Origins of Life on Earth
SC.912.L.15.8
Describe the scientific
explanations of the origin
of life on Earth.
Source: http://satirizingscientism.blogspot.com/2013/05/creation-of-life-la-campbells-lablake.html.
What do I need to know?
 Students will describe scientific
explanations of the origin of life on
Earth.
 Students will identify situations or
conditions contributing to the origin
of life on Earth.
Theories on the Origin of
Life on Earth
•Extraterrestrial theory: The
first life or building blocks of
life arrived came to Earth on
asteroids or meteors that
collided with Earth’s surface.
•Primordial ooze/Ancient soup
theory: The mixing of
chemicals in the atmosphere
and oceans and the energy in
lightning led to the formation
of organic compounds (nucleic
acids, proteins, lipids). These
compounds eventually gave
rise to the first life on Earth
First proposed by Oparin and
Haldane independently.
Testing the Ancient Soup
Theory
•Stanley Miller and Harold
Urey conducted a famous
experiment in which they
mimic the conditions of
Earth’s early atmosphere in a
closed container. They then
added an electric spark to
mimic lighting. They found
amino acids and other simple
organic compounds had
formed. This supported the
idea that life could of formed
from the synthesis of organic
compounds (ancient soup
theory).
Endosymbiotic Theory
•Endosymbioitc theory:
Proposed by Lynn
Margulis, this theory
describe the formation
of the eukaryotic cell. It
proposes that the
eukaryotic cell is a
result of the
combination of multiple
prokaryotic cells that
had formed a symbiotic
relationship.
Conditions of early earth
•Early earth was very hot, evaporating the liquid
water into the atmosphere. However, as the earth
cooled, gravity-trapped water vapor condensed,
fell as rain, and did not boil away but remained
impounded in pools that became lakes and
oceans. It was also believed that tectonic activity
caused many volcanic eruptions at that time.
From present-day volcanoes, we know that when
they erupt, they release carbon dioxide, nitrogen,
and a host of non-oxygen gases. In addition,
with no protecting atmosphere, the earth was
constantly bombarded with meteorites and other
space debris still in circulation from the big
bang. From current astronomical research, we
know that meteorites can carry ice and other
compounds, including carbon-based compounds.
Researchers believe, therefore, that early Earth's
atmosphere consisted of water vapor, carbon
dioxide, carbon monoxide, hydrogen, nitrogen,
ammonia, and methane.
Read more: Origin of Life: Early Earth Environment |
Infoplease.com
http://www.infoplease.com/cig/biology/early-earthenvironment.html#ixzz36uOKdDU9
Show What You Know
 One of the accepted scientific theories
describing the origin of life on Earth is
known as chemical evolution. According
to this theory, which of the following
events would need to occur first for life
to evolve?
A. onset of photosynthesis
B. origin of genetic material
C. synthesis of organic molecules
D. formation of the plasma membrane
Show What You Know
 The endosymbiotic theory proposes that eukaryotic
cells arose from living communities formed by the
merging of prokaryotic organisms and their hosts.
Which of the following is the best evidence to
support the endosymbiotic theory?
A. Mitochondria and chloroplasts contain DNA
similar to bacterial DNA.
B. Both prokaryotic and eukaryotic organisms
require oxygen in order to use energy.
C. Bacteria, mitochondria, and chloroplasts all
divide by mitosis, while the cells containing
them divide by binary fission.
D. Bacteria and mitochondria contain many
features that are similar to each other but
different from those of chloroplasts.
Show What You Know
 According the the hypothesis of Oparin and
the subsequent experiments of Miller and
Urey, which of the following situations
contributed to the origin of life on Earth?
A. Organic compounds formed from
meteorites that had fallen to Earth.
B. Cells evolved in an environment lacking
oxygen.
C. Organic compounds formed from gases
available in the atmosphere.
D. Cells evolved from large prokaryotic
cells that engulfed smaller prokaryotic
cells.
Show What You Know
 According the the hypothesis of Oparin and the
subsequent experiments of Miller and Urey,
which of the following situations contributed to
the origin of life on Earth?
A. Organic compounds formed from meteorites
that had fallen to Earth.
B. Cells evolved in an environment lacking
oxygen.
C. Organic compounds formed from gases
available in the atmosphere.
D. Cells evolved from large prokaryotic cells
that engulfed smaller prokaryotic cells.