The Double Helix
According to Richard Dawkins,
the DNA molecule is
the genuine essence of all
life forms. In 1953 the structure of the
DNA
was described for the first
time by J. Watson and F. Crick: the double helix.
This double helix is composed of four different building blocks, the
so-called nucleotides. Each of the nucleotides consists of three subunits:
- A sugar (desoxyribose),
- A phosphate group and
- A chemical base (Adenine, Thymine, Cytosine or Guanine).
This explains the acronym
DNA: deoxyribonucleic acid.
The nucleotides bind in the middle of the helix as follows:
- Adenine (A) binds to Thymine (T)
- Cytosine (C) binds to Guanine (G)
This principle is fundamental to replication, as can be seen in the
above picture. Once the double helix is split, each strand can only be
re-completed in one way, namely via the above formulated binding principle,
hence two identical copies form. Since principle behind the binding forces
is pure (quantum) physics, there shall be no doubt that no magic is needed
for life to occur.
The order of the base pairs is important, as it codes for the generation
of proteins. Each triplet,
e.g. ACT, codes for an amino acid. By
chaining amino acids in a well-defined sequence, proteins are formed. All
proteins are formed this way, no exception.
In eukaryotes (organisms with a nucleus in their cells),
the
DNA is
confined to the cell nucleus, except for a small amount in the mitochondria,
the so-called
mtDNA.
The mitochondria float in the cells cytoplasm and produce
energy in the form of adenosine triphosphate
(
ATP) from sugars and oxygen.
