Ch 3 Hydrogen bonds are the most important bonds weak but gives the water its property Hydrogen bond is a small attraction to the negative charge of the oxygen making water o The hydrogen bonds allow water to stick to itself cohesion 2 water molecule take water against gravity up to the top of a plant for capillary movement and to other molecules adhesion the little dew drops on the leaves Adhesion also causes water to form spheres and hold onto plant leaves attach to a silken spider web surface tension results from cohesion of water molecules surface tension Heat vs Temperature o Heat a form of energy total kinetic energy volume is important glass of water and ocean don t have same heat produced when kinetic energy passes from one medium to another Measure in calorie or joules sometimes o Temperature measure of energy average kinetic energy volume is not important Specific heat amount of heat needed to raise or lower 1g of a substance by 1 degree C it is not easy to raise or lower the temperature of water The specific heat of water is 1 Cal g degree Celsius Water has high heat of vaporization takes a lot of heat for it to go to liquid from gas state Water is less dense in solid state than liquid which is why ice can float Water expands as it freezes It freezes top down right now if it started freezing bottom up it would destroy sea life Water is an excellent solvent Hydrophobic don t like polar substances Hydrophilic bond with polar substances Cytoplasm concentrated aqueous solution with many small molecules and ions and very large molecules Life is an aqueous solution most biological chemistry involves solutes dissolved in water o Molecular mass mass of all atoms in a element o Molarity M moles of solute liter o Mole 6 02 x 10 23 of any objects atoms etc Daltons gram o 1 mole of atom of is 6 02 x 10 23 Look at slide for picture of the formula for Avogadro s number 1 mole of NaCl 58 g add molecular mass of each so to change the concentration you double the mass and use the same 1 L of water Which is considered polar C O Acid any substance that increases the H in solution rise in pH Base any substance that decreases the H in solution or accept more OH Behavior of acids and bases in aqueous solution is constant pH of water is usually 7 but in texas it s between 5 9 because it has other things dissolved in it Acidity increases from 7 0 and basic increases from 7 14 Most living cells exist between pH 6 5 8 0 even a slight deviation from this pH to 7 0 or 7 8 can be lethal You want weak acid as you buffering system Ocean acts as a sponge and soaks in the carbon Too much carbon can make the water acidic Ch 4 Early 1700 1800 believed that organic compounds only came from living organisms But it started to change after the first experiment when Fredrick mixed ammonium and cyanide and made urea found in execratory system Now organic chemicals are defined as those that contain carbon Miller Urey Experiment see how living organisms came to earth They wanted to mimic earth s atmosphere and see what it produced After they did their experiment they still found the organic compounds as a result Why so interested in carbon Most important element of most of the biological creatures Carbon can be arranged in diverse way you can make polar nonpolar bonds with carbon and most of them are stable in different temperatures We don t see much of hydrocarbons in living organisms but the only ones we see a lot more are in petroleum products It has tons of energy When carbon makes a double bond the bond angle becomes inflexible and cant move on its own axis so you see angles that are on the same plane Double bonds can be made anywhere Isomers are different from isotopes have different number of neutrons Isomers have the same of atoms the only thing that s different is the way they are arranged Most important ones are Enantiomers carbon has to be asymmetric All of those 4 bonds have to be different ones Functional groups all of these chemical groups that participate directly in a chemical reaction HAVE TO KNOW THESE properties structures of the functional groups o Hydroxyl group OH usually in alcohol They are polar o Carbonyl group C O most ketones have the carbonyl group inside the skeleton Can be an aldehyde or ketone Very polar and common in sugar molecule groups called ketoses or aldoses o Carboxyl group COOH The C should also be attached to an OH group Its extremely acidic Most of the time it is in the ionized form Major part of the amino acid fatty acid or pretty much any other acid ACID o Amino acid NH2 they are more basic and balance out the acidity BASIC o Sulfhydryl group SH important in stabilizing protein structures These form cross linkages o Phosphate group OPO3 2 Negatively charged very polar You ll see this in ATP phospholipids o Methyl group CH3 very important when it comes to the expression of DNA It can be added to a DNA or molecule It is non polar ATP An important source of energy L Dopa helpful in Parkinson s disease R Dopa Not helpful
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