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Origins of life F2018 cee
- 1. The Origin and History of Life Unit 1 Meteorite: ©Joe Tucciarone/Science Source Copyright © McGraw-Hill Education. All rights reserved. No reproduction or distribution without the prior written consent of McGraw-Hill Education. Principles of Biology I - BIO 1407
- 3. Biology - the scientific study of life.
- 5. Learning Objectives Students will be able to: •Summarize the major events of life’s history on the geologic timescale. •Outline the scientific evidence for the origin of life on Earth. •Describe how conditions on the early Earth could contribute to the production of biological molecules.
- 6. Life’s Origin Remains Mysterious Section 15.1 Life arose on Earth about 4 billion years ago. Scientists know little about life’s origin or origins. Figure 15.1
- 8. Section 15.1 Figure 15.3 Life’s Origin Remains Mysterious
- 9. S. Miller & H. Urey Experiment - 1953
- 10. Section 15.1 The Miller experiment simulated early Earth’s atmosphere. Simple molecules combined into organic compounds, such as amino acids. Figure 15.4 Life’s Origin Remains Mysterious
- 12. Figure 15.5 Life’s Origin Remains Mysterious • Clay and iron pyrite likely catalyzed the first synthesis reactions. • Once a self-replicating molecule—like RNA— formed and replicated, natural selection took over. Stable molecules that could self-replicate became more common.
- 13. 15_page309 Life’s Origin Remains Mysterious • Lipid membranes might have enclosed some self-replicating systems, forming the first protocells. • Protocells eventually gave rise to the first life—prokaryotes.
- 14. Section 15.1 The first cells lived without oxygen. Early Life Changed Earth Figure 15.6
- 15. Endosymbiosis:
- 16. Section 15.1 Eventually, organisms evolved that used H2O during photosynthesis, producing O2 as a byproduct. Early Life Changed Earth Figure 15.6
- 17. The Great Oxygenation Event
- 19. TopHat Question #1 Why was the Miller experiment important? A. It showed life could be created in a test tube. B. It demonstrated how the first cells arose on Earth. C. It showed that RNA was the first self- replicating molecule. D. It demonstrated Earth’s early atmosphere could have given rise to organic molecules. E. All of the choices are correct. Flower: © Doug Sherman/Geofile/RF
Editor's Notes
- This is (obviously) a biology class. So let’s start by defining what Biology is….they have probably been giving the “Biology is the study of life” definition before….ask “Why do you think we added the word “scientific” to the definition? How does a “scientific” study differ from just a “study”? These stromatalites are evidence of the ancient microbes that were the only form of life for 85% of the history of life on Earth before more complex life evolved. Photo from Shark Bay, in Western Australia, which is a UNESCO World Heritage Site. Image courtesy NASA. http://www.isgtw.org/feature/cern-lends-hand-origin-life
- For this unit we will begin with an explanation of the origin of Earth’s biodiversity. Then discusses how the hierarchical levels of life likely formed to produce the first living organisms. Evidence for the origins of organic molecules will be provided with an explanation of the Miller’s prebiotic experiment. Miller’s experiment showed how a chemical “soup” could form many of the molecules making up living organisms. Other models of organic evolution are also presented to support Miller’s work.
- COMMON STUDENT MISCONCEPTIONS There is ample evidence in the educational literature that student misconceptions of information will inhibit the learning of concepts related to the misinformation. The following concepts covered in this presentation are commonly the subject of student misconceptions. This information on “bioliteracy” was collected from faculty and the science education literature. Students believe that all evolutionary changes are gradual. Students believe that organic evolution could not have taken place on Earth. Students believe that the origins of life started out as random atoms coming together to form molecules. Students believe that the early oceans were salty. Students believe that the early atmosphere contained oxygen.
- When covering the Miller experiment, it is important to stress that the conditions on the primordial Earth were significantly different from those that exist today and that one of the most important life-sustaining characteristics, free oxygen gas, is a by-product of the metabolism of primitive living organisms. Have students consider the likelihood of life continuing as it is with anthropogenic environment changes such as upper atmosphere ozone depletion and global climate change.
- We will talk about prokaryotes in detail in the next unit.