| | Continuing the discussion started on Wednesday, we examine some of probable steps in the origin of life on earth. |
| | Life probably originated around 3.8 billion years ago. |
| | The conditions on the earth were suitable for building life. |
| | The building blocks of life were generated either by aboitic synthesis or arrived from extraterrestrial sources. |
| | These building blocks were used to generate the protiens, nucleic acids, and organic phosphates necessary for life. |
| | Life, once established, would change the environment so that life could not arise again. |
| | Setting the stage, 3.8 Billion years ago |
| | The earths atmosphere is rich in CO2, H2O, N2, lesser amounts of methane and amonia |
| | Temperature at the earths surface drops below 100 C |
| | Acidic rains fall, Erosion begins |
| | UltraViolet light beats down |
| | The earth's crust is thin and hot |
| | Warm mineral-rich oceans form |
| | The Building blocks of life |
| | nucleic acid bases, sugars, phosphoric acid |
| | The origins of the building blocks |
| | Concentrating the building blocks |
| | nucleic acids bases, sugar, phosphoric acid to nucleic acids (DNA, RNA) |
| | Catalyzed reactions on clay minerals |
| | amino acids and nucleic acid bases are attracted and bind to clay minerals |
| | Combining the building blocks into a self-replicating cell |
| | enclosing an environment of proteins, DNA, RNA, ATP and their building blocks. |
| | Once life was established it would consume the organic building blocks. |
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