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Life’s Origin and Early Evolution. Chapter 20. 20.1 In the Beginning. Knowledge of modern ___________________ and ___________________ are the basis for scientific ___________________ about early events in Earth’s history. Ongoing Star Formation.
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Life’s Origin and Early Evolution Chapter 20
20.1 In the Beginning . . . • Knowledge of modern ___________________ and ___________________ are the basis for scientific ___________________ about early events in Earth’s history
Ongoing Star Formation • The Eagle ______________, photographed by the Hubble space telescope
20.2 How Did Cells Emerge? • We will never know for sure how the first ___________________ came to be, but we can investigate the possible steps on the road to ___________________
Possible Origins of Complex Organic Compounds • Clay templates on _________________ flats; iron-sulfide rocks at hydrothermal vents on the ___________________ floor
Models for Protocells • _______________________________ vesicles and ___________________ -coated clay
living cells membrane-bound proto cells self-replicating system enclosed in a selectively permeable, protective lipid sphere enzymes and other proteins DNA RNA formation of protein–RNA systems, evolution of DNA formation of lipid spheres spontaneous formation of lipids, carbohydrates, amino acids, proteins, nucleotides under abiotic conditions Fig. 20-6c, p. 321
The Rise of Eukaryotes • Oldest eukaryotic fossils: __________________ years
Origins of Nucleus, ER, and Golgi Body • The ___________________ and ____________ may have arisen through modification of infoldings of ___________________
Lessons of Chile’s Atacama Desert • What we learn about life on Earth informs our ideas about the possibility of life ___________________