Basic structural concepts:

	Atom: smallest part of a pure substance, or element, that still has the properties of that substance
	Molecule: a particle made up of one or more atoms bound together
	Element: a pure substance, made entirely of one kind of atom (all known elements are listed in the Periodic Table)
	Compound: substance made of molecules that contain more than one kind of atom

Atomic structure and function

	Many different models exist; none are perfect  pp We'll use the Bohr model and electron cloud model first  --then later structural and space-filling models Bohr model (named for Niels Bohr) shows electrons orbiting the nucleus like planets orbit the sun     FIG Electron cloud model (ECM) shows electrons as a cloud surrounding the nucleus    anim "There is nothing worse than a sharp image of a fuzzy concept." Ansel Adams
	Nucleus:  Protons  have positive (+) charge; number of protons is "atomic number" and signifies kind of atom (which element) Neutrons have no charge; optional and variable in number (isotopes)
	Electrons Electrons have a negative (-) charge and do not affect the type of element Electrons may be present in regions called energy levels The further from the nucleus, the more energy is needed by the electron to stay there --so the higher energy levels are farther from the nucleus The lowest (first) energy level can contain up to two electrons; the next few can hold up to eight electrons each (the "octet rule") Energy levels fill from the inside out

Behavior of atoms: chemical bonds  pp

	Atoms want to be "happy" meaning having a full outer energy level
	One path to happiness: ionic bonds Occurs when an atom gives one or two electrons to another atom, giving both "full" outer energy levels Ion: charged particle (atom or group of atoms) Ions "stick" together because opposite charges attract --forming a bond Electrolyte: molecule that dissolves in water to form ions
	Another path to happiness: covalent bonds     anim Outer level is "valence" level (from Latin word for outer garment) Occurs when atoms share valence electrons (co-valent, get it?) Sharing may not be equal     pp Polar molecules occur when sharing is NOT equal  Polar molecules are hydrophilic, or "get along with water" Ions also "get along with water" Nonpolar molecules occur when sharing IS equal Nonpolar molecules are often hydrophobic, "don't get along with water"    pp

Basic structural concepts:     pp

	Macromolecule: giant molecules (many atoms, not just a few)
	Polymer: macromolecule made up of many smaller molecules called "monomers"
	Polymers are assembled by dehydration synthesis
	Polymers are disassembled by hydrolysis

Carbohydrates

	Saccharides (C6H12O6)--sugar groups that make up many carbohydrates Monosaccharides--just one saccharide group Examples: glucose, fructose, galactose     fig Also called "simple sugars" or "single sugars" Disaccharides--have two saccharide groups Examples: sucrose, maltose, lactose Also called "double sugars" Polysaccharides--have many saccharide groups Example: glycogen
	Example of function: fuel, fuel storage

Lipids

	Triglycerides: three fatty acid "tails" and one glycerol holding them together Nonpolar; hydrophobic Fuel
	Phospholipids: two fatty acid "tails" with a "head" containing glycerol and phosphate     fig Tails are nonpolar; head is polar Form bilayers in water Form cellular membranes
	Cholesterol     fig Source of steroidlipids Stabilizes phospholipid bilayers

Proteins

	Proteins are folded/twisted chains of amino acids Proteins have 50 or more amino acids; polypeptides 10-50, peptides less than 10 These different categories are used very loosely in real life Levels of protein structure (increasing degrees of structural complexity) Primary - sequence of amino acids (determined by shape) Secondary - folded (pleated sheets), twisted (helices) version  of primary structure Tertiary - folded and/or twisted version of secondary structure     fig Quaternary (optional) - combination of two or more tertiary proteins     fig Denaturation is loss of proper 3D shape (extreme temp, extreme pH can denature) Renatured proteins are those that have regained their proper shape after having been previously denatured Categories of protein shape Fibrous proteins Globular proteins (globulus "small globe or sphere") Nearly any shape that isn't "fibrous" Also sometimes called globins Structure of molecule determines function (it's all about shape)    pp Protein folding has become a vital part of our understanding of how proteins function in the body
	Structural proteins Form structures, e.g. collagen, keratin
	Functional proteins Act as "chemists" or "regulators", e.g. hormones, neurotransmitters, enzymes Enzyme action     ANIM Lower "activation energy" of chemical reactions to body temp--that is, make chemistry happen that otherwise wouldn't happen Lock-and-key model Enzyme fits substrate as a key fits into a lock Active site Allosteric site (allosteric "shape changing" effect)     anim Cofactors help enzymes Organic cofactors are coenzymes, e.g. vitamins Enzymes are specific (only work with one type of substrate)

Nucleic acids

Examples: deoxyribonucleic acid (DNA)     fig ribonucleic acid (RNA)

Encode genetic information

Structure/function of DNA discovered in 1953 by James Watson Francis Crick