History of Life on Earth - Application of Biology - Lecture Slides, Slides of Biology

Download History of Life on Earth - Application of Biology - Lecture Slides and more Slides Biology in PDF only on Docsity! Docsity.com  Earth is about 4.6 billion years old  Very HOT  Atmosphere did not contain oxygen  Atmosphere contained gases toxic to life as we know it:  Hydrogen cyanide  Carbon monoxide  Hydrogen sulfide Docsity.com  How DNA evolved is still unknown  One theory says that RNA evolved first (it can replicate on its own)  Maybe RNA produced the first DNA and that led to the DNA-directed protein synthesis of cells today Docsity.com RNA and DNA Cytosine RNA Nitrogenous " g se Nitrogenous Bases Ribonucleic acid Deoxyribonucleic acid Bases  First prokaryotic cells must have been able to survive without oxygen  Prokaryotic cells evolved the ability to carry out photosynthesis, thus producing oxygen  Other life forms that use oxygen could then evolve, other forms of life were driven extinct by the change in the atmosphere Docsity.com  Single cells could live together as a colony  If this provided an advantage, it would be selected  Led to multicellular organisms Docsity.com  Few fossils exist because the majority of animals were soft-bodied. Docsity.com Docsity.com Docsity.com  Carboniferous/Permian  Reptiles evolved from amphibians (scales and leathery egg shells)  Winged insects  Giant ferns and other plants form forrests  Coal deposits  Mass extinction  95% of organisms  Did not affect many fish or reptiles Docsity.com  Triassic Period  Reptiles very important  Cone-bearing plants  First dinosaurs  First mammals (mouse or shrew)  Jurassic Period  Dinosaurs ruled the land  First bird appeared  Cretaceous Period  Flowering plants  Mass extinction (50% of species) Docsity.com