which uses up and down of temperature for base pairs disruption and formation. This
type of circumstances may be occurred in sea shore of the primitive Earth.
There is a mutual relationship between DNA and protein because biosynthesis of
protein requires genetic information on DNA and enzymes for DNA replication
(DNA polymerase. However, in the RNA world catalytic activity of enzyme protein)
is substituted by ribozyme. Coupling of amino acid and codon on DNA should be
elucidated. In the present living organisms on the earth, the coupling between
mRNA (transcripted codon information from DNA) and corresponding amino acid
is mediated by aminoacyl-tRNA having anti-codon and corresponding amino acid.
This coupling is mediated by amino-acyl tRNA synthetase that recognizes amino
acid and corresponding tRNA having anticodon of the amino acid. However, the
origin of this system and evolution to amino-acyl tRNA synthetase is still unclear.
1.1.4 Evolution as Progress of Energy Metabolic System
Evolution of metabolic pathway in living organisms on the earth was proposed by
Horrowitz from viewpoint of energy usage [5]. In the ocean of primitive earth, there
O
H N
CH3
O
H
N
H
N
N
N
C1’
H
O
N
N
N
H
O
N
H
N
N
N
N
H
H
C1’
C1’
C1’
A-T pair
E=-5.88 kcal/mol
G-T pair
E=-19.18 kcal/mol
Fig. 1.3 Watson-Crick base pair of DNA
Watson-Crick base pair is molecular basis for heredity of living organisms
6
1 Physics in the Origin of Life