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
Early Earth
Stanley Miller’s Experiments
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
Fig. 20-6c, p. 321
membrane-bound proto cellsliving cells
self-replicating system enclosed in a selectively permeable, protective lipid sphere
DNA RNAenzymes and other proteins
formation of protein–RNA systems,
evolution of DNA
formation of lipid spheres
spontaneous formation of lipids, carbohydrates, amino acids, proteins, nucleotides under abiotic conditions
Fossil Prokaryotic Cells
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 ___________________
Evidence of Endosymbiosis
20.5 Time Line for Life’s Origin and Evolution
Lessons of Chile’s Atacama Desert
What we learn about life on Earth informs our ideas about the possibility of life ___________________
Major Events in the History of Life