The current version of this
book has been written for non-scientists.
Our apologies for the slow pacing
and generalities, for those who are
already experts in some of the fields
we cover!
Here is a quick summary of the points in the book,
for those who don't want
to read it all:
1. The first self-replicating molecules start
in
a small volume
that is highly concentrated
(so polymerization
can happen with no
energy input).
This
micropuddle has
high concentrations of just two amino
acids and
two nucleotides.
2. Under
those conditions,
two simple
molecules can
first transcribe
proteins, and then
replicate genetic chains.
The system starts
with a single-molecule
reading frame that
codes for just two
amino acids.
3. Eventually
the entire
system can self-replicate,
and then
gradually spread
and adapt to less-ideal
conditions.
4. Early pre-RNA nucleotides take
an active role
in catalysis, thanks
to the chemical
advantages of aromatic
rings. The first metabolic enzymes were probably
a combination of
short nucleotide
chains, and very
small proteins.
5. RNA also acted as a helper
chain for
positioning
proteins, and for
other tasks.
6. Later,
the system adds
two amino acids
and two more
nucleic acids, via
assimilation of
two four-molecule
'organisms'.
7. One of these eight-molecule
organisms
happens to include
nucleotides with complementary
base
pairing,
which leads
to
the RNA world.
8. Organisms gradually add cell
membranes
and other
features
of living
cells.
9. Introns arise as
a way to
manage the difference
between protein-coding
RNA,
and other
RNA.
10. DNA eventually
becomes the
main genetic chain,
and RNA is relegated
to a more temporary
role in cell metabolism.
11. Eventually the
system shifts
to a wider reading
frame. With
more than four amino
acids, proteins eventually
become dominant,
though ribozymes
and RNA 'helper
chains' are still
used (and are still
present in modern
life, stored in introns).
12. Later, cells start using repetitive
DNA as
'data'
to
specify cell
structures,
probably using
a
single reading
frame. The data starts
out in introns,
but for longer
scripts, transposons arise
as
a way to manage
and deliver
script DNA to
the appropriate
genes.
13. Almost all genetic inheritance
in multi-cellular
organisms
happens in the repetitive
script
DNA (2,000,000 +/- 'script genes' stored
in transposons,
vs 23,000 +/-
protein coding
genes).
14. Replication slippage is
the primary
driving force
for small
evolutionary changes.
Changes in
'script
ID' are the
primary driving
force for large
changes.
