What is the chemical basis of life? What are some of the ideas central to the chemistry of life? (Key concepts of the chemical basis of life)

How does water do all this? What allows water to facilitate life at the cellular and global level?

Hydrogen Bonds A weak force of attraction between the H on one molecule and a highly electronegative atom on another molecule

Extraordinary Properties of Water Versatile Solvent due to polarity Adhesion and Cohesion---due to H bonds High Specific Heat due to H bonds High Heat of Vap due to H bonds Expands when freezing ---due to H bonds

Ideas central to the chem of life Based on covalent bonding Carbon is the “backbone” of biomolecules Simple building code Variation on common theme in extreme Only 4 fundamental types of biomolecules Enzymes make and break the covalent bonds in the chemical reactions in the cell Isomers and polymers Condensation and Hydrolysis

Famous ions in Biology Hydronium H 3 O + and Hydroxide OH - Potassium K + ions Sodium Na + ions Calcium Ca 2+ ions Hydrogen H + ions (protons)

pH SCALE measures degree of alkalinity or aciditymeasures degree of alkalinity or acidity Ranges from 0 to 14Ranges from 0 to 14 0 – 6 acid0 – 6 acid 7 neutral7 neutral 8-14 base8-14 base

ACIDS & BASES Acids: always (almost) begin with "H" because of the excess of H+ ions (hydrogen)Acids: always (almost) begin with "H" because of the excess of H+ ions (hydrogen) –Ex: lemon juice (6), stomach acid (1.5), acid rain (4.5), normal rain (6) Facts about AcidsFacts about Acids Acids usually taste SOUR/BITTER.Acids usually taste SOUR/BITTER. You eat acids daily (coffee, vinegar, soda, spicy foods, etc…)You eat acids daily (coffee, vinegar, soda, spicy foods, etc…)

ACIDS & BASES Bases: always (almost) end with -OH because of the excess of hydroxide ions (Oxygen & Hydrogen)Bases: always (almost) end with -OH because of the excess of hydroxide ions (Oxygen & Hydrogen) –EX: oven cleaner, bleach, ammonia, sea water, blood Facts about BasesFacts about Bases Bases usually feel SLIPPERY to touch and taste BITTER.Bases usually feel SLIPPERY to touch and taste BITTER.

Elements Essential to Life About 25 of the 92 natural occurring elements are essential to life CHON = 96% liv mat CHONPS = > 99%

Review of Chemical Equation Example: H 2 O + CO 2  H 2 CO 3 reactantsproducts

A continuum view of bonding Atoms complete their valence shell in a continuum of: Nonpolar covalent with equal sharing of e- –Examples: H—H O = O Polar covalent, unequal sharing of e- –Examples: H 2 O NH 3 Ionic, with complete transfer of e- –Examples: NaCl Al 2 O 3

Weak Bonds are Bio’ly Important H bonds, hydrophobic interactions, etc Can form between different parts of a single large molecule or between molecules Help stabilize 3D shape of proteins & Nas Function in chemical signaling Hold enzymes to substrates

Biological Building Codes Covalent Bond= shared pair of electrons between 2 nonmetals H, 1 unpaired e- O, 2 unpaired e- N, 3 unpaired e- C, 4 unpaired e-

Versatility of Carbon 4 valence electrons Compatibility with many different elements Forms single, double or triple bonds Makes large, complex molecules possible –Strait chains –Branched chains –Rings

(poly = many; mer = part) Large molecules consisting of many similar subunits connected together Monomer = subunit or building block of polymer

Macromolecules are Polymers Carbohydrates = polymer of monosaccharides Lipids = polymer of fatty acids & glycerol Proteins = polymer of amino acids Nucleic Acids = polymer of nucleotides

Polymers & Molecular Diversity Unity in life: Only about 40 or 50 common monomers build macromolecules Diversity in life: New properties emerge when these monomers are arranged in different ways

Sucrose Synthesis

Hydrolysis

Making & Breaking Polymers animation animation Dehydration synthesis Link monomers Via removal of H 2 O 1 water per link (out) One monomer lose OH, other loses H Any assembling of molecules in cells Hydrolysis Disassemble polymers Via addition of H 2 O 1 water per link (in) One monomer gains OH, other gains H Any disassembly of molecules in cells