BIOL 1407 Lecture Notes - Lecture 2: Quaternary Extinction Event, Radiometric Dating, Gram Staining
Document Summary
History of life on earth chapter 25. How it forms: specimen buried in sand/mud, organism degrades. Biases of fossil formation: tend to fossilize in wet environments, works best with bones/hard surfaces/wood. Helps scientists see what was alive in many places in the world at a given time. When did the earth form: 4. 6 billion years ago. What was earth like until about 3. 9 bya: earth was too hot to form life, no oxygen, no water, hydrogen gas, helium gas (cid:0) toxic gases. Earth"s surface primordial soup: water and dissolved atoms collected on. Macromolecules: form naturally through polymerization naturally forming small organic molecules: energy efficient. Protobionts (microspheres): first living cell: naturally form a semi-permeable membrane. Operating instructions: rna: first genetic information to form. Can work as an enzyme: dna. Dna replaced rna as the primary source of genetic information. Heterotrophs: have to eat can"t make own food.
