Biochemistry What is organic? Usually carbon covalently bonded to carbon Carbon-containing compounds in living things EXCLUDES carbon dioxide, carbonates, etc. What are the common elements in organic chemistry? How many bonds do they make? H = 1 O = 2 N = 3 C = 4 P = 5

Macromolecules Large molecules composed of smaller molecules Most are Polymers made of monomers Three of the classes of organic molecules are polymers Carbohydrates Proteins Nucleic acids Not all form polymers Lipids some polymerize, some don’t

Building up Macromolecules CONDENSATION Reactions (water comes out) monomers  polymers Monomers form larger molecules called polymers by condensation reactions HO H 1 2 3 4 H2O Short polymer Unlinked monomer Longer polymer Dehydration removes a water molecule, forming a new bond Sometimes Called Dehydration Synthesis

Condensation Reactions Join monomers together (creates a covalent bond) Creates a water molecule (hydroxyl (OH) from one monomer and hydrogen (H) from the other)

Breaking down Macromolecules HYDROLYSIS (means “water” to “split”) polymers  monomers Polymers disassemble HO 1 2 3 H 4 H2O Hydrolysis adds a water molecule, breaking a bond

Hydrolysis Reactions Condensation reactions in reverse Water is used up Produces monomers from polymers

Categories of Macromolecules Carbohydrates Lipids Proteins

I. Carbohydrates (Carbs) Made up of monosaccharides Polymerize to form disaccharides and polysaccharides (complex carbs) All contain carbon, oxygen, and hydrogen Usually have the formula: [C(H2O)]n Often have a ring structure:

Simple Carbs: Monosaccharides Simple sugars Sweet taste Functions fuel (quick energy) Building materials: Can be combined into polymers Examples include: Fructose – gives sweet taste to many fruits Glucose – part of metabolism, found in blood and sap Ribose (and deoxyribose) – in RNA (and DNA) Galactose – in peas, and PART of lactose

Carbs: Examples of monosaccharides Glucose Fructose Galactose Glucose Ribose Deoxyribose Find the differences and similarities

Carbs: Disaccharides Two monosaccharides covalently bonded: + = + = Examples include: sucrose (table sugar) lactose (in milk) maltose (“malt” flavoring)

Complex Carbs: Polysaccharides Many sugars covalently bonded together Examples include: Chitin: used for strength and support in insect skeletons and fungal cell walls (glucosamine) Cellulose: used for strength and support in plant cell walls (β-glucose) Glycogen: used for energy storage in animals found in human heart and muscles (α-glucose) Starch: used for energy storage in plants (a-glucose)

Carbs: Polysaccharide examples Chitin = Cellulose = Glycogen = Starch =

Carbohydrate summary Carbohydrate: 3 examples: Use in animals: Use in plants: Monosaccharides Glucose Fructose Galactose Carried in blood to supply energy to the body Sweetens fruits to help seed dispersal (attracts animals) Disaccharides Lactose Sucrose Maltose In milk to provide energy to dependent young Carried by (some) phloem (sap) to supply energy Polysaccharides Glycogen Cellulose Starch In liver and muscles for short-term energy storage Forms strong fibers in cell wall

II. Lipids Lipids are mostly non-polar molecules. Used in energy storage, membrane structure, insulation, cell-to-cell communication, buoyancy, and more. Two building blocks: /OH Glycerol:C3H8O3 Fatty acid:CH3-(CH2)x-C=O

Building Lipids Condensation to form Triglycerides Glyerol bonded to a fatty acid makes a triyeride Monoglyceride = glycerol + 1 fatty acid Diglyceride = glycerol + 2 fatty acids Triglyceride = glycerol + 3 fatty acids

Fatty acids can be saturated, unsaturated and polyunsaturated No double bonds Straight chains of carbon Stack easily Usually solid at room temperature Cis double bonds Don’t stack as well (think of Tetris) Usually liquid at room temperature Trans double bonds Mimics saturated Can solidify at room temp Clogs arteries Worse for health Polyunsaturated? Many d.b.’s very kinky (liquid) better for health

Comparing Lipids vs. Carbohydrates ~9 Calories / gram Long-term storage Non-polar (water insoluble) ~4 Calories / gram Short-term storage Polar, water soluble

The Love / Hate Relationship with Carbs and Lipids

III. Proteins Made of amino acids linked by peptide bonds There are 20 types of amino acids that we use (though many more exist)

The Amino Acids Compare each: What’s the same? What’s different?

Protein Structure Final Overall 3-D Shape ~ Primary - order of amino acids Secondary - H-bonds in backbone Tertiary - 3D shape from R-groups Quaternary - 2+ polypeptides and prosthetic groups Final Overall 3-D Shape ~ Critical point: Form fits Function!

Significance of amino acid variety The different R-groups allow a variety of shapes The active sites of enzymes have the correct polarity and/or charge to attract the substrates Non-polar amino acids can be anchored in non-polar membranes A membrane channel protein can have non-polar r-groups on the outside and polar r-groups on the inside, creating a hydrophilic passageway through the membrane

Proteins: Building (Condensation) and Breaking (Hydrolysis) Condensation (dehydration): joins amino acids into a dipeptide or polypeptide, produces water Hydrolysis: breaks a polypeptide into amino acids, uses water