Download Origin of Life - stephen fleenor

Warm-Up (4/4)
Describe the essential
components of all cells on Earth.
Name
Date
Period
1D.1a: Scientific evidence supports the various models.
1D.1a.1: Primitive Earth provided inorganic precursors from which organic molecules
could have been synthesized due to the presence of available free energy and the
absence of a significant quantity of oxygen.
1D.1a.2: In turn, these molecules served as monomers or building blocks for the
formation of more complex molecules, including amino acids and nucleotides.
1D.1a.3: The joining of monomers produced polymers with the ability to replicate, store
and transfer information.
1D.1a.4: The complex reaction sets could have occurred in solution (organic soup
model) or as reactions on solid reactive surfaces.
1D.1a.5: The RNA World hypothesis proposes that RNA could have been the earliest
genetic material.
1D.2a: Geological evidence provides support for models of the origin of life on
Earth.
1D.2a.1: The Earth formed approximately 4.6 billion years ago (bya), and the
environment was too hostile for life until 3.9 bya, while the earliest fossil evidence for life
dates to 3.5 bya. Taken together, this evidence provides a plausible range of dates
when the origin of life could have occurred.
1D.2a.2: Chemical experiments have shown that it is possible to form complex organic
molecules from inorganic molecules in the absence of life.
1D.2b: Molecular and genetic evidence from extant and extinct organisms
indicates that all organisms on Earth share a common ancestral origin of life.
1D.2b.1: Scientific evidence includes molecular building blocks that are common to all
life forms.
1D.2b.2: Scientific evidence includes a common genetic code.
Origin of Life
Geological evidence supports life
forming between 3.9 and 3.5 billion
years ago.
billion
4.5
years ago
3.9
3.5
2.0
Origin of Life
Miller-Urey Experiment: biological
molecules formed spontaneously
with electricity and atmosphere
molecules.
early Earth molecules
Origin of Life
Miller-Urey Experiment: biological
molecules formed spontaneously
with electricity and atmosphere
molecules.
Hypothesis:
early biomolecules formed
into polymers (DNA, RNA,
proteins, and lipids)
Origin of Life
Miller-Urey Experiment: biological
molecules formed spontaneously
with electricity and atmosphere
molecules.
Hypothesis #1:
early biomolecules formed
into polymers (DNA, RNA,
proteins, and lipids)
These molecules began
self-replicating in water
(primordial soup model)
Origin of Life
Miller-Urey Experiment: biological
molecules formed spontaneously
with electricity and atmosphere
molecules.
Hypothesis #1:
early biomolecules formed
into polymers (DNA, RNA,
proteins, and lipids)
These molecules began
self-replicating in water
(primordial soup model)
-ORThey self-replicated on
solid surfaces.
Origin of Life
Hypothesis #2:
an asteroid carrying cells crashed into Earth.
Origin of Life
Hypothesis #3:
RNA World Hypothesis:
RNA acted as an enzyme
to replicate itself.
ribozymes are 3D RNAs
which catalyze reactions.
Origin of Life
Hypothesis #3:
RNA World Hypothesis:
RNA acted as an enzyme
to replicate itself.
ribozymes are 3D RNAs
which catalyze reactions.
The ribosome is a
ribozyme.
Critical Thinking Question #1
In 1952 Stanley Miller and Harold Urey
hypothesized that the building blocks of life
(nucleotides and amino acids) first formed from
precursor molecules in Earth’s early atmosphere.
To test this hypothesis, they introduced electric
shocks into a chamber filled with hydrogen gas,
ammonia, water and methane and discovered that
many amino acids could be spontaneously
synthesized. Describe an example of the kind of
data collected in the years after this experiment
which would cause the hypothesis to be revised
and new experiments to be conducted. (LO 1.28)
(LO 1.29)
Closure
On the piece of white paper from the
back, answer the following question:
Explain how you believe life first
originated on Earth and justify your
explanation with evidence. (LO 1.30) (LO
1.31)
Name
Date
Period
Scale
1 – 10