+ Chapter 14 Section 2

Activity - Earth’s timeline Materials: 1 ruler, 1 sheet of paper, colored pencils or markers Instructions: Draw a horizontal line that will represent the timeline of Earth’s History The far left side starts at the current estimated formation of the Earth, mark 4.6 Billion Years ago The far right side represents present day Place these key events where your group estimates they happened and include a date, ex 2.6Bya, 100Mya, 14,000 yrs Work in groups of 4 Do not talk to other groups 1. 1 st flowering plants 2. 1 st Life 3. Multicellular organisms 4. Invasion of Land 5. 1 st Eukaryotes 6. 1 st Photosynthetic bacteria 7. Extinction of Dinosaurs 8. Last of the Glaciers recede from temperate zones 9. Homo Sapiens appeared 10. Continents appear essentially as they do today st Aerobic Bacteria

4.6 Bya Formation of Earth 3 Bya 1 st Photosynthetic bacteria 4By a 3By a 2By a 1By a 3.8 Bya 1 st Life 800 Mya Multicellular Organisms 300 Mya Invasion of land 250 Mya 1 st flowering Plants 65 Mya Extinction of Dinos 20 Mya Continents appear as they do today 160,000 yrs Homo sapiens 15,000 Yrs Last Glaciers Recede 2.1 Bya 1 st Aerobic Bacteria 1.6 Bya 1 st Eukaryotes

+ Warm up question 1. What does the 1 st flask contain? 2.How does the broth change during the experiment? -use complete sentences Broth is boiled 1 yr passes, broth remains clear Curved neck is removed One day passes, broth becomes cloudy

+ The Formation of Earth Our solar system began as a swirling mass of gas and dust 5 Billion years ago Most material was pulled together by gravity and formed the sun Planets formed through repeated collisions of space debris Earth formed to roughly it’s size today over a 400 Million year period

+ How did the Oceans form? 4 billion years ago, the Earth could be described as a very large, hot rock without a trace of water on its surface As the Earth cooled to below 100 o C oceans were formed when water vapor condensed and formed liquid water. Water on the young Earth came from two sources Outgassing from within the Earth process whereby gases are released from molten rock in the mantle of the planet by volcanic activity Bombardment by comets

+ First Organic Compounds All elements found in organic compounds existed on Earth when it was formed but how were they assembled into compounds? Early atmosphere contained: Ammonia NH 3 Hydrogen gas H 2 Water vapor H 2 O Hydrocarbons CH 4

+ Alexander I. Oparin and John Haldane – 1920’s Oparin hypothesized that at high temperatures these formed simple organic compounds  Amino acids Energy supplied by lightning and U.V. rays These ultimately resulted in macromolecules essential for life How did elements form into the 1 st organic compounds?

+ The Miller-Urey experiment 1. A solution of simple chemicals is heated producing an “atmosphere” 2. Electrical sparks simulate lightning, provides energy for synthesis of new compounds 3. A condenser cools atmospheric gases, collect in “ocean” 4. Condensate is analyzed Stanley L. Miller ( ) Harold Urey (1893 – 1981) Hypothesis: Organic chemical compounds can be generated under conditions similar to those that existed on primitive Earth Conclusion: The chemical building blocks of life (amino acids, ATP, nucleotides) could have been generated in the atmosphere of early Earth

+ Molecules to cell like structures In solutions of simple organic chemicals cell-like structures will spontaneously form Microspheres – spherical, composed of many proteins. Mimic a cell membrane Coacervates – collections of droplets that are composed of molecules of different types. Amino acids, lipids, and sugars

+ Cell Like properties (coacervates/microspheres) Ability to take up substances from their surroundings Growth Budding to form smaller structures NO HERHEREDITARY CHARATORISTICS