Chemistry in Biology * see THE PERIODIC TABLE of ELEMENTS * Element – a pure substance that can’t be broken down into a simpler form of matter * see THE PERIODIC TABLE of ELEMENTS * ATOM -The simplest particle of an element that retains the properties of that element Sub-atomic particle Charge Proton +1 Neutron Electron -1 In Nucleus →

Elements Found in Living Things Carbon (C) 18.5% Hydrogen (H) 9.5% Oxygen (O) 65% Nitrogen (N) 3.3% Phosphorus (P) 1.0% Sulfur (S) 0.3% Others… K, Ca, Na

BONDING Compound – A substance containing atoms of 2 or more elements bonded together Covalent Bond → electrons are shared Ionic Bond → electrons are transferred

COVALENT BOND

IONIC BOND

WATER Remember: Electrons are shared in a covalent bond *** But not necessarily shared evenly A molecule is said to be POLAR if it has an uneven charge distribution like this Characteristics of POLAR Compounds: Hydrogen Bonding Attraction (“polar likes polar”) Temperature Moderation Water’s Surface Tension

SOLUTIONS A solution is saturated when no more solute can dissolve A mixture of 2 or more substances Uniformly distributed SOLUTE dissolved into a SOLVENT CONCENTRATION – a measurement of the amount of solute dissolved in a fixed amount of solvent A solution is saturated when no more solute can dissolve AQUEOUS SOLUTION – a solution in which water is the solvent *** THINK ABOUT LIVING SYSTEMS *** (your body cells!)

Potential of Hydrogen A water molecule can break up (dissociate) 2 H20 ↔ H30+ + OH- (Hydronium ion) + (hydroxide ion) ACID SOLUTION – hydronium ions outnumber hydroxide ions BASE SOLUTION – hydroxide ions outnumber hydronium ions (a.k.a. alkaline solution) pH scale acidic neutral basic ]____________________________________________[ 0 7 14 stomach acid Urine Water Intestinal Fluid

Organic Compounds Carbon can make 4 bonds Organic compounds have a carbon backbone STRUCTURE: Monomer – single, simple structural unit Polymer – repeated, linked chain of monomers Condensation Reaction – Forms polymers; water molecule is given off in the process Hydrolysis Reaction – Breaks polymers; water molecule is used in the process

GLUCOSE

Condensation (dehydration synthesis)

Hydrolysis

ENERGY TRANSFER Reactants → Products BUT: Not all reactions were created equal Exergonic/Exothermic – A chemical reaction that results in a release of energy Endergonic/Endothermic – A chemical reaction that results in an absorption of energy Activation Energy - The energy needed to start a reaction

CATALYST - A substance that reduces the activation energy of a reaction ENZYME - Acts as a catalyst in a living system Usually a protein

ENERGY CURRENCY Making of a bond (~) in ATP The energy currency for the cell is a molecule called … Adenosine Triphosphate (ATP) A = Adenosine ATP = A ~ P ~ P ~ P P = Phosphate ADP = A ~ P ~ P ~ = chemical bond AMP = A ~ P Breaking of a bond (~) in ATP releases energy (EXERGONIC) A~P~P~P → A~P~P + P + ENERGY Making of a bond (~) in ATP “bottles up” energy for later use (requires energy input) A~P~P + P + ENERGY → A~P~P~P