1. Warm-Up (4/4) Describe the essential components of all cells on Earth.
Name
Date
Period
Describe the essential components of all cells on Earth.

2. 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.

3. Origin of Life
Geological evidence supports life forming between 3.9 and 3.5 billion years ago.
Environment permits life
First fossil evidence of life
Earth is formed
First eukaryotes
billion years ago
4.5
3.9
3.5
2.0

4. Origin of Life
Miller-Urey Experiment: biological molecules formed spontaneously with electricity and atmosphere molecules.
early Earth molecules

5. 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)

6. 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)

7. 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)
-OR-
They self-replicated on solid surfaces.

8. an asteroid carrying cells crashed into Earth.
Origin of Life
Hypothesis #2:
an asteroid carrying cells crashed into Earth.

9. Origin of Life ribozymes are 3D RNAs which catalyze reactions.
Hypothesis #3:
RNA World Hypothesis: RNA acted as an enzyme to replicate itself.

10. Origin of Life ribozymes are 3D RNAs which catalyze reactions.
Hypothesis #3:
RNA World Hypothesis: RNA acted as an enzyme to replicate itself.
The ribosome is a ribozyme.

11. 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)

12. Closure
On the piece of white paper from the back, answer the following question:
Name
Date
Period
Explain how you believe life first originated on Earth and justify your explanation with evidence. (LO 1.30) (LO 1.31)
Scale 1 – 10