EH1008 Biomolecules Lecture 2: Inorganic and organic chemistry [email protected]1 Inorganic & Organic Chemistry • Inorganic Chemistry: generally, substances that do not contain carbon • Inorganic molecules: lack C and H chains Exceptions: CO, CO 2 , and HCO 3 - Often formed by ionic bonds, but not always e.g. H 2 O, O 2 , CO 2 , salts, acids, bases, calcium phosphate • Organic Chemistry: study of carbon-containing substances. Those that are biologically active are called biochemicals. • Organic molecules based on C and H chains structurally complex typically formed by covalent bonds e.g. sugars, amino acids, vitamins, etc. 2 Water • Cells need a continuous supply of nutrients, removal of waste products. • Living cells contain mostly water and GENERALLY interact with an aqueous environment: • blood plasma (e xtrac ellular f luid ): 92% water • 50% of female body weight and 60% of male •Water is the vital SOLVENT:- a (liquid) substance in which SOLUTES are dissolved. •inorganic salts (eg NaCl, KCl, nitrates, phosphates) •small organic molecules (eg sugars, amino acids) •dissolved gases (eg oxygen, carbon dioxide) 3
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Polarity allows it to serve as reactant in many reactions:
(i) Hydrolysis: decomposition using waterATP +H2O � ADP + Pi + energy
(ii) Dehydration synthesis: synthesis using waterADP + Pi � ATP + H2O
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4. Good solvent
•Water is considered as the universal solvent
•Polar and ionic substances dissociate easily in water to form solutions
•Solution: mixture of liquids, gasses, or solids that are uniformly distributed and chemically combined
Solvent: that which dissolves the soluteSolute: that which dissolves in the solvent
•Eg sweat is a salt solution: water is the solvent, salt (ionic substance) is the solute
•Water also dissolves certain organic substances e.g sugar and alcohols that do not dissociate into ions in solution but do have polar properties.
•Notewater does NOT dissolve or dissolve in compounds that are completely nonpolar eg. fats and oils
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Hydrophilic & Hydrophobic molecules•Compounds that dissolve in H2O are hydrophilic, those that
do not are hydrophobic
•Strict hydrophobic compounds do not mix well in H2O eg. lipids
•Some molecules have a hydrophobic and a hydrophilic end –amphipathic polar and non-polar end
•Amphipathic substances make good emulsifiers they can attract hydrophilic and hydrophobic molecules to them, eg sodium oleate/soap
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Properties of H2OWater also serves as a good mixing medium
Mixture : substances physically but NOT chemically combined
Solution: mixture of liquids, gases, or solids that are uniformly distributed and ARE chemically combined
Suspension: is a mixture of materials that separate unless stirred. Eg Sand and water, Blood - Plasma and red blood cells
Colloid: a mixture with properties between those of a solution and fine
suspension.
The dispersed (solute like) substance is distributed throughout a dispersing (solvent like) substance.
Proteins are dispersed particles Proteins +H2O = Colloids
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Solution Concentrations
• Concentration: measure of number of particles of solute per volume of solution
• Osmosis:movement of solvent along a concentration gradient across a semipermeable membrane. The cell membrane is semi-permeable.
• Osmole (Osm): moles of solute contribute to the osmotic pressure of a solution.
• Osmolality (Osm/kg): the amount (osmole/Osm) of particles dissolved in 1Kg of water
• Concentrations of particles in the human body: milliosmoles (mOsM)• 300 mOsMis average in the human body
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• Circulatory systemcarries water and solutes to capillaries, where exchange with cells occurs. Solutes must cross capillary wall, interstitial space and cell membrane to reach cell. How?
• Diffusion: movement of molecules due to random, spontaneous thermal motion. Net movement occurs along a gradient (chemical ± electrical).• Cell Membrane Diffusion: video
• Chemical potential: concentration gradient; charged particles