The Molecules of Life All depend on mainly a handful of elements, namely: HOCNSP Hydrogen, Oxygen, Carbon Nitrogen Sulfur Phosphorus in proteinsin nucleic acids The basis of every organic substance

Why Carbon? Four outer electrons Makes up to four bonds Least electronegative non-metal High affinity for H & O

Why Carbon? Those four bonds can be arranged in space in various ways: tetrahedral, planar; as single, double or triple bonds.

Carbon bonds are strong enough for even very large molecules; they are covalent bonds.

Oxygen Six outer electrons Makes up to two bonds Highly electronegative non-metal High affinity for electrons = polar covalent bonds

Types of Bonds Unequal sharing of electrons An intra- molecular force Transfer of electrons between a metal atom & a non- metal atom Attraction between H in one molecule and O, S, or N in another An inter- molecular force Equal sharing of electrons An intra- molecular force

Functional Groups Arrangements of atoms that confer specific properties to a molecule, help us identify a type of molecule, or predict reactions. Hydroxyl = alcohols Amino = amino acids, proteins Ester = in DNA & RNA Carbonyl = in simple carbohydrates Ether = in some simple sugars

Functional Groups Can you identify the functional groups? Ethanol Ritalin Theobromine (in chocolate) Caffeine Capsaicin (in hot peppers)

Carbohydrates C, H, and O in a 1:2:1 Ratio Monosaccharides (simple sugars) Glucose, Fructose & Galactose Disaccharides (double sugars) Glucose + Glucose = Maltose Glucose + Fructose = Sucrose Glucose + Galactose = Lactose Formed by dehydration synthesis reactions Glucose Fructose Galactose Sucrose

Carbohydrates Polysaccharides (starches) Sugars are the building blocks, or monomers, of starches. Because they’re made of many repeating units, starches are considered polymers.

Carbohydrates Sugars = quick energy ; starches = storage, slower energy In animals, the storage starch is Glycogen (branching) In plants, the structural starch is Cellulose (straight chain); storage is Amylose. Glycogen

Lipids Fats & Oils C, H, O in no specific ratio Simple fat = 1 molecule of glycerol + 3 molecules of fatty acid Fatty acids are either saturated (all single bonds, C-C) or unsaturated (have double C=C bonds, or triple bonds) Also formed by dehydration synthesis & digested by hydrolysis.

Lipids Replace one fatty acid with a phosphate group (PO4) and you get a phospholipid, the crucial component of any cell membrane. Very important property is that they’re amphoteric; that is, part of the molecule mixes with water ( it’s polar) and another part doesn’t (nonpolar) Hydrophobic vs. Hydrophilic Most lipids are hydrophobic only. Bilayer

Lipids Because they’re amphoteric, they interact with water in a specific way: Heads like water Tails fear water Hydrophilic heads arrange themselves facing water; Hydrophobic tails arrange themselves facing one another Solid micelles Hollow liposomes Large bilayers

Lipids These hydrophobic – hydrophilic interactions are how detergents & soaps work: they’re amphoteric, too! Dirt & grime tend to be nonpolar, or oily; the detergent molecule’s tails grab dirt and pull it away.

Lipids Get enough phospholipids together, stick in some proteins & other molecules, and you get a cell membrane (more about these soon!)

Lipids A special category of lipid are the sterols. Best known one is cholesterol, a component of cell membranes & vital for the production of steroid hormones.

Proteins Also called Polypeptides C, H, O, but also N, S Amino Acids are the monomers of proteins AA are held together by a peptide bond. Very large, very complex molecules. Many different types: Structural Enzymes Cell identity, adhesion Receptors Hormones

Proteins

Proteins Four levels of structure: Primary 1 o = chain of amino acids Secondary 2 o = twist or fold that chain (  helix,  pleat) Tertiary 3 o = Fold it on itself again (held together by H-bonds) Quaternary 4 o = Put two or more 3 o structures together.

Proteins To remember their roles: “Proteins are TEACHERS” TRANSPORT ENZYMES ANTIBODIES & ANTIGENS CONTRACTILE HORMONES EXTRA STORAGE RECEPTORS STRUCTURE

Proteins To remember their roles: “Proteins are TEACHERS” TRANSPORT ENZYMES ANTIBODIES & ANTIGENS CONTRACTILE HORMONES EXTRA STORAGE RECEPTORS STRUCTURE

Dehydration Synthesis & Hydrolysis All of these macromolecules are made by dehydration synthesis reactions -These are reactions where H + OH are removed from two molecules, forming H 2 0 & create a bond. -Also called Condensation reactions When they are broken down, this happens by adding H + OH to a bond, breaking it. It’s like using water to break a bond. -Water = hydro -Breaking = lysis -Hydrolysis Reaction Making Sucrose Breaking Sucrose

Can you identify these?