Transcript Some Major Themes

MCB 419 Spring 2016
Part I:
emergence of
life on earth
evolution of
intelligence
Note for MCB 419 students:
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Spiral timeline: evolution of life on Earth
Each loop represents
approx. 0.5 billion years;
the final 0.5 billion years
is expanded to show
more detail.
Stellar nucleosynthesis begins
~ 13 BYA
Origin of universe: ~ 13.8
Formation of our solar system including planet Earth:
~ 4.5 BYA
Life is highly ordered
How does order
arise from disorder?
4 BYA: “primordial soup”
contains the building blocks of life
Protocell (hypothesis)
The chemoton (Ganti, 1984).
The metabolic subsystem, with
intermediates Ai, is
an autocatalytic chemical cycle,
consuming X as nutrient and
producing Y as waste material;
pV, is a polymer of n molecules
of V', which undergoes template
replication; R is a
condensation byproduct of this
replication, needed to turn T'
into T, the membranogenic
molecule; the symbol T,
represents a bilayer membrane
composed of m units made of T
molecules. It can be shown that
such a system can grow and
divide spontaneously.
fossil cyanobacteria
living cyanobacteria
Life appears on Earth: ~ 3.5–4.0 BYA
(modified from Wikipedia) The earliest life appears … possibly derived from selfreproducing RNA molecules. Replication requires resources like energy, space, and
smaller building blocks, which soon become limited, resulting in competition, with
natural selection favoring those systems which are more efficient at replication. The
replicators develop enclosing membranes which provide a stable physical and chemical
environment conducive to their replication.
http://en.wikipedia.org/wiki/Timeline_of_evolutionary_history_of_life