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Evolution
FYOS
Lecture 4
C and H2O for alien life!
Common characteristics of Life
Biologists have identified at least six key features that appear to be shared by
nearly all of living organisms on Earth.
o Order
o Reproduction
o Growth and Development
o Energy Utilization
o Response
o Evolutionary Adaptation
Characteristics of
Life
• Order
• Reproduction
• Growth and Development
• Energy Utilization
• Response
• Evolutionary Adaptation
Biologists have identified at least six key
features that appear to be shared by nearly all
of living organisms on Earth.
Order : all living organisms exhibit order in their
internal structure.
molecules in living cells
are not scattered
randomly but instead
arranged in specific
patterns to make cell
structures.
Characteristics of
Life
• Order
• Reproduction
• Growth and Development
• Energy Utilization
Biologists have identified at least six key
features that appear to be shared by most or all
of living organisms on Earth.
Order : all living organisms exhibit order in their
internal structure.
However, snow
flakes, for
example, show
remarkable
structures also.
• Response
• Evolutionary Adaptation
But, snow flakes
are not alive!
Characteristics of
Life
• Order
• Reproduction
• Growth and Development
• Energy Utilization
Biologists have identified at least six key
features that appear to be shared by most or all
of living organisms on Earth.
Order : all living organisms exhibit order in their
internal structure.
How about
galaxies?
Are they alive?
• Response
• Evolutionary Adaptation
Therefore, “order” is not sufficient condition
for life. But, it is a necessary condition.
Characteristics of
Life
Reproduction: Organisms reproduce their own
kind
• Order
• Reproduction
• Growth and Development
• Energy Utilization
• Response
• Evolutionary Adaptation
A single-celled organism (an amoeba) copying
its genetic material (DNA) and dividing into two
genetically identical cells.
Mule, Tigon, Liger, Computer virus?
Again, necessary condition, not sufficient!
Characteristics of
Life
• Order
• Growth and Development : Living organisms
grow and develop in patterns determined at
least by heredity
Growing embryos of
Costa Rican frog
• Reproduction
• Growth and Development
Heredity : passing on
characteristics from
one generation to next
• Energy Utilization
• Response
• Evolutionary Adaptation
Wild fires, crystal?
Again, necessary condition, not sufficient!
Characteristics of
Life
• Energy Utilization: Living organisms use
energy to fuel their activities
• Order
• Reproduction
• Growth and Development
• Energy Utilization
Tube worms near a deep sea volcanic vent.
• Response
Car?
• Evolutionary Adaptation
Again, necessary condition, not sufficient!
Characteristics of
Life
• Order
• Reproduction
• Growth and Development
• Response: Living organisms actively responds to
changes in its surroundings
A blacktail jackrabbit’s
ears flush with blood,
the blood
automatically
adjusted to maintain
a constant internal
temperature
• Energy Utilization
• Response
• Evolutionary Adaptation
Mercury in a thermometer?
Again, necessary condition, not sufficient!
Characteristics of
Life
• Evolutionary Adaptation: Life evolves in a
way to become adapted to its surrounding
white-tail ptarmigan
• Order
• Reproduction
• Growth and Development
Camo-moth
• Energy Utilization
• Response
• Evolutionary Adaptation
counter example?
Evolutionary
Adaptation
• Charles Darwin (1858)
2 undeniable facts an inescapable conclusion
Overproduction
 struggle for survival
Individual
variation
Natural
Selection
Heritable traits that enhance survival and
reproduction will become progressively more
common in succeeding generations!
An imaginary population of beetles of mixed color evolves into dark beetles.
DNA is the backbone of the Evolution!
Replicating the whole ~3 billion bases for human DNA takes only a few hours
About 1 wrong coupling in every ~1 billion bases!
Sickle-cell disease
• Just one base change in
one gene (Adenine 
Thymine)
• Most mutations are
harmful, but occasional
good mutations are
being picked up by
“natural selection”
• About 1 replication error in billion chances
Mutation
• Any change in the base
sequence of DNA
o
o
o
o
wrong base
deleted base
extra base
etc.
• Most of these errors have no effect
Why? about 95% of human DNA bases are “noncoding DNA”
Most significant change is from “deleted base”.
• Due to this “error”, every individual living
organism differ each other.
• Mutation = molecular engine of the
evolutionary adaption!
How did all these start in the
beginning?
Organic Building Blocks
Miller-Urey Experiment
Experiment to create amino acids
(1953)
methane
hydrogen
water
ammonia
the first experiment to test the theory about the evolution of prebiotic chemicals and
the origin of life on Earth.
How did the DNA world get started?
• Human DNA contains about 12 billion molecules
• even a primitive virus has about 1 million molecules
• many viruses use RNA instead of DNA as their genetic material
DNA from the start?
• Typical RNAs have 20-30 nucleotides…
• Some RNAs are known to be self-replicable
• RNAs are sufficiently simple so that several types of them could have been
created by “Miller-Urey”-type reactions.
• These RNAs were exposed to the natural selection
Pre-cells
• Molecular evolution would have been much more efficient if RNA and other
molecules are confined in a structure.
o Increasing the rate of reaction
o Isolating its content to facilitate natural selection among RNA molecules!
 If no such enclosure, enzyme created by the best RNA can help other RNAs.
Left: microscopic spheres made by cooling a warm solution of amino acids
Right : microscopic membranes made from lipids mixed with water (instantaneously formed!)
RNA cell?
Lipid pre-cell can form on
the surface of clay!
+
Very high chance of
making RNA on the
surface of clay with
membrane!!
• Right: lab experiment
shows RNA strands (red)
entrapped within a lipid
pre-cell (green circle)
made on the surface of
clay!
Chemistry on the early Earth
6 Presentations on Feb 15
• Convergent evolution
o R. Shrestha
o J. Hedley
• Human Evolution
o E. Clendening
o A. Breeden
• Panspermia
o Z. Rindik
o C. Starlcup