
Molecular machines read specific instruction-sequences from the DNA strand (transcription
). These transcribed instruction-sequences are copied to, and conveyed in mRNA
. They are used as blueprints to build proteins, which are the three-dimensional components used to produce all biological matter.
The three-dimensional assemblies of proteins are constructed from the 20 amino-acids
by a set of intracellular molecular machines, which follow the instructions encoded and copied into mRNA
from sub-sections of DNA.