Download Evidence For Evolution File

I. Changes Through Time
A. The Beginning of Life
1. Origin of the Universe (13.7 BYA)
a) Many theories exist
b) Scientists favor the Big Bang Theory
which state that the universe began as a
dense concentration of matter smaller
than a speck of dust which exploded
outward violently
2. Origin of the Sun (10 BYA)
a) Clouds of molecules, made of hydrogen gas, began to
grow in mass which increased their gravity, which in
turn, attracted more hydrogen to increase their mass
b) These clouds increased to such a huge mass, that it’s
gravity smashed hydrogen molecules together,
triggering a Fusion Reaction. We call these fusion
reactions clouds Stars and one formed our Sun
3. Origin of Earth
a) Clouds of matter caught
in the Sun’s
gravitational field began
forming Planets
b) Solid matter collected
into a dense core and
radioactive decay melted
the matter into a ball of
molten rock that we call
Earth
Earth at Birth (4.5 BYA)
c) Earth could not support life at
this time.
1.
2.
3.
4.
5.
Tidal waves of Lava
Poison gas atmosphere
Deadly ultraviolet rays
Constant meteorite bombardment
Frequent earthquakes
• Name 2 reasons why life could not support
life?
Relative Size of Inner Planets
Relative Size Outer Planets
Size of Planet Relative to the Sun
Size of Sun Relative to Other Stars
Our Sun Relative to the Largest Stars
4. Origin of Life (3.5 BYA)
a) The heat of the earth
slowly radiated away and the
atmosphere cooled below
the boiling point. Rain
formed the oceans
Abiogenesis- Spontaneous generation of Life.
Abiogenesis is NOT evolution
Russian Biochemist Alexander Oparin introduced a
plausible theory of chemical development of life in 1927
• What is abiogenesis?
b) Oparin’s Hypothesis
1. The early atmosphere contained hydrogen,
Methane, Ammonia and Water vapor
2. Violent atmospheric conditions caused much
lightning; heat from molten rock, and ultraviolet
radiation from the sun provided energy for
chemical reactions to take place
3. Organic molecules such as Amino acids, lipids
and nucleic acids accumulated in the oceans
forming an organic soup
4. The organic compounds developed into the first
cells which might have resembled anaerobic
bacteria
5. Global Famine and Toxic Waste
a) The first cells had plenty to eat; however, as
population size increased, food decreased
(Global Famine)
b) Fortunately, high amounts of ultraviolet
radiation caused a high rate of mutation and
cells capable of photosynthesis developed
c) These cynobacteria changed the earth’s
atmosphere by adding oxygen
d) Pure oxygen is toxic and highly reactive and it
built up in the atmosphere until it threatened all
live on earth (toxic waste)
e) Mutations created cells capable of respiration
which converted the oxygen to water
• What organism changed the
Earth’s oxygen content?
(according to Oparin)
B. Evidence for Oparin’s Hypothesis
1. Stanley Millers Experiment
• Miller created an
apparatus to simulate the
conditions on early earth
• After running his
“primitive earth
machine” for a few days,
miller found his “ocean”
teeming with amino acids
the building blocks of
protein!
2. Sidney Fox Experiment
• Fox heated and cooled
amino acids. And
found they formed
“cell-like” clump
called coacervates.
• Coacervates carry on
limited enzyme
activity
3) Leslie Orgel
• Orgel proved that
nucleotides of DNA
and RNA can
assemble under the
conditions of early
Earth
• Proposed that RNA
was the first genetic
material because it’s
can be auto catalytic
4) David Deamer
• Deamer mixed lipid
with DNA and
dehydrated them
and rehydrated
them and found that
they would form
membranes around
the DNA
What does DNA and RNA polynucleotides with
protein catalyzing chemical reactions in a lipid
membrane remind you of?
A cell of course!
But, scientists have only produced Coacervates in the lab
DNA replication requires enzymes and DNA is
required to make enzymes.
Therefore, current theory suggests that the first genetic
material was RNA because it can be auto catalytic
(RNA could catalyze its own replication.)
But, replication produces a complementary strand, not a
coding strand, so two replications would be required.
C. Evidence of Evolution
1. Direct evidence
of Evolution
comes from the
fossil record
Scientists who
interpret the
fossil record are
called
paleontologists
Fossil Record
1) Fossils- any evidence of a once living
thing
2) Fossil formation (a sequence of
improbable events) most often occurs in
sedimentary rock, where sand under great
pressure turns to rock
Types of Fossils
Imprints
Casts
Petrified
Molds
3) Types of Fossils
• Imprints- formed by impressions in rock
• Molds- depressions in rocks shaped like the
organisms
• Casts- where molds are filled with other
material leaving a fossil shaped like the
original structure
• Petrified fossils- where parts of an
organisms are replaced by minerals
b) Determining the Age of Fossils
1. By their position in the layers of
sedimentary rock
2. By using radioactive isotopes- materials
that decompose into decay elements at a
constant rate called a half-life
–
–
Carbon 14 half-life 5730
Uranium 238 half life 4.5 billion
•What is carbon
dating?
2. Indirect Evidence of Evolution
a. Comparative Biochemistry
Organisms with
similar protein
structure and similar
DNA sequences are
more closely related
than organisms with
different protein
structure and different
DNA sequences
Examine the following DNA sequences. Which two
of the three organisms is most closely related?
Organism A: GGT CTC AAT GTA ATC CAA TCC AGG
Organism B: GGT CAC ATT GTA ATG CAA TCG AGG
Organism C: GGA CTC ATT GTA ATC CGG TCC AGC
A & B Matches: 20 A & C Matches: 19 B & C Matches: 17
A & B are most closely related
b. Homologous
Bone Structures
Similar structures
found in different
organisms suggests
a common ancestry
c. Embryological Evidence
Organisms that
develop similarly
have common
genetic material
which controls
development which
in turn suggest
common ancestry
3. Geologic Time Scale