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Water: The “universal solvent”

Water: The “universal solvent”. “Hydration shell”. Figure 3.8 A water-soluble protein. Water can dissociate into it’s ions:. H2O H + + OH -. [55M]. [10 -7 M] [10 -7 M]. The Ion Product of water ([H + ] x [OH - ]) is always 10 -14 This is the basis for the pH scale.

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Water: The “universal solvent”

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  1. Water: The “universal solvent” “Hydration shell”

  2. Figure 3.8 A water-soluble protein

  3. Water can dissociate into it’s ions: H2OH+ + OH- [55M] [10-7M] [10-7M] The Ion Product of water ([H+] x [OH-]) is always 10-14 This is the basis for the pH scale.

  4. Definitions: Acid: A substance that increases the [H+] in aqueous solution. Ex. HCl H+ + Cl- (strong acid) H2CO3 H+ + HCO3- (weak acid) Base: A substance that reduces the [H+] in aqueous solution. Ex. NaOH Na+ + OH- (strong base) NH3 + H+ NH4+ (Weak base)

  5. Remember, that the Ion Product in water is always 10-14 Ex. If HCl is added to water to make 1M HCl HCl [H+] + [Cl-] 1M 1M Ion product = 10-14 = 1M x [OH-], [OH-] = 10-14M Or, if NaOH were added to bring the [OH-] to say 10-3M, then the [H+] would be 10-11M (10-3M x 10-11M = 10-14M) The pH scale was invented to simplify the expression of these concentrations. pH = -log [H+] Ex. If [H+] = 10-7, pH = -log 10-7 = 7

  6. Figure 3.9 The pH of some aqueous solutions

  7. Food we ingest and metabolic products in our cells can be acidic or basic, so how is pH controlled in our bodies?

  8. BUFFERS! Buffers: Substances that accept or donate H+ in solution stabilizing the pH. Weak acids and weak bases can act as buffers: Ex. H2CO3 HCO3- + H+ Response to rise in pH Response to drop in pH (increase in H+) If buffering capacity is overwhelmed, and physiological pH is altered, it can mean death to an organism.

  9. Sulfur oxides and nitrogen oxides and CO2 dissolve in water to form acids - acid precipitation. Freshwater and Ocean Acidification

  10. CARBON AND THE MOLECULAR DIVERSITY OF LIFE The molecules that make up organisms are carbon based compounds. Organic molecules - carbon-containing. CH4, other hydrocarbons, Carbohydrates, Lipids, Proteins and Nucleic Acids (DNA) are all organic molecules. Why Carbon? -Carbon is extremely versitile, its electron configuration allows it to form many different types of bonds, to form many different types of molecules.

  11. Carbon (valence 4) can form bonds with itself and the other elements common in living organisms; H, O, N - 4 single bonds (sp3) -1 double bond and 2 single bonds -1 triple bond and 1 single bond

  12. Figure 4.2 The shapes of three simple organic molecules

  13. Figure 4.4 Variations in carbon skeletons

  14. Figure 4.4x Hydrocarbons: molecular models Butane Isobutane Hexane Note that all carbons have tetrahedral arrangement Cyclohexane

  15. Functional Groups attached to carbon backbones produces structural and functional diversity Sugars, amino acids, lipids Sugars Sugars, lipids Amino acids, proteins, fatty acids Amino acids, proteins, neurotransmitters Amino acids, protein (structure) DNA, RNA, energy carrier molecules, some protiens

  16. Slight change in functional groups can result in major functional changes in organic molecules. Testosterone (male sex hormone) Estradiol (female sex hormone)

  17. More variation in organic molecules comes from different spatial arrangement - Isomers Cis and Trans isomers Mirror image molecules

  18. Figure 4.7 The pharmacological importance of enantiomers

  19. STRUCTURE AND FUNCTION OF MACROMOLECULES Biological molecules, carbohydrates, Lipids, proteins and nucleic acids are extremely large - Macromolecules Carbohydrates (some), proteins and nucleic acids are chain-like molecules called polymers. Polymers are made by covalently linking together subunits called monomers. While the monomer subunits differ for different classes of macromolecule, the mechanism used in cells to make and break polymers is basically universal.

  20. CARBOHYDRATES Include sugars and polymers of sugars- Fuel and structural components of cells. Molecular formula: CH2O ex. Glucose C6H12O6 Sugars have 3 or more carbons, a carbonyl group (C=O) and multiple hydroxyl groups (OH).

  21. Figure 5.3 The structure and classification of some monosaccharides Aldehydes Ketones

  22. Figure 5.4 Linear and ring forms of glucose Monosaccharides are utilized by cells for energy.

  23. When glucose forms a ring structure, the OH on C1 can be up (b) or down (a). 64% 36%

  24. Two sugars monosaccharides linked together are disaccharides. Figure 5.5 Examples of disaccharide synthesis a a Lactose (milk sugar) is a disaccharide of glucose and galactose.

  25. Polysaccharides are macromolecules with storage and structural functions. Figure 5.6 Storage polysaccharides

  26. Comparison of a storage and a structural polysaccharide. Figure 5.7b,c Starch and cellulose structures 

  27. Figure 5.8 The arrangement of cellulose in plant cell walls

  28. Figure 5.9 Chitin, a structural polysaccharide: exoskeleton and surgical thread NH amide C = O CH3

  29. Figure 5.2 The synthesis and breakdown of polymers Dehydration synthesis or Condensation reaction Hydrolysis

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