1. The origin of living systems is explained by natural processes.

2. There are several hypotheses about the natural origin of life on Earth, each with supporting scientific evidence
1.D.1

3. Earth was formed about 4.6 bya
Life on Earth emerged about 3.8 bya
For the first ¾ of Earth’s history, all organisms were microscopic and unicellular
Environment too hostile for life until 3.8 bya
Geologic clock compares Earth’s history with 24-hour clock
The geological time scale (GTS) is a system of chronological dating that relates geological strata to time, and is used to describe the timing and relationships of events that have occurred during Earth's history.
Earliest fossils 3.5 bya, ~18:00:00
Humans = 0:1:15

4. How is life on Earth documented?
Fossil record
Relative dating
Radiometric dating
Fossil = sequence in which fossils appear in the layers of Earth’s surface
Relative = order of rock strata
Radiometric = decay of radioactive isotopes to determine fossil/rock age

5. Early conditions of Earth have been simulated in lab experiments
Oparin and Haldane “Primordial Soup” theory
Early atmosphere was thick with little no oxygen
Energy was provided from lightening and UV radiation
Simple organic compounds were formed
Early Earth had a chemically reducing atmosphere
When exposed to energy, monomers were formed
These compounds were concentrated at various locations
By transformation, more complex polymers (life) developed (

6. Early conditions of Earth have been simulated in lab experiments (cotd)
Miller and Urey tested this hypothesis
A variety of amino acids were produced
Showed that abiotic synthesis of organic molecules is possible
Amino acids = building blocks of proteins
Water vapor, methane, ammonia, and hydrogen
Cooled to collect condensation in trap

7. The joining of these monomers produced polymers
RNA World Theory states that self-replicating RNA was the first genetic material
Some RNAs work as enzymes
Some viruses use RNA for heredity
RNA required for some fundamental functions of the cell
Either within the primordial soup itself, or on biogenic surfaces such as clay, which would act like an enzyme to join monomers together
The RNA world hypothesis proposes that life based on ribonucleic acid (RNA) pre-dates the current world of life based on deoxyribonucleic acid (DNA), RNA and proteins.
Monomers = molecules that are able to bond into long chains

8. Be Able To
1.27 Describe a scientific hypothesis about the origin of life on Earth.
1.28 Evaluate scientific questions based on hypotheses about the origin of life on Earth.
1.29 Describe the reasons for revisions of scientific hypotheses of the origin of life on Earth.
1.30 Evaluate scientific hypotheses about the origin of life on Earth.
1.31 Evaluate the accuracy and legitimacy of data to answer scientific questions about the origin of life on Earth.