Origin of Life Hypotheses 4 5 bya Earth

Origin of Life Hypotheses

4. 5 bya: Earth Forms I. Earth History

I. Earth History - Earliest Atmosphere - probably of volcanic origin Gases produced were probably similar to those created by modern volcanoes (H 2 O, CO 2, SO 2, CO, S 2, Cl 2, N 2, H 2) and NH 3 and CH 4

4. 0 bya: Oldest Rocks 4. 5 bya: Earth Forms I. Earth History

4. 0 bya: Oldest Rocks 3. 5 bya: Oldest Fossils 4. 5 bya: Earth Forms I. Earth History

4. 0 bya: Oldest Rocks 3. 5 bya: Oldest Fossils 4. 5 bya: Earth Forms I. Earth History Stromatolites - communities of layered 'bacteria'

2. 3 -2. 0 bya: Oxygen in Atmosphere 4. 0 bya: Oldest Rocks 3. 4 bya: Oldest Fossils 4. 5 bya: Earth Forms I. Earth History

1. 8 bya: first eukaryote 2. 3 -2. 0 bya: Oxygen 4. 0 bya: Oldest Rocks 3. 4 bya: Oldest Fossils 4. 5 bya: Earth Forms I. Earth History

0. 9 bya: first animals 1. 8 bya: first eukaryote 2. 3 -2. 0 bya: Oxygen 4. 0 bya: Oldest Rocks 3. 4 bya: Oldest Fossils 4. 5 bya: Earth Forms I. Earth History

0. 5 bya: Cambrian 0. 9 bya: first animals 1. 8 bya: first eukaryote 2. 3 -2. 0 bya: Oxygen 4. 0 bya: Oldest Rocks 3. 4 bya: Oldest Fossils 4. 5 bya: Earth Forms I. Earth History

0. 5 bya: Cambrian 0. 24 bya: Mesozoic 0. 9 bya: first animals 1. 8 bya: first eukaryote 2. 3 -2. 0 bya: Oxygen 4. 0 bya: Oldest Rocks 3. 4 bya: Oldest Fossils 4. 5 bya: Earth Forms I. Earth History

0. 5 bya: Cambrian 0. 24 bya: Mesozoic 0. 065 bya: Cenozoic 0. 9 bya: first animals 1. 8 bya: first eukaryote 2. 3 -2. 0 bya: Oxygen 4. 0 bya: Oldest Rocks 3. 4 bya: Oldest Fossils 4. 5 bya: Earth Forms I. Earth History

0. 5 bya: Cambrian 0. 24 bya: Mesozoic 0. 065 bya: Cenozoic 0. 9 bya: first animals 1. 8 bya: first eukaryote 2. 3 -2. 0 bya: Oxygen 4. 0 bya: Oldest Rocks 3. 4 bya: Oldest Fossils 4. 5 bya: Earth Forms I. Earth History 4. 5 million to present (1/1000 th of earth history)

II. Origin of Life Hypotheses - Oparin-Haldane Hypothesis (1924): - in a reducing atmosphere, biomonomers would form spontaneously Aleksandr Oparin (1894 -1980) J. B. S. Haldane (1892 -1964)

II. Origin of Life Hypotheses - Oparin-Haldane Hypothesis (1924): - in a reducing atmosphere, biomonomers would form spontaneously - Miller-Urey (1953) all biologically important monomers have been produced by these experiments, even while changing gas composition and energy sources

II. Origin of Life Hypotheses - Oparin-Haldane Hypothesis (1924): - in a reducing atmosphere, biomonomers would form spontaneously - Miller-Urey (1953) - Sydney Fox - 1970 - polymerized protein microspheres

II. Origin of Life Hypotheses - Oparin-Haldane Hypothesis (1924): - in a reducing atmosphere, biomonomers would form spontaneously - Miller-Urey (1953) - Sydney Fox - 1970 - polymerized protein microspheres - Cairns-Smith (1960 -70) - clays as templates for non-random polymerization - 1969 - Murcheson meteorite - amino acids present; some not found on Earth. To date, 74 meteoric AA's. - 2004 - Szostak - clays could catalyze formation of RNA's

III. Acquiring the Characteristics of Life A. Three Primary Attributes: - Barrier (phospholipid membrane) - Metabolism (reaction pathways) - Genetic System

III. Acquiring the Characteristics of Life B. Barrier (phospholipid membrane) - form spontaneously in aqueous solutions

III. Acquiring the Characteristics of Life C. Metabolic Pathways - problem: how can pathways with useless intermediates evolve? These represent 'maladaptive valleys', don't they? A B C D How do you get from A to E, if B, C, and D are non-functional? E

III. Acquiring the Characteristics of Life C. Metabolic Pathways - Solution - reverse evolution A B C D E

III. Acquiring the Characteristics of Life C. Metabolic Pathways - Solution - reverse evolution suppose E is a useful molecule, initially available in the env. E

III. Acquiring the Characteristics of Life C. Metabolic Pathways - Solution - reverse evolution suppose E is a useful molecule, initially available in the env. As protocells gobble it up, the concentration drops. E

III. Acquiring the Characteristics of Life C. Metabolic Pathways - Solution - reverse evolution D Anything that can absorb something else (D) and MAKE E is at a selective advantage. . . E

III. Acquiring the Characteristics of Life C. Metabolic Pathways - Solution - reverse evolution D Anything that can absorb something else (D) and MAKE E is at a selective advantage. . . but over time, D may drop in concentration. . . E

III. Acquiring the Characteristics of Life C. Metabolic Pathways - Solution - reverse evolution C D So, anything that can absorb C and then make D and E will be selected for. . . E

III. Acquiring the Characteristics of Life C. Metabolic Pathways - Solution - reverse evolution A B C D and so on until a complete pathway evolves. E