Transcript Life Origins

In the Beginning, There Was -
That Matter
The BIG
In a VERY
then
spreads
BANG!!
SHORT TIME
A LOT
is sucked
from
(nanoseconds?),
back that
in = site
Massive
throughout
all Matter in
Black Hole
KaSpace.
“our” Universe
remains at
Boom!
is Formed from
Center!
All Matter
Energy in a
comes from
The
Rest
of
the
Matter?
The
Universe
massive
Approx
that original
has
been
Expanding
ever
since!
explosion.
13+ bya!!
event!
Fast at the Beginning, Slower Now.
NOTHING?!
(i.e., No Matter = No Stuff!)
But Very Quickly and by NOW, There is But There Are:
Scattered Random
clusters of Dust!
Dust = Matter!!
Matter = Gravity
Gravity = Force Inwards
Pulls Dust Together
UNTIL:
Not Much!
Cosmic Dust, Dark Matter, etc…
In OUR Beginning, There Were ONLY Leftovers!
Just Cosmic Dust
Looking for a Source of
Gravity – An Accident
that it happened Here!
(or anywhere else for
that matter)
Really is Dust to Dust!
The Swirling local dust cloud accumulated around a slightly
larger collection until its center collected enough “critical mass”
to – Boom! – form a Star! The Planets were neighbor collections
of hot gas and dust that coalesced in orbit around that Star that
became our SUN!
~ 5.0 bya
Got Dust
and Gas!!
Circling
Cosmic Dust
begins to
Collect into
discrete
Groups.
Smaller Collections
“sweep up” dust
orbiting the Sun to
form the various
Planets.
Gravity!!
But ROTATING
around the SUN!
MOST of
the Matter
collects into
the Central
Body as the
SUN!
Enough
Matter =
Enough
Gravity =
Fusion =
Radiation!
Energy
Source.
This Takes TIME! – The Solar
System is apparently less than
5 billion years old! Based on
the spectrum of the SUN. A
common number is:
4.6 Billion Years Old!
The Beginning!
The Earth begins to solidify,
and thus form, at approximately
4.6+ billion years ago!
LONG TIME TO GO!
Every time debris/meteors/comets/”stuff” hits the Earth, it imparts
energy to our planet. The theory is that during the “early age” of
the Earth, it was hit often and by large bodies – so it would
solidify and re-melt over and over as the Earth “sweeps” up the
matter in “its” Orbit.
Despite “forming” more than 4.5 bya, the Earth did not
permanently solidify with solid rocks until about 4.0 billion years
ago (bya).
The Oldest Known Objects
on Earth are Zircon
Crystals embedded in
various rocks. 4.2+ bya!
The Oldest Known Rocks on
Earth are dated to
approximately 4.0 bya.
See the Crystals?!
Almost every “old” rock dated – Moon rocks, Meteors = 4.4-4.5+ bya!
Actual Rocks are
not permanent until
approx. 4.0 bya.
Granite “melts” at
about 1100°C.
The Impact Energy is
enough to repeatedly
Melt the Earth during its
early history.
Oldest Dated
Substances = Zircon
Crystals at approx.
4.2 bya.
Zircon “melts” at
about 1750°C.
Solidifies FIRST!
The Early Earth - Not a
Vacation Site! Unstable!
Unstable and Unsurvivable by Life!
No H2O – No Large Organic Molecules!
Volcanic?! Hot! Acidic?!
Only Simple, non-reactive
Molecules Exist in the
Atmosphere due to the Heat.
CO2, H2, CH4, N2, simple acids.
Rain! Have to have it!
Aaaaaahhh! WATER!
But, by 3.9 bya, water
appears as the Earth cools
and rain introduces H2O to
the Earth!
The Universal Solvent!
All of the H and O is already
present, but not stable
enough to form and stay in
the atmosphere!
Finally Cool Enough!
As the conditions cool,
Water (and thus Rain) would
have appeared because H2O
is MORE STABLE than H2 or
O2 separately. Virtually ALL
of the Water on Earth would
have been formed then.
DUST
As Water
Levels
Increase.
R
A
I
N
F
A
L
L
!
According to Chemical
Weathering of the rocks =
about 3.9 bya!
Weathering = Water!!
Volcanic activity would have been
significant on the unstable Earth. This
would have ejected gas, ash, and debris
into the Early Atmosphere.
The Hot and Chemically Active
Atmosphere is important to the
development of Living Chemistry.
Early Life!
The First Fossils date to approximately 3.5 bya, but they are very
similar to some modern bacteria called Cyanobacteria (= blue-green
algae). These are large and colonial bacteria that would fossilize well,
but are too advanced to be first! We will get back to Them!!
The first evidence of life is the rare appearance of organic molecules in
layers of rocks dating from 3.8 bya.
Organic Molecules in significant amounts are generally accepted to occur only
in living things. Why?!
The Archaebacteria (Archae =
Ancient).
st
1
These are the most primitive
living things and are very
different from other bacteria.
Thought to be descendents of
early forms of life on Earth!
No Fossil Record ! Too
small and simple.
Archaebacteria – many live in very hostile environments and
are commonly called “Extremophiles”.
They are Chemosynthetic – They have the ability to get energy
and matter from free chemicals in their environments. Often live
in hot springs, oozy swamps, thermal vents, or other harsh
environments thought to be similar to the early Earth.
Such an environment would be rich in high-energy chemicals
from volcanic activity!
Many are Anaerobic! They cannot live in the
presence of oxygen. That is what they originally
evolved in! There are three basic types of
Archaebacteria: Salt, Hot, Anaerobic. All
suggestive of the Early Earth!
3.5 bya! Cyanobacteria are Better!
They are Photosynthetic! They are colored because they
possess what? That changes everything on the Earth because
Photosynthesis does what?
They are more complex and can specialize for their function!
Where are they found in a Food Web?!
With the Evolution of Photosynthesis (Food = Energy!),
true ecosystems can develop and bacteria diversify into all
possible niches.
Bacteria can exploit almost every niche!!
The AGE of PROKARYOTES!! All Sorts of Bacteria!
SUNLIGHT!!
Remember!
THE AVAILABLE
ENERGY SOURCE!
O2
O2
O2
O2
CO2 is used to make
Glucose. So, Producers
USE it!
O2 is a released Byproduct!
CO2
Ocean
Ocean
Ocean
Ocean
Ocean
PHOTOSYNTHESIS!!
THE ENERGY COLLECTING
PROCESS in Producers.
C
Life CANNOT Thrive on Earth until
PhotoAutoTrophs Evolve to produce
Food.
C
Limiting Factor!
C
C
O
C
C
Ocean
Ocean
O2 is very reactive and
cannot exist in the Early
Atmosphere – Why Not?!
Until Producers start
making O2 constantly, it
will not be present in the
Atmosphere.
Organisms Change Environments!
The Important Change occurs when OXYGEN becomes available
in the Atmosphere due to Photosynthesis!!
AEROBIC RESPIRATION is better than Anaerobic Respiration!
Why?!
This leads to the evolution and origins of the Eukaryotes around
1.5 bya.
Eukaryotes are larger and can specialize more
because of those organelles.
Evidence of Oxygen in Banded Iron
Formations mostly from 2.6 to 1.7
bya.
Before
Photosynthesis – No
or little free O2.
O2
Levels
Banded Iron Formations.
O2 Present!
Permanent
O2 present
= Aerobic
Possible
Now!
Rises after
appearance of
Cyanobacteria.
Oxidation of Iron = Rust!
Geologic Time
O2 disappears.
Layers of
Rusting
depend on
O2 !
Anaerobic Works, but is
Inefficient.
Those organisms tend to stay small
and simple – usually bacteria!
Now, they are restricted to rare
environments that lack Oxygen.
They Carry Out?
O2
is
Important!!
O2 leads to AEROBIC Respiration which is
Dramatically more Efficient! How Much More?!
Now, Cells are not restricted in size and
complexity! They can do More Things!
EUKARYOTES!
Have a Nucleus (why?) and many Internal Organelles (why?).
Are More Capable and Active Cells – Larger and better able to do
certain things than bacteria.
And you remember how they got that way – Right?!
ENDOSYMBIOSIS!! Literally means “inside” and “living together”.
Mitochondria and Chloroplasts were originally independent bacteria, but
they successfully entered and became parts of the Eukaryotic cell.
Mitochondria = ATP!!, Chloroplasts = Photosynthesis!!
The Age of Prokaryotes = Bacteria!
3.8bya to 1.5 bya!
Large “Pre”
Eukaryotic Cell!
Why “Eukaryotic”?
Once State –ofthe-Art Cells
Now “FOOD”!
BUT! Among all of those Prokaryotes are
SOME that have developed AEROBIC
RESPIRATION!!!! Huge Advantage
because:
Why
Heterotrophic?
How Much ATP?
The Age of Eukaryotes!
Appear approx 1 - 1.5 bya!
Larger Multi-Purpose
Successful Cells! Advanced!!
Now What?!
BUT! Among all of those Prokaryotes are
SOME that can perform
PHOTOSYNTHESIS!!!! Huge Advantage
because:
Eukaryotes EVOLVE TOO!
?
Eukaryotes thrive as Unicellular Organisms, but
really find success as Large Multicellular
Organisms!!
?
SUCCESSION!
Life is restricted to Aquatic Environments throughout this time
because of damaging UV radiation.
Water absorbs this radiation and thus protects aquatic
organisms.
But Terrestrial environments existed if there was atmospheric
protection. What develops in the Atmosphere that protects the
Earth form UV radiation?
Ozone becomes a thick enough layer for living
in air by approximately 450 mya. Plants go first,
followed by animals (=amphibians). Why?
KEEPING TRACK of CHANGE!
Every ERA and PERIOD is distinguished by different events
and/or types of organisms.
The divisions might
refer to Major
EXTINCTIONS such
as the CretaceousTertiary Boundary
when Dinosaurs
suddenly
disappeared, of the
Permian Boundary
when over 90% of all
known life
disappeared.
Or to Evolution of
New Forms of Life
such as the
appearance of
Animals at the
beginning of the
Cambrian Era.
For Instance! You are Supposed to know what organisms are
dominant in the various Eras (not Periods!).
Cenozoic Era
The Age of Mammals.
and Birds, etc…
NEWLY Evolved and
Still Dominant!!
For Instance! You are Supposed to know what organisms are
dominant in the various Eras (not Periods!).
Mesozoic Era
The Age of Reptiles. and
Flowering Plants, Insects,
etc…
NEWLY evolved, but
eventually lose!
For Instance! You are Supposed to know what organisms are
dominant in the various Eras (not Periods!).
Paleozoic Era
The Age of Complex
Organisms. Appear
Suddenly at Cambrian
Boundary = Line!!
OXYGEN!
For Instance! You are Supposed to know what organisms are
dominant in the various Eras (not Periods!).
PreCambrian
The Age of Cells and
simple Animals/Algae.
Still Evolving!
FOSSILS
Describing Change in
Organisms.
Fossils are essential to
describing and following this
evolutionary change. Only
Fossils can provide direct
evidence of how organisms
change!
That is because they represent
real organisms at different times
from the past.
Can compare them to each other
and to modern organisms to
note how organisms change
through time
Only Sedimentary Rocks work! Why?
What has to happen for a fossil to form?
Different types of Fossils can be formed. They can each
tell us different things about organisms of the past!
Types of Fossils – Trace Fossil
Trace Fossils do not show the organism,
but some representation of what the
organism did in the past
Dinosaur Footprints and Trackways. How do they
walk? How fast? In Groups? Reproductive Nests?
Trilobite Trackway.
Fossilized imprint of
how they move in the
Sediment.
Types of Fossils – Cast Fossil
Casts are penetrated tissues of the
organism that have been replaced with
sediments. Their shape and structure is
preserved. Can be compared to study
evolution.
Archeopteryx – one of
the earliest “birds”.
Microraptor – a theropod dinosaur
discovered in China that has feathers and
closely resembles Archeopteryx, but is a
Dinosaur.
Types of Fossils – Mold Fossil
Molds are formed as the surfaces of the
organism are covered and preserved. This
can be the inside or the outside. They
show basic structures, but not the actual
organism.
Molds of a fossil snail and
ammonite. They can show
basic structure, curling
patterns, etc. But not the
internal features of the
organism.
Types of Fossils – Preserved Fossil
Actual Organism. Rare fossils that have
been actually maintained and can see the
original organism. DNA possibly!
Actual Insects
trapped in Amber.
Some are millions of
years old.
Soft Tissue
recovered from a
thigh bone of a T.
rex. It had
protein and DNA
in it!
Types of Fossils – Petrified Fossils
Slow mineral replacement of the tissues –
Usually Wood. Very precise replacement
so the structure of the organism can be
visualized.
If the conditions are right, fossils do not
have to be formed from just “hard”
tissues!
600 million
year-old softbodied
invertebrates
Dinosaur skin
Dinosaur
Internal
Organs
Dinosaur eggs and embryos
– evidence for life history patterns
and similarities with living
organisms
Not always Rock!
Mummified remains are even
better because they have soft
tissues that can be more
effectively dated. Also, they
have easily retrieved DNA that
can be tested for many things!
Wooly Mammoth - Tundra
Only specific and rare
conditions allow for this type
of preservation – namely cold
and/or dry environments.
Dog – Mountains in Peru
La Brea Tar Pits.
Fabulous Fossil remains – Lots, Intact, and
they show diversity of organisms present in
the area – entire ecosystems!
How can We Determine the Age of Fossils?
Relative Dating is based on Comparison of the
layers of the Rock. Older Fossils should be
where?
Rock layers in different areas can be correlated
based on the types of fossils found in them.
Some fossils are so common that they are used
to “date” rock layers world-wide. This allows
paleontologists to “date” fossils from different
parts of the world. INDEX FOSSILS!!
Younger!
Older!
Law of Superposition
How can We Determine the Age of Fossils?
Radiometric Dating provides actual, but approximate, ages for
some rock/fossil samples.
Radio (=radiation), Metric (=measure).
Radioactive materials decay into stable elements. So, if the rate
of decay and amount of these elements can be known/measured,
the age of the sample can be determined.
Radioactivity measures the
release of energy from the
atoms of the original
unstable substance. As
such, the atoms literally
change into new forms.
Often, one element into
another!
So, to begin
Original Result
0
100%
0%
1st 50%
50%
2nd 25%
75%
3rd 12.5%
87.5%
4th 6.25%
93.75%
5th 3.125% 96.875%
And so on until the
original amounts can
no longer be
measured
Important Point!
As the Radioactive material decays, it leaves “its” daughter
material behind. Therefore, you have to able to measure both to
see how much has transformed and determine how many halflives have elapsed.
R
Original Material
100%
A
D
I
O
A
C
T
One Half Life
50%
I
V
I
T
Y
!
Two Half Lives
25%
Three Half Lives
12.5%
Four = 6.25%
Five = 3.125%
Problem!
This can only be done in rocks that are
still intact = Igneous and Metamorphic
(that were originally igneous). Only they
have the original materials of the rocks
still present. The minerals are
crystallized and trapped!
Problem!
Sedimentary Rocks are made through the erosion and
thus destruction of the original rocks. They do not
contain original materials and thus cannot be reliably
dated Radiometrically.
But Vulcanism is a common phenomenon and
some igneous rock formations are usually
present. They can be dated!
Carbon-14
Carbon-14 dating is useful for relatively recent
fossils/artifacts. It is constantly made and
available in all living things.
Carbon-14 is integrated into plants as CO2. Since we know how much C-14
is normally present in living tissues, we can directly measure how old
something is based on the amount of C-14 is left!
If we know how much SHOULD be present, and can measure how
much IS still present, a likely absolute date is possible. C-14 has
a half-life of only 5730 years, so it can be used for materials as
old as about 50,000 years!
Known!
1 HL
2 HL
3 HL
?
4 HL
5 HL
Older Substances can be dated with isotopes that have longer
half-lives if they are present. Pick your Radioisotope!
Uranium-238 has a half-life of 4.5 billion years
Potassium-40 = 1.3 billion years / Thorium-230 = 75,000 years
Cobalt-60 = 5.26 years / Barium-139 = 86 minutes
The common belief until the 1600’s (what happened then?) was that
living things could develop via Spontaneous Generation. This accounted
for sudden appearance of organisms from the environment.
Until 1668 – Francesco Redi
First Recorded Biology Experiment – studied Biogenesis in response to
beliefs at the time that disease was caused by smell, the results of
infections, or other “bad” things, but not actual microorganisms.
Thus, they treated the results of the disease, but not the cause!
But not convincing for many! Only Flies after All!
The counter-argument then stressed that advanced organisms (like us)
are self-perpetuating, but minor – flies, maggots, microorganisms (newly
discovered by whom?) were still Spontaneous!
So, until 1765 – Lazzaro Spallanzani
Studied Biogenesis in broth, looking for the causes of spoiling in food due
to microorganisms. BIG ISSUE since the causes of spoilage in
prepared and stored foods was a major problem now during long
voyages. But, mostly examining Spontaneous Generation!
Like Redi, he discovered that
preventing entry of the living
causes of contamination could
ensure a sterile environment!
BUT – critics suggested that he
“killed” the Vital Force (=God?)
that creates life by boiling the
broth, and sealing the jars keeps
it out! So, still Spontaneous, but
his conditions are inappropriate!
VITAL FORCE becomes the problem in
demonstrating Biogenesis for the Skeptics!
So, critics of Biogenesis are still fighting into
the 1800’s! Vital Force becomes the
important factor for Spontaneous
Generation! It is in the Air!
Until 1864 – Louis Pasteur
Famous Swan-Neck Flask experiment
conclusively demonstrated that Only
Life can produce Life!
Very Clever experiment that allows Air
(= Vital Force) to enter and make
contact with the sterilized broth, but
still prevents the dust and
microorganisms to enter.
So, still sterile, but directly deals with
the criticism still lingering over
Spallanzani’s experiment.
So, if Life can Only come from Life, how did it all start in the First
Place?
First Thing – Have to have the Building Blocks of Life = Basic
Organic Compounds. Cannot Build without Supplies!
1924 – Alexander
Oparin
Suggested the idea of
Abiotic Synthesis of
Organic Compounds.
Published in 1936!
Basically, all of the molecules that are
required for life to form can be made under
the conditions of the Early Earth.
Hot! Chemically Reactive! Energetic!
He called it Primordial Soup!
Also suggested by J.B.S. Haldane in the 1920’s
So, if Life can Only come from Life, how did it all start in
the First Place?
But his idea was only an Observation!
What does a Hypothesis Need?!
1953 – Stanley Miller!
w/ Harold Urey
Developed a way to
“test” if Abiotic
Synthesis could occur.
The idea was to mix
together the
chemicals that
would have been
present in the early
Earth’s atmosphere
(very different than
today!) and apply
energy to see if any
chemical changes
occur.
So, if Life can Only come from Life, how did it all start in the First
Place?
2. A mock early atmosphere
3. An energy
source to
cause
reactions.
4. Chemicals
collected for 12 weeks.
1. Boiling Water to
start
5. Success! Various Organic
Molecules!
So, if Life can Only come from Life, how did it all start in the First
Place?
With Organic Compounds of all Types!
These Organic Compounds are Stable on their
Own! They are Made and Exist Spontaneously!!
Amino Acids and
Proteins.
Carbohydrates.
Nucleic Acids.
Stick together
Genetic
Can Self-Assemble and can bind to molecules that
and form different other molecules can “do things”
shapes with basic
and replicate =
functions.
Reproduce!
Fatty Acids.
Can form
Membranes by
themselves
that hold other
substances.
The Cell!
Cell Membranes make
themselves. So, if these
molecules can be produced
naturally, a “Protocell” will
form!
Proteins and Nucleic Acids
can also form by themselves,
carry out different functions,
and even self-replicate. If
that gets “in” the “cell” =
Potential Life!
Bear in Mind – Millions of Years!
This only has to happen once!
Then it all starts!
Non-Living
LIFE

Not Possible?!
So, We operate on the basic premise that Life (Cells) Only Come
from Pre-Existing Cells (Part of the Cell Theory – Remember?!).
BUT, Life had to develop at some point. How?
SO:
No  Way 
Non-Living
LIFE
But!
But!
But!
But!
Spontaneous
Organic
Molecules
necessary for
Life?
Organic
Molecules SelfAssemble!
Some
Molecules
Replicate and
even Resist
Change.
Can They Form
a ProtoCell with
certain aspects
of Living
Things?
Reproduction!
Pseudo-Life?
Homeostasis!
Not Yet Shown.
Possible!
Likely?
Inevitable!?!
More Stable
Together than
Separate!
Want to Be
Together!
Alive?!
The Science Approach is to break-down the process into steps
and investigate their possibilities. KISS!! Scientific Method!
One Step is Incredible. But Many Small Inevitable Steps??!!
Early Earth/Life Origins Quiz
Slideshow Fill-in-the-Blank
Question.
First set of Blanks on Paper!
One Pass – All Pictures from the
Early Earth/Life Origins Slide Show.
Ready?!
Not Huge Points – Let’s see how you do!
Early Earth/Life Origins Quiz
Slideshow Fill-in-the-Blank
Question.
First set of Blanks on Paper!
a.
What is the Object shown
to the Right?
Early Earth/Life Origins Quiz
Slideshow Fill-in-the-Blank
Question.
First set of Blanks on Paper!
b.
These are the first known
Photosynthetic
organisms.
What are they?
Early Earth/Life Origins Quiz
Slideshow Fill-in-the-Blank
Question.
First set of Blanks on Paper!
O2
c.
What does the presence
of O2 allow advanced
organisms to do?
is
Important!!
CO2
Early Earth/Life Origins Quiz
Slideshow Fill-in-the-Blank
Question.
First set of Blanks on Paper!
d.
The Geologic Time Scale
has lots of different
recognized Subunits.
What happens at each
defined line?
Early Earth/Life Origins Quiz
Slideshow Fill-in-the-Blank
Question.
First set of Blanks on Paper!
e.
An object still has 1/8 of
its original Carbon-14 in
its material.
How old is it?
Water
Vapor
H2
H2O