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Origin of Life

Explore the fascinating topic of Earth's origins and the various hypotheses proposed for the emergence of life. From the nebula hypothesis to the role of organic molecules and early cell structures, this chapter delves into the complexity of life's evolution. Discover how microbes, fossils, and endosymbiosis shaped the planet, leading to the diversification of species and the move onto land.

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Origin of Life

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  1. Origin of Life Biology Chapter 12

  2. Earth was very different billions of years ago. • There have been many hypotheses of Earth’s origins. • The most widely accepted hypothesis of Earth’s origins is the nebula hypothesis.

  3. View Cosmic Collisons

  4. electrodes “atmosphere” water “ocean” heat source amino acids Several sets of hypotheses propose how life began on Earth. • There are two organic molecule hypotheses. • Miller-Urey experiment • meteorite hypothesis

  5. iron-sulfide bubbles hypothesis • There are different hypotheses of early cell structure.

  6. lipid membrane hypothesis • There are different hypotheses of early cell structure.

  7. A hypothesis proposes that RNA was the first genetic material. • Ribozymes are RNA molecules that catalyze their own replication. • DNA needs enzymes to replicate itself.

  8. Microbes have changed the physical and chemical composition of Earth. • The oldest known fossils are a group of marine cyanobacteria. • prokaryotic cells • added oxygen toatmosphere • deposited minerals

  9. Fossil stromatolites provide evidence of early colonies of life.

  10. Eukaryotic cells may have evolved through endosymbiosis. • Endosymbiosis is a relationship in which one organism lives within the body of another. • Mitochondria and chloroplasts may have developed through endosymbiosis.

  11. View interactive from text book • Endosymbiosis clip

  12. The evolution of sexual reproduction led to increased diversity. • Genetic variation is an advantage of sexual reproduction. • Sexual reproduction may have led to the evolution of multicellular life.

  13. Life moved onto land during the Paleozoic Era. • Multicellular organisms first appeared during the Paleozoic era. • The era began 544 million years ago and ended 248 million years ago. • The Cambrian explosion led to a huge diversity of animal species.

  14. Life moved onto land in the middle of the Paleozoic era.

  15. Reptiles radiated during the Mesozoic era. • The Mesozoic era is known as the Age of Reptiles. • It began 248 million years ago and ended 65 million years ago. • Dinosaurs, birds, flowering plants, and first mammals appeared.

  16. Mammals radiated during the Cenozoic era. • The Cenozoic era began 65 million years ago and continues today. • Placental mammals and monotremes evolved and diversified. • Anatomically modern humans appeared late in the era.

  17. View Biology book flim clip

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