Chapter 6 Chemistry of Life

Elements - simple substances that make up everything in the world -can’t be broken down into simpler parts 90 naturally occurring 25 essential for life -Carbon, Hydrogen, Oxygen, Nitrogen (96% of human body) -Trace Elements (table 6.1 pg 142)

ATOMS - the building blocks of rock & living things The smallest particle of an element that has the characteristics of that element. Structures -Nucleus- contains protons (+) & neutrons (neutral but have mass) -Electron Cloud electrons (-)

Electron Energy Levels Electrons travel around the nucleus in specific regions (levels) Have a limited capacity for electrons EL-1 holds 2 electrons EL-2 holds 8 El-3 holds 8 Electrons in the outer most level = valence e-

Atoms Atoms usually contain equal numbers of electron and protons #p = #e Atoms usually have no charge He

Atomic Number Number of protons -Number of protons The number found on the top of columns (GROUP NUMBER) = number of valence electrons

Isotopes An atom that has the same # of protons and differs in the number of neutrons. Carbon-12 (6p+6n) Carbon-14 (6p+8n) H-3 He+ Li-7

Compounds Composed of 2 or more atoms of different elements H2O CO2 Oxygen Hydrogen Hydrogen

Covalent Bonds Bonds- formed by atoms to become more stable. (fill energy levels) (8) Covalent Bond-Molecules formed when two atoms share electrons Molecule-a group of atoms held together by covalent bonds

Ionic Bonds ION-Atom that gains or loses electrons (to become more stable) + or – charged Ionic bonds-formed by the attraction between two ions of different charge Chlorine (-) (receives) Sodium (+) (donates) NaCl

Chemical Reactions Chemical Reactions occur when bonds are formed or broken. Metabolism-All the chemical reactions in an organism Chemical Equations are representations of chemical reactions ReactantsProduct Number of Molecules 4NaCl (coefficient) Number of atoms of each element in a molecule H2O AlCl3 (subscript) Conservation of mass-matter is neither created nor destroyed (products = reactants)

Chemical Reactions C + O2  CO2 4C+ 4O2  4CO2 Reactants  Product

pH Chemical Reactions in organisms depend on pH Scale is 0-14 temperature, energy, amount, pH pH Scale is 0-14 0 Strong Acid 7 Neutral 14 Strong Base Acid forms H+ ions in water Base forms OH- ions in water Acid Base

Mixtures & Solutions Mixture – combination of substances that keep their own properties -you can pick out the different pieces Solution – one thing is dissolved in another -cannot pick it out

Section 6.2

Water *Universal solvent* Most important compound in Living systems Polar- has a positive end and a negative end Water molecules are held together by weak Hydrogen Bonds

Water -attracted to ions And to other polar molecules

Water -most things will expand when heated & contract when cooled WATER is the EXCEPTION!!! WATER will expand when FROZEN !!!

Diffusion -the movement of molecules from an area of high concentration to an area of low concentration Diffusion happens b/c of Brownian Motion - all atoms are in constant motion Dynamic Equilibrium - movement with no change in concentration

High Concentration Low Concentration

Section 6.3

All living organisms contain CARBON !!! Carbon can make 4 bonds!!! Polymer- a chain of smaller molecules linked together

Carbohydrates Carbon:Hydrogen:Oxygen 1:2:1 Store and release ENERGY Monosaccharides-single sugar Disaccharide- two sugar Polysaccharide-many Starch-complex (plant storage) Glycogen-stored energy Cellulose-fiber (gives plants support) Glucose

Lipids-Fats C57H110O6 Long-term energy storage Made of : Glycerol Fatty acids Saturated Fats-Long chains with single carbon bonds Unsaturated-Chains with double carbon bonds Fatty Acids Glycerol Ex: oils, wax, steroids Will not dissolve in water

Proteins C,H,O,N Make up the structures of tissues, organs & organisms Amino Acids- small building blocks of proteins 20 amino acids build every protein in the world Peptide bonds-attach amino acids to form Proteins

What proteins do: -building blocks for structure -contracting muscles -transporting oxygen -immunity -regulate other proteins -chemical rxns

Protein Shape is important Shape is determined by order of aa and their interactions with each other Shape determines structure Correct or incorrect structure can mean life or death to a cell enzymes

Enzymes Important proteins found in living organisms -speed up chemical reactions -involved in all Metabolic processes Enzymes have an Active Site **Lock and Key**

Nucleic Acids A Macromolecule that stores information in the form of a code. Made up of Nucleotides (C,H,O,N,P) DNA - the master copy of an organisms information RNA - makes copies of DNA to build new protein molecules for the organism.