Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
ORIGINS OF HEREDITY Pages 287-290 FIRST GENETIC MATERIAL •RNA is thought to have been the first heredity molecule •Evidence: •Can make many shapes •Some RNA, called ribozymes, can replicate themselves •Quite a few viruses use RNA instead of DNA such as Ebola and measles FIRST GENETIC MATERIAL •It is hypothesized that this RNA started to evolve inside cell-like structures made of proteins, amino acids, and lipids •Then the RNA started to direct the cell THE FIRST CELLS •Prokaryotes came before eukaryotes •The first cells did not use oxygen (it was toxic to them), and depended on the organic molecules (primordial soup: think Oparin) in the environment for food •Later photosynthetic cells evolved and put oxygen into the atmosphere •Oxygen prevented further Spontaneous Generation THE FIRST CELLS •Order of major events in cell evolution • Anaerobic Aerobic • Heterotrophic Autotrophic • Chemosynthetic Photosynthetic • Don’t use oxygen use oxygen • Don’t make own food make own food •Energy comes from chemicals energy comes from sunlight THE FIRST EUKARYOTES THINK ABOUT IT What knowledge do we have about mitochondria and chloroplasts that provide evidence that they might have lived independently at one point? THE FIRST EUKARYOTES Endosymbiosis Theory •Mitochondria and chloroplasts are thought to have once been prokaryotic cells that were engulfed by a bigger prokaryotic cell •Supporting Evidence: •Both organelles contain their own DNA •DNA is circular (like other prokaryotes) •Replicate on their own