Origin of Life PDF
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This document discusses the various theories surrounding the origin of life on Earth, examining creationism, spontaneous generation, panspermia, and the Oparin-Haldane theory. It also details the Miller-Urey experiment, a crucial step in understanding the development of organic molecules. The document explores the concept of LUCA, the Last Universal Common Ancestor, and the challenges in understanding the single origin of life.
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HOW DID LIFE ORIGINATE ON EARTH ? Module 5. Where does everything come from? When and how did life begin? How did life originate on Earth? FIRST THEORIES OF THE ORIGIN OF LIFE We have two initial theories: 1. Creationism 2. Spontaneous Generation...
HOW DID LIFE ORIGINATE ON EARTH ? Module 5. Where does everything come from? When and how did life begin? How did life originate on Earth? FIRST THEORIES OF THE ORIGIN OF LIFE We have two initial theories: 1. Creationism 2. Spontaneous Generation Most cultures explained the origin of life thorugh a divine intervention. Examples: Mayan mythology: Tepeu and Gucumatz CREATIONISM Egyptian mythology: Ra Life emerged out of nowhere. Examples: Shakespeare’s play: crocodiles emerged from mud and heat of the sun. SPONTANEOUS Dutch Dr. Johan B. van Helmont (1667): Bugs, ticks, fleas, and worms are GENERATION our parasites and are born from our bowels and excrement. REDI AND SPONTANEOUS VS. PASTEUR GENERATION Experiment by Francesco Redi Proved maggots come from flies REDI AND SPONTANEOUS VS. PASTEUR GENERATION Experiment by french scientist Louis Pasteur Last blow against spontaneous generation Life can’t be spontaneusly generated, but how did life appear for the first time? THEORY OF PANSPERMIA Panspermia, greek Pan -> all Sperma -> seed August Arrhenius (swedish scientist, 1908): Life appear from a bacteria or spore from outer space. THEORY OF PANSPERMIA Arguments against: Outer space is not suitable for life Doesn’t explain origin of life OPARIN-HALDANE THEORY Alexander Oparin J.B.S. Haldane Soviet biochemist British geneticist In 1921... In 1920... Both scientist published the same hypothesis: In the primitive Earth, the biomolecules of life could be formed. OPARIN-HALDANE THEORY In the primitive Earth, the biomolecules of life could be formed. Primitive earth was Gases: different: Methane Energy Formation of Ammonia Atmosphere lacked Water vapor complex biomolecules from free oxygen but had UV radiation Carbon simpler molecules Cosmic rays dioxide other gases SIMULATING THE PRIMITIVE EARTH Miller-Urey experiment in 1952 by chemists Stanley Miller and Harold Urey. THEORY OF ABIOGENESIS OR CHEMICAL EVOLUTION Results of the Miller-Urey experiment provided evidence that organic molecules arise from simple inorganic precursors under conditions similar to those proposed by the Oparin-Haldane hypothesis. This lent support to the idea that life could have originated through natural chemical processes on the early Earth. AND THEN WHAT HAPPENED? We have biomolecules from the Miller-Urey experiment but some 1..Chemical Evolution other events are needed to have 2. RNA World Hypothesis the first life form. 3. Primitive Metabolism Mexican biologist Antonio Lazcano Araujo proposed in 1952 4. The first membranes the following events: LUCA: LAST UNIVERSAL COMMON ANCESTOR LUCA: first live form is the ancestor of every living organism in Earth and we don’t know how it looked. Why was there only one origin of life? We don't know for certain. But we know that it could only happen in the conditions of primate Earth. And after the appearance of life, Earth has changed too much.
