CHEM 110 - Biology 111 Lecture 1: - Bios (life) + logos...

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Biology 111 Lecture 1: - Bios (life) + logos (reason) Lecture 2: Origin and Evolution of Life: Life here 85% of time, vertebrates 12%, on land 9%, humanoids 0.1% Ancient History: 14 bya= Big Bang 5 bya = Our Sun born 4.5 bya= Earth formed 3.8 bya= First cells/life 2 bya= Eukaryotes 1 bya= Multicellular life 0.54 bya= Cambrian Explosion (all modern phyla) 0.42 bya= Life marches onto land 0.006 bya= Humans - 1.8 bya by prokaryotes only, 2.8 bya by single celled only, 3.1 bya by by much simpler than modern life Life is old- life as we know it is relatively young- humans are basically irrelevant! A recipe for life: 1) Ancient (pre-oxygen) atmosphere zapped with lightning- amino acids, sugars, nucleic acids, lipids (Urey-Miller 1950’s) 2) Building blocks placed in several contexts- polymers (long chains=proteins, starches, RNA/DNA) 3) RNA uniquely positioned- a template for copying itself, a catalyst for chemical reactions 4) Lipids naturally form bilayer spheres- swallow RNA and provide a more stable environment 5) Proteins more efficient catalysts than RNA- ribosomes (map RNA sequence to protein) Origin of Life- incremental small chance events Modern Life- Precambrian- largely unicellular (4500 mya) Paleozoic- old life (540 mya) Mesozoic- middle life (250 mya) (Pangaea) Cenozoic- new life (65 mya) (asteroid) Anthropocene- human age (0.01 mya) (glaciers retreat) Proterozoic Life- Stromatolites= layered cyanobacterial concretions Eobacterium- 3100 mya Fossil- 2000 mya Late Proterozoic- the eukaryotes
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About 800 mya, larger organisms began to appear in the fossil record. Among these are the first eukaryotes. From about 610 mya there are abundant remains of a characteristic fauna composed of enigmatic organisms that flourished worldwide before becoming extinct near the base of the Cambrian period, 540 mya. Ediacaran Fossils- named for an Australian locality, were first found in Canada. Paleozoic Era (540 mya - 250 mya)- - Begins with Cambrian Explosion- relatively rapid (few million years) appearance of all modern phyla (including arthropods, vertebrates, etc) - Early Fauna (trilobites) -> late fauna (corals, nautiloids, crinoids=sea fans) - March onto land in the middle (plants, insects, vertebrates all about the same time 420 mya) - Coral forests- lycopods and horsetail trees (+ferns) with giant amphibians, dragonflies, and the beginnings of reptiles. - End with continents colliding to form Pangaea at 250 mya- collision causes massive vulcanism and mass extinction. Burgess Shale- British Columbia, Canada -The earliest metazoan fauna diversified in the Cambrian period at the beginning of the Paleozoic, about 530 mya. Life on land in Mid-Paleozoic- The earliest land plants evolved in the Devonian period, in the middle of the Paleozoic about 400 mya.
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CHEM 110 - Biology 111 Lecture 1: - Bios (life) + logos...

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