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Chemical Basis of Life

Chemical Basis of Life. Ionic Bonding. http://www.es.ucsc.edu/~es10/classnotes/lectures/ionic.bond.jpg. Covalent Bonding. http://www.gcsescience.com/Methane-Molecule.gif. http://media-2.web.britannica.com/eb-media/04/96904-004-C880B85D.gif. Hydrogen Bonding.

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Chemical Basis of Life

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  1. Chemical Basis of Life

  2. Ionic Bonding http://www.es.ucsc.edu/~es10/classnotes/lectures/ionic.bond.jpg

  3. Covalent Bonding http://www.gcsescience.com/Methane-Molecule.gif http://media-2.web.britannica.com/eb-media/04/96904-004-C880B85D.gif

  4. Hydrogen Bonding http://upload.wikimedia.org/wikipedia/commons/f/f9/3D_model_hydrogen_bonds_in_water.jpg http://schools-wikipedia.org/images/646/64609.png

  5. Properties of Water 1. Strong Polarity: • Polar water molecules attract other polar compounds causing them to dissociate • Water is a great solvent • Many molecules can dissolve in cells (mostly water) • Allows for chemical reactions and transportation

  6. Properties of Water 2. High Specific Heat • Hydrogen bonds absorb heat when broken and release heat when formed • This minimizes temperature changes in the body • Body temp remain relatively constant • High Heat of Vaporization • Energy needed to break H+ bonds • Body can dissipate excess heat & maintain a normal body temperature by evaporation

  7. Properties of Water • Cohesion • Water molecules provide lubrication or cushioning to protect against damage from friction or trauma

  8. Electrolytes Substances that dissociate (break up) in solution to form charged particles or ions. • Examples: Acids, bases, salts • Cations: positive charged ions • Anions: negative charged ions

  9. Acids & Bases Acid – any substance that releases H+ when in solution • “proton donor” • Ex: HCl (stomach acid) Base – any substance that increases the OH- concentration when dissociated in solution • “proton acceptor” • “Ex: NaOH

  10. pH Scale Represents the H+ ion concentration in a solution 7 = neutral 0-6 = acidic 8-14 = basic/alkaline

  11. Buffers Any molecule that moderates changes in pH. • Key role in the body’s ability to maintain a normal pH (homeostasis) Many buffers are anions that have a strong affinity for H+ • bicarbonate ion (HCO3-) is an important buffer in the human body

  12. Carbohydrates Building Block – Monosacchride Disaccharides – 2 monosacchrides covalently bonded Polysaccharides – complex carbohydrates

  13. Carbohydrates • Structure: • Contains the elements C, H, O • H and O always in 2:1 ratio • Monosaccharides form short carbon chain • Ex: Glucose (C6H12O6) • Function: • Provide energy for cellular activities • Structural support in DNA (deoxyribose) and RNA (ribose)

  14. Lipids Includes: fats, phospholipids, steroids and prostaglandins • Water insoluble • Fats/Triglycerides: • Structure: glycerol & 3 fatty acid tails • Function: concentrated energy source http://www.future-of-technology.com/web_images/triglyceride.jpg

  15. Lipids cont…. • Phospholipids • Structure: glycerol, 2 fatty acid tails & a phosphate group • Head: water soluble (“hydrophilic”) • Tails: fat soluble (“hydrophobic”) • Function: main component of cell membrane http://www.fz-juelich.de/isb/isb-1/datapool/page/28/Figure1-500.jpg

  16. Lipids cont…. • Steroids • Cholesterol: Provides stabilization function in cell membrane • Other examples: estrogen & testosterone 4. Prostaglandins

  17. Proteins • Wide range of functions: • Defense system (antibodies) • Serve as receptors or binding sites • Structural (skin, tendons, nails) • Catalyze chemical reactions (enzymes) • Communication (insulin – protein hormone)

  18. Amino Acids Building blocks of proteins • 20 amino acids • 8 are essential (must be obtained through diet) • Structure: • Amine group • Carboxyl group • Side chain (determines unique properties of amino acid) http://www.aloeveraibs.com/wp-content/uploads/2008/08/aminoacidstruc.jpg

  19. Enzymes • Largest group of proteins in the body. • Chemical catalyst • Assist in chemical reactions but are not products nor reactants • Not changed by the reaction • Usually end in -ase

  20. Nucleic Acids • Form genes and take part in protein synthesis • Building block – nucleotide • Phosphate • Nitrogen Base (Adenine, Guanine, Cytosine, Thymine) • 5-carbon sugar (deoxyribose in DNA) • Ex: DNA, RNA http://bbruner.org/bitn/bitn_fig/dna.gif

  21. Metabolism All the chemical reactions that take place in our body’s cells. • Catabolism: Chemical reaction that breaks down large molecules into smaller units. This type of reaction releases energy. Also called a hydrolysis reaction because a water molecule is added for the reaction to occur. • Anabolism: Chemical reaction that combines smaller molecules to form larger molecules. This type of reaction requires energy, usually ATP. Also called a dehydration synthesis reaction because a water molecule is removed during the reaction. • Fig 2-25, p. 61

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