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Origin of Life on Earth. Conditions on early Earth made the origin of life possible Physical and chemical processes on Earth may have produces simple.

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Presentation on theme: "Origin of Life on Earth. Conditions on early Earth made the origin of life possible Physical and chemical processes on Earth may have produces simple."— Presentation transcript:

1 Origin of Life on Earth

2 Conditions on early Earth made the origin of life possible Physical and chemical processes on Earth may have produces simple cells on earth. The process of make these cells include: 1. Abiotic synthesis of small organic molecules 2. Joining of these small molecules into macromolecules 3. Packaging of molecules into protocells (Protobiants) 4. Origin of self-replicating molecules

3 Synthesis of Organic Compounds Earth’s early atmosphere likely contained water vapor and chemicals released by volcanic. (C0 2, N 2, Hydrogen Sulfide H 2 S, Sulfur Dioxide S 2 O) In the 1920s, A. I. Oparin and J. B. S. Haldane hypothesized that the early atmosphere was a reducing (Electron-Adding) environment. In 1953, Stanley Miller and Harold Urey conducted lab experiments that showed that the abiotic synthesis of organic molecules in a reducing atmosphere is possible Miller-Urey–type experiments demonstrate that organic molecules could have formed with various possible atmospheres

4 RNA monomers have been produced spontaneously from simple molecules. Amino acid polymerize when they are concentrated on hot sand, clay, or rock. This proved that is it possible for these molecules to function as a catalyst. Abiotic Synthesis of Macromolecules

5 Protocells Replication and metabolism are key properties of life and may have appeared together Protocells may have been fluid-filled vesicles with a membrane-like structure In water, lipids and other organic molecules can spontaneously form vesicles with a lipid bilayer Vesicles exhibit simple reproduction and metabolism and maintain an internal chemical environment

6 Figure 25.3 (a) Self-assembly Time (minutes) Precursor molecules plus montmorillonite clay Precursor molecules only Relative turbidity, an index of vesicle number 0 20  m (b) Reproduction(c) Absorption of RNA Vesicle boundary 1  m

7 RNA and Self-Replication The first genetic material was probably RNA, not DNA RNA molecules called ribozymes have been found to catalyze many different reaction - For example, ribozymes can make complementary copies of short stretches of RNA Vesicles with RNA capable of replication would have been protocells RNA could have provided the template for DNA, a more stable genetic material

8 Origin of Life RecAp https://www.youtube.com/watch?v=SWY3FKbtEz8


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