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The Chemistry of Life

The Chemistry of Life. Why are we studying chemistry?. Chemistry is the foundation of Biology. The World of Elements. H. C. N. O. Na. Mg. P. S. K. Ca. Different kinds of atoms = elements. Hydrogen 1 proton 1 electron . Oxygen 8 protons 8 neutrons 8 electrons. Proton. +.

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The Chemistry of Life

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  1. The Chemistry of Life

  2. Why are we studying chemistry? Chemistry is the foundation of Biology

  3. The World of Elements H C N O Na Mg P S K Ca Different kinds of atoms = elements

  4. Hydrogen 1 proton 1 electron Oxygen 8 protons 8 neutrons 8 electrons Proton + Neutron 0 Electron –

  5. Why are we studying water? All life occurs in water • inside & outside the cell

  6. Chemistry of water • H2O molecules form H-bonds with each other • +H attracted to –O • creates a sticky molecule

  7. Cohesion & Adhesion • Cohesion • H bonding between H2O molecules • water is “sticky” • surface tension • Adhesion • H bonding between H2O & other substances • meniscus • water climbs uppaper towel or cloth

  8. How does H2O get to top of trees? Transpiration is built on cohesion & adhesion

  9. Water is the solvent of life • Polarity makes H2O a good solvent

  10. What dissolves in water? • Hydrophilic • substances have attraction to H2O

  11. What doesn’t dissolve in water? • Hydrophobic • substances that don’t have an attraction to H2O fat (triglycerol)

  12. The special case of ice • Most (all?) substances are more dense when they are solid, but not water… • Ice floats!

  13. Evaporative cooling • As water vaporizes from a surface it cools the temperature of that surface • sweating • panting

  14. Ionization of water & pH • Water ionizes • H+ splits off from H2O, leaving OH– • if [H+]= [-OH], water is neutral • if [H+]> [-OH], water is acidic • if [H+]< [-OH],water is basic • pH scale • how acid or basic solution is • 1  7  14 H2O  H+ + OH–

  15. Examples of Solutions pH pH Scale 0 Hydrochloric acid 1 2 Stomach acid, Lemon juice Vinegar, cola, beer 3 Tomatoes 4 5 Black coffee, Rainwater 6 Urine, Saliva 7 Pure water, Blood Seawater 8 Baking soda 9 Great Salt Lake 10 Household ammonia 11 12 Household bleach 13 Oven cleaner 14 Sodium hydroxide

  16. Buffers & cellular regulation • pH of cells must be kept ~7 • pH affects shape of molecules • shape of molecules affect function • pH affects cellular function • Control pH by buffers • reservoir of H+ • donate H+ when [H+] falls • absorb H+ when [H+] rises

  17. pH • A substance where H+ > OH- is a(n) _______. • A substance where H+ < OH- is a(n)_______. • What characteristic of life describes why it is important to maintain a “steady state” pH? • What substance helps to regulate pH in cells?

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