BIOL 1202 Chapter : Chapter 25 Outline
Document Summary
Chapter 25: the history of life on earth. Concept 25. 1: conditions on early earth made the origin of life possible. Scientists hypothesize that chemical and physical processes on early earth, aided by the emerging force of natural selection, could have produced very simple cells through a sequence of four main stages: 1. ) The abiotic (nonliving) synthesis of small organic molecules, such as amino acids and nitrogenous bases: 2. ) The joining of these small molecules into macromolecules, such as proteins and nucleic acids: 3. ) The packaging of these molecules into protocells - droplets with membranes that maintained an internal chemistry different from that of their surroundings: 4. ) The origin of self-replicating molecules that eventually made inheritance possible. There is evidence that earth and the other planets of the solar system formed about 4. 6 million years ago, condensing a vast cloud of dust and rocks that surrounded the young sun.
