Chemical Basis of Life

Chemistry Matter is made up of separate chemical components. –Chemistry = Interactions between atoms/molecules. Biological function begins at the chemical level. –Hierarchical interactions add function. –Ex. Photosynthesis

Sub-cellular concepts Matter Elements Atoms Natural elements –92 –About 25 essential for life –H,O,N,C = 96% of human body –Trace elements

Periodic Table of Elements

Atomic Structure 3 Basic subatomic particles. –Proton –Electron –Neutrons Atomic Number Atomic Mass Compounds

Isotopes Atoms representing different forms of the same element. Same number of Protons, but different mass –Different number of neutrons Radioactive Isotopes

Electrons Arranged in shells Valence Reactivity Molecules

Molecular Structure Structural formula Ball and stick

Chemical Bonding – Ionic Bonds Form between Ions of opposite charge NaCl –One atom gives up e - (cation). –One atom recieves e - (anion). –Results in filled outer shells for both.

Chemical Bonding – Ionic Bonds

Chemical Bonding – Covalent Bonds Result from electron sharing. –1 or more pairs of outer shell electrons. –Number of possible bonds = number needed to fill outer shell.

Chemical Bonding – Hydrogen Bonds Attraction between the (+) and (-) ends of a water molecule Weak bonds Hydrogen = positive end Oxygen = negative end

Water Polar molecule –Electronegativity –Polar covalent bonds Cohesion Adhesion Resistant to temperature change

More Definitions Solutions –Solvent –Solute Aqueous solution = Water is the solvent –Water = Universal solvent –Results from the Polarity

pH Potential hydrogen. H 2 O dissociates into H + and OH - (hydroxide) ions. –Acids –Bases pH scale

pH Scale

Chemical Reactions Processes producing chemical changes in matter. –Reactants –Products Matter cannot be created or destroyed Energy flow

Types of Chemical Reactions Synthesis –Ex. A + B => AB Decomposition –Ex. AB => A + B Exchange –Ex. AB + CD => AC + BD Oxidation-Reduction (redox) –Ex. C 6 H 12 O 6 + 6O 2  6CO H 2 O + ATP