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Chemistry of Life Unit When water, H2O, is created, hydrogen and oxygen share the electrons The oxygen has a slightly negative charge The hydrogen’s have a slightly positive charge This uneven pattern of charge creates a polar molecule = has a positive side and negative side Properties Related to Hydrogen Bonding Life depends on hydrogen bonds in water High Specific Heat = water resists changes in temp. - helps regulate cells Cohesion = attractive forces between particles of the same kind - example: surface tension of water Adhesion = the attractive forces between unlike substances - example: meniscus curve in a graduated cylinder Capillarity = the ability of water to move up through narrow tubes against gravity - due to cohesion and adhesion - example: carnations turning a different color in colored water Solutions The polarity of water makes it very effective at dissolving many substances Solvent + Solute = Solution Concentration [ ] = amount of solute in a given amount of solvent Saturated = no more solute will dissolve in the solvent Water is the universal solvent. All processes necessary for life take place in water. Acids and Bases Acid = compound that releases a hydrogen ion (H+) when dissolved in water - increases the H+ [ ] Base = compound that remove H+ ions from a solution - lowers the H+ [ ] pH scale = amount of H+ ions in a solution 0 to 6 = acidic 7 = neutral 8 to 14 = basic buffer = compound that regulates H+ [ ] - maintains homeostasis Organic Compounds Carbon is the building block of life - can form multiple bonds (up to 4), including other carbon atoms More than 90 % of the mass of all living things are composed of combinations of just 4 elements 1) Carbon ( C) 2) Hydrogen (H) 3) Oxygen (O) 4) Nitrogen (N) Monomer = each smaller subunit molecule Polymer = large molecule that contains many monomers bonded together 1) Carbohydrates - ex: sugars, starches, cellulose, glycogen Specifics - contain elements: C, H, and O - main source of usable chemical energy for cells - major part of plant cell wall (made of cellulose) - most basic are simple sugars = monosaccharides (glucose) - bond to form polysaccharides 2) Lipids - ex: fats, oils, cholesterol Specifics - contain C, H, and O - store large amounts of energy - cell membrane made up of phospholipids - regulate body responses and sexual development - are nonpolar molecules (don’t dissolve in water) 3) Proteins Specifics - contain C, H, O, and N - Made of monomers called amino acids - 20 different amino acids build proteins - specific sequence determines structure and function 4) Nucleic Acids - work together to make proteins Types: 1) DNA 2) RNA Functions DNA – stores info to build proteins RNA – helps build proteins Chemical Reactions = change substances into different substances by breaking and forming chemical bonds Example: 6O2 + C6H12O6 1. Reactants 6CO2 2. Direction + 6H2O 3. Products Reactants = substances changed during a chemical reaction (left side) Products = substances made during a chemical reaction (right side) Bond Energy = the amount of energy that will break a bond Chemical Equilibrium = when both the reactants and products are made at the same rate * Chemical reactions release or absorb energy Types of Chemical Reactions Activation Energy = the amount of energy needed to start a reaction - is very high in most chemical reactions (especially in the body) Exothermic = chemical reaction that releases more energy than it absorbs - gives off heat (hot) - ex: cellular respiration Endothermic = chemical reaction that absorbs more energy than it releases - absorbs heat (cold) - ex: photosynthesis Enzymes Catalyst = substance that reduces the amount of activation energy that is needed to start a chemical reaction Catalysts are not changed during a chemical reaction Enzymes = a type of catalyst in living things Enzymes - almost all are proteins - work best in normal body conditions (temp. and pH) - specific shape allows only certain reactants to bind - fit like a lock and key - functions: 1) help bring substrates together and chemical reactions occur 2) decrease the activation energy of the reaction 3) increase the rate of the reaction - Reaction 1 requires more activation energy than Reaction 2 - Reaction 3 has less activation energy due to a catalyst being used