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Chemical Basis of Life Matter and Energy Matter- anything that occupies space and has mass solid, liquid, gas Mass-amount of matter a substance contains Energy potential, kinetic light, heat, electrical, chemical Basic Molecular Structure Matter is comprised of elements, 92 of which occur naturally Elements cannot be broken down into simpler substances Identified by chemical symbols Oxygen, carbon, hydrogen, and nitrogen make up 96% of body’s mass Compounds are combination of two or more elements Compound & Mixtures Compound Mixtures Combined Combined chemically physically Alters properties Retains of individual properties of components individual components Proportions may Combined in exact proportions vary Types of mixtures Solutions - homogeneous mixture Solute = dissolved substance Solvent = dissolving medium Concentrations percent molarity Colloids (emulsions) - undergo sol-gel transformations Suspensions - visible solutes that settle What is an atom? -smallest part of an element showing characteristics of that element ATOMIC STRUCTURE a tomos = “not cut” Subunits protons-located in the nucleus (+) neutrons-located in the nucleus (0) electrons-located in energy shells (-) ATOMIC CHARACTERISTICS Atomic number - number of protons in the nucleus Mass number - number of protons plus the number of neutrons Atomic weight (mass) - sum of the number of protons,neutrons, and electrons Number of protons equal the number of electrons A complete atom is electrically neutral. There is NO NET CHARGE! Atomic Structure Isotopes atoms with the same numbers of protons but have different numbers of neutrons isotopes of an element react in the same manner chemically Radioisotopes Heavier isotopes are usually radioactive Examples Carbon 14 Iodine -131 Radium - 226 Cobalt - 60 Electron shells electrons orbit the nucleus of an atom in shells/energy levels 1st level - holds 2 e’s 2nd level - up to 8 e’s 3rd level - up to 18 number and arrangement of electrons determine if an atom is chemically stable CHEMICAL BONDS A. Chemical bonds and electrons 1. chemical bonds are a union between atoms caused by the sharing or exchange of electrons. 2. the type of bond is determined by the arrangement of the electrons in orbit around the nucleus. 3. electrons are attracted to protons, but repelled by other electrons 4. electrons are arranged in orbits (orbitals) around the nucleus. 5. the electrons in the outermost orbital are called the valence electrons 6. valence electrons determine the chemical reactivity of an atom. 7. octet rule - atoms form bonds to have 8 electrons in their valence shell CHEMICAL REACTIONS Molecule - two or more atoms joined together ex. H-H; O=O Compound - combination of atoms of two or more elements ex. CO2, H2O Chemical Equations Reactants – left side of the equation Products – right side of the equation Molecular Formula Example C6H12O6 + 6O2 ----- 6CO2 + 6H2O + Energy Patterns of Chemical Reactions Synthesis = combination Decomposition = breakdown Displacement = reactants exchange Oxidation Reduction reactants lose or gain electrons oxidized - loses electrons reduced - gains electrons Factors affecting reactions Temperature Particle Size Concentration Catalysts CHEMICAL BONDS Covalent - involve the sharing of electrons between atoms Ionic - bonding involving the loss or gain of electrons thus forming ions cation (+) anion (-) Polar covalent - due to the unequal sharing of electrons between atoms Hydrogen - type of covalent bond due to sharing of hydrogen electrons with neighboring hydrogen atoms INORGANIC MOLECULES Electrolytes Acids Bases Salts pH Water ELECTROLYTES Substances that ionize and dissociate in water and are capable of conducting an electrical current Form charged particles (ions) in solution Include acids, bases, and salts ACIDS and BASES Acid = substance that releases hydrogen ions (H+) in solution Acts as a proton donor HCl ----> H+ + Cl- Base = substance that dissociate in solution into hydroxide (OH-) Acts as a proton acceptor NaOH ---> Na+ + OH- pH - measure of acidity or alkalinity pH 7.0 - neutral acidic - pH < 7.0 basic - pH > 7.opH = - log [H+] pH - range 0 - 14 body fluids = 7.35-7.45 (7.40) SALTS Acids and bases react with other to form salts when mixed in equal concentrations HCl + NaOH H2O + NaCl (salt) WATER Excellent solvent Polarity Serves as a reactant Important lubricant High heat of vaporization High heat capacity ORGANIC MOLECULES Contain carbon atoms linked to each other in chains or rings -carbohydrates, proteins, lipids, nucleic acids CARBOHYDRATES INCLUDE SUGARS AND STARCHES PROVIDE MOST OF CELL’S ENERGY CARBON - HYDROGEN - OXYGEN 1 : 2 : 1 RATIO Monosaccharide simple sugars contain 3-7 carbon atoms ex. glucose, fructose, galactose Disaccharides are formed when 2 monomers are hooked together by dehydration synthesis reactions ex. sucrose (table sugar);lactose (milk sugar) Carbohydrates/Polysaccharides Complex sugars Very large macromolecules formed when long chains of simple sugars are hooked together Glycogen - storage form of glucose in animals Starch - storage form of glucose in plants PROTEINS Amino acids are the building blocks of proteins Contain carbon, hydrogen, oxygen, nitrogen 20 amino acids occur naturally Essential for cell structures and function enzymes, receptors, blood proteins, structural support PROTEIN STRUCTURE LEVELS Primary structure H Secondary structure l NH2 - C - COOH Tertiary structure l Quaternary structure R LIPIDS Contain carbon, hydrogen, oxygen but not in a 1:2:1 ratio Non-polar molecules that will not dissolve in water Functions as energy source, structural support, integral part of membrane TYPES OF LIPIDS TRIGLYCERIDES fats/oils saturated fatty acids unsaturated fatty acids Phospholipids important membrane component amphipathic Steroids sex hormones cholesterol Eicosanoids prostaglandins involved in blood clotting, inflammation, and contractions NUCLEIC ACIDS DNA - deoxyribonucleic acid RNA - ribonucleic acid Consist of nucleotides 5 carbon sugar nitrogenous base - (adenine, thymine, cytosine, guanine, or uracil (only in RNA)). phosphate group ATP Adenosine Triphosphate Main energy carrier for individual reaction needs