Presentation Details:
Slides: 14
Duration: 00:05:32
Filename: C:\Users\jpage\Documents\NCVPS Learning Objects\AP Biology\AP Biology Origin of Life Navigation to PPT
W\mod_9_originoflife.ppt
Presenter Details:
Published by Articulate® Presenter
www.articulate.com
Slide 1
Notes:
Origin of Life
In this presentation, we will explore various
theories on the origin of life. We will also explore
conditions of early earth and the evolution of
cells.
Duration: 00:00:09
Advance mode: Auto
Image attribution: By LadyofHats (Own work)
[CC0], via Wikimedia Commons
Slide 2
Notes:
Evolutionary Tree
Using fossil, biochemical and anatomical
evidence, we can create and evolutionary tree of
life. However, the origin of life on Earth is more
difficult to explain.
Duration: 00:00:11
Advance mode: Auto
Image attribution: By User:TimVickers, SVG
conversion by User:User_A1.User A1 at
en.wikipedia [Public domain], from Wikimedia
Commons
Slide 3
The Origin of Life is Hypothesis
Duration: 00:00:37
Advance mode: Auto
The Origin of Life is Hypothesis
 Special Creation


Was life created by a supernatural or
divine force?
not testable
 Extra-terrestrial Origin (panspermia)


Was the original source of organic
(carbon) materials comets & meteorites
striking early Earth?
testable
 Spontaneous Abiotic Origin


AP Biology
Published by Articulate® Presenter
Did life evolve spontaneously from
inorganic molecules?
testable
Notes:
Since no one was around 3.5 billion years ago,
any ideas about the origins of life are
hypothetical. However, scientific knowledge is
based on testable theories. Special creation is
widely accepted, especially in the US, but it is
not testable. Therefore it has no place as a
scientific hypothesis. However, the idea of extraterrestrial origins of life, or panspermia, does
have testable and credible evidence which
supports it. The idea of spontaneous abiotic
origin of life proposes that life evolved
spontaneously from inorganic molecules. This
hypothesis is also supported by evidence an has
www.articulate.com
been successfully tested.
Slide 4
Conditions on early Earth
Duration: 00:00:41
Advance mode: Auto
Notes:
It is unclear whether young Earth’s atmosphere
contained enough methane and ammonia to be
reducing. Growing evidence suggests that the
early atmosphere was made up primarily of
nitrogen and carbon dioxide and was neither
reducing nor oxidizing (electron–removing).
Miller–Urey–type experiments using such
atmospheres have not produced organic
molecules. Still, it is likely that small “pockets” of
the early atmosphere—perhaps near volcanic
openings—were reducing.
Instead of forming in the atmosphere, the first
organic compounds on Earth may have been
synthesized near submerged volcanoes and
deep–sea vents—weak points in Earth’s crust
where hot water and minerals gush into the
ocean.
Published by Articulate® Presenter
www.articulate.com
Slide 5
Origin of Organic Molecules
Duration: 00:00:29
Advance mode: Auto
Notes:
Two important experiments which tested the
abiotic origins of life were conducted by Oparin,
Haldane, and Miller & Urey.
Oparin and Haldane proposed the reducing
atmosphere hypothesis.
In 1953 Miller and Urey tested this hypothesis by
mixing a combination of gases and adding an
electrical spark. What resulted was a soup of
amino acids and adenine. We know these
compounds are important in creating proteins,
ATP, and nucleic acids.
Image attribution: By GYassineMrabetTalk✉
This vector image was created with Inkscape.
✓ The source code of this SVG is valid. (Own
work from Image:MUexperiment.png.) [GFDL
(http://www.gnu.org/copyleft/fdl.html) or CC-BYSA-3.0-2.5-2.0-1.0
(http://creativecommons.org/licenses/by-sa/3.0)],
via Wikimedia Commons
Slide 6
Stanley Miller
Duration: 00:00:05
Advance mode: Auto
Notes:
Stanley Miller was a professor at the University
of Chicago.
Image attribution: By Miller1999.jpg: Unknown
derivative work: Vojtech.dostal (Miller1999.jpg)
[Public domain], via Wikimedia Commons, and
See page for author [Public domain], via
Wikimedia Commons
Published by Articulate® Presenter
www.articulate.com
Slide 7
Key Events in Origin of Life
Duration: 00:00:55
Advance mode: Auto
Key Events in Origin of Life
 Origin of Cells (Protobionts)

lipid bubbles  separate inside from outside
 metabolism & reproduction
 Origin of Genetics


RNA is likely first genetic material
multiple functions: encodes information (selfreplicating), enzyme, regulatory molecule,
transport molecule (tRNA, mRNA)
 makes inheritance possible
 makes natural selection & evolution possible
 Origin of Eukaryotes

AP Biology
endosymbiosis
Notes:
Life is defined partly by two properties: accurate
replication and metabolism. Neither property can
exist without the other. Self–replicating
molecules and a metabolism–like source of the
building blocks must have appeared together.
How did that happen?
The necessary conditions for life may have been
met by protobionts, aggregates of abiotically
produced molecules surrounded by a membrane
or membrane–like structure. Protobionts exhibit
some of the properties associated with life,
including simple reproduction and metabolism,
as well as the maintenance of an internal
chemical environment different from that of their
surroundings.
Laboratory experiments demonstrate that
protobionts could have formed spontaneously
from abiotically produced organic compounds.
For example, small membrane–bounded droplets
called liposomes can form when lipids or other
organic molecules are added to water.
Slide 8
Timeline
Duration: 00:00:23
Advance mode: Auto
Notes:
Geologic evidence suggests that the Earth is 4.6
billion years old.
Fossil evidence suggest that life originated 3.5-4
bya, likely in the oceans.
At 2.7 bya the rise of atmospheric oxygen
coincided with the evolution of photosynthetic
bacteria.
Two bya the first eukaryotes appeared.
Image attribution: By LadyofHats (Own work)
[CC0], via Wikimedia Commons
Published by Articulate® Presenter
www.articulate.com
Slide 9
First Eukaryotes
Duration: 00:00:26
Advance mode: Auto
~2 bya
First Eukaryotes
 Development of internal membranes
create internal micro-environments
advantage: specialization = increase efficiency


 natural selection!
 Infolding of cell membranes lead to


Nuclear envelope and nucleus
ER (which surrounds the nucleus)
Notes:
The first eukaryotes evolved around 2 billion
years ago. The first step was the development
of internal membranes from the plasma
membranes. This created internal microclimates and created the advantage of
specialization. This step increased efficiency of
cell processes and was an important adaptation.
The infolding of the cell membranes lead to the
creation of the nuclear envelope and nucleus, as
well as the endoplasmic reticulum.
AP Biology
Slide 10
Endosymbiont Theory
Endosymbiont Theory
Duration: 00:00:40
Advance mode: Auto
 Theory proposed by Lynn Margulis suggesting that
eukaryotes evolved from a symbiotic relationship with
prokaryotic cells
 1st Endosymbiosis

origin of mitochondria

engulfed aerobic bacteria, but
did not digest them
mutually beneficial relationship

 natural selection!
 2nd Endosymbiosis



AP Biology
Published by Articulate® Presenter
origin of chloroplasts
engulfed photosynthetic bacteria,
but did not digest them
mutually beneficial relationship
 natural selection!
Notes:
The Endosymbiont theory suggests that
eukaryotic cells evolved from a symbiotic
relationship with prokaryotic cells. This theory
was developed in the late 1970’s by Lynn
Margulis. She suggests there were two
important symbiotic events.
The first endosymbiosis resulted in the origin of
mitochondria. A prokaryotic cell engulfed an
aerobic bacterial cell, but did not digest it.
Rather they developed a symbiotic relationship.
The second endosymbiosis resulted in the origin
of chloroplasts. In this case a photosynthetic
bacteria was engulfed, leading to photosynthetic,
eukaryotic cells.
www.articulate.com
Slide 11
Endosymbiosis
Notes:
Endosymbiosis
Here is a simplified image of symbiosis.
Duration: 00:00:04
Advance mode: Auto
Image attribution: By Signbrowser (Own work)
[CC0], via Wikimedia Commons
AP Biology
Slide 12
Theory of Endosymbiosis
Duration: 00:00:27
Advance mode: Auto
Notes:
Theory of Endosymbiosis
 Evidence

There are several lines of evidence supporting
the theory of endosymbiosis.
structural
 mitochondria & chloroplasts
First, structural evidence shows that
mitochondria and chloroplasts resemble bacterial
structure.
resemble bacterial structure

genetic
 mitochondria & chloroplasts
have their own circular DNA, like bacteria

functional
 mitochondria & chloroplasts
move freely within the cell
 mitochondria & chloroplasts
AP Biology
reproduce independently
from the cell
Lynn Margulis
Second, mitochondria and chloroplasts have
their own circular DNA, just like bacteria.
Third, mitochondria and chloroplasts move freely
about the cell and also reproduced
independently from the cell, via binary fission.
Image attribution: Taken by me during her
conference in La Coruña on november, 9, 2005
More available in
[http://www.flickr.com/photos/wicho/61549769/
my Flickr pages].
Published by Articulate® Presenter
www.articulate.com
Slide 13
Cambrian explosion
Duration: 00:00:17
Advance mode: Auto
Notes:
There have been several major extinction and
speciation events in geologic time. The most
significant speciation event was the Cambrian
Explosion, about 543 million years ago.
At this time, the majority of the animal phyla
appeared in the fossil record.
Image attribution: By Woudloper derivative work:
Hardwigg (File:Geologic_clock.jpg) [Public
domain], via Wikimedia Commons
Slide 14
Major events in geologic time
Duration: 00:00:07
Advance mode: Auto
Notes:
Here is a larger look at major events in geologic
time as they pertain to living things.
Image attribution: By Woudloper derivative work:
Hardwigg (File:Geologic_clock.jpg) [Public
domain], via Wikimedia Commons
Published by Articulate® Presenter
www.articulate.com