BIO1130 midterm 1 notes - Hadean & Archean Eons

BIO1130 midterm 1 notes - Hadean & Archean Eons -...

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Hadean and Archean Eons Geological Time Scale (Major Eons): Hadean and Archean (this unit) Hadean (4,600 – 3,800 Ma) - Formation of solar system and planet, ends off with origin of life Archaean (3,800 – 2,500 Ma) - Anaerobic bacterial life, oxygen starts to accumulate in atmosphere (Archea – live in extreme conditions) Proterozoic (2,500 – 543 Ma) - Oxygen atmosphere, single celled aerobic organisms Phanerozoic (543 Ma to Present) - Multicellular organisms Hadean Eon: Building Phase: - Meteorites that contained lots of minerals (C, H, O) crashed into Earth’s surface and provided it with the basic building blocks of life. - At this point, Earth is still a molten ball and meteorites are still flying into it on a regular basis Stabalizing Phase: - Earth starts to develop a crust on top of the molten lava - Earth is unique in which its mass is able to hold in an atmosphere so it could trap in the molecules needed to survive - The water vapour in the air starts to cool down and water starts to accumulate on the Earth’s surface which formed the oceans. - However, if another meteorite strikes then the water is Vapourized ( Evaporation ) because of the intense amount of heat created by the impact and the cycle starts over again. - Meteorites stopped hitting the Earth at the end of Hadean Eon Panspermia: - Life came from extraterrestrial origins. - No conclusive arguments (bacteria came from meteorites to Earth) - We still don’t know WHERE exactly life came from - Hypothesis that proposes life on Earth was transferred from elsewhere in the Universe Carbon: - All life on earth is carbon – based. (Silicon has the same properties as carbon and somewhere in the universe there might be a whole parallel forms of life all based on silicon instead of carbon – Silicon used in computer chips here on Earth) - Carbon is the ideal “lego block” for building larger structures (organisms). This is because carbon is a perfectly symmetrical element (tetrahedral orientation of its electrons). Adhesion: - Water sticks to other objects - The adherence of molecules to the walls of conducting tubes, as in plants - Explains the meniscus you see in test tubes, etc. Cohesion: - The high resistance of water molecules to separation. - Water has a high tendancy to stick together due to polar characteristics - Surface tension is an example of cohesion Surface Tension:
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Hadean and Archean Eons - The force that places water molecules under tension, making them harder to separate than the water molecules under them. At the top, water molecules are in contact with air, so surface tension is created. - Some insects are able to walk on water due to surface tension. (Due to cohesion) - Surfactants: o Reduce the surface tension of water by absorbing at the liquid-gas interface o Can also form micelles and vesicles in water. When micelles form, polar phosphate heads stick out towards water, and tails form a core that can encapsulate an oil droplet. Non-Polar Compound:
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This note was uploaded on 01/17/2010 for the course BIO BIO1130 taught by Professor Houseman during the Fall '09 term at University of Novi Sad.

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BIO1130 midterm 1 notes - Hadean & Archean Eons -...

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