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