Unit 5:the Structure and Function of Macromolecules That’s a Lot of Mers!

These Themes Recur Throughout Biology There is a natural hierarchy of structural level in biological organization As we move up the hierarchy, new properties emerge due to interactions of the lower subunits Form fits function!

Polymer Principle Vocabulary Many parts MONOMER: Subunit of a polymer MACROMOLECULE: Large organic polymer

Polymer Principle There are 4 classes of organic polymers: Carbohydrates Lipids Proteins Nucleic acids

Most polymerization Reactions are condensation reactions (dehydration synthesis). This requires energy and enzymes or catalysts. Y X OH OH

A Plethora of Polymers Can be Built From a Small Set of Monomers Macromolecules are the basis for the unity and diversity of life: UNITY: 40-50 monomers are used to make all macromolecules DIVERSITY: New properties emerge when monomers are arranged in different ways.

CARBOHYDRATES Organic molecules made of sugars and their polymers Sugars are used for fuel and a carbon source Carbo monomer: Monosaccharides Polymers formed by condensation reactions Classified by the number of simple sugars

Monosaccharides Single Sugars CHO 2:1 H to 0 ratio Made in photosynthesis Energy stored in bonds Combined in condensation reactions into Di and Polysaccharides

Characteristics of a sugar OH is attached to each Carbon except 1, which is double bonded to an O (carbonyl). Aldehyde Ketone H O H C H---C---H H—C---OH C==O HO---C---H HO—C---H H---C---OH H---C---OH H H Glucose (aldose) Fructose (Ketose)

The size of the Carbon Skeleton varies from 3-7 carbons Classification Number of C’s Name TRIOS 3 Glyceraldehyde PENTOSE 5 Ribose HEXOSE 6 Glucose

The Spatial arrangement around asymmetric Carbons may vary. Glucose and Fructose are Enantiomers

In aqueous solutions, many monosaccharides form rings In aqueous solutions, many monosaccharides form rings. Chemical equilibrium favors the ring structure because of the increased stability. Linear form of glucose Ring form of glucose

Disaccharides Joined by GLYCOSIDIC LINKAGE: A covalent bond formed by a condensation Rx between two monomers. OH This is a 1-4 Glycosidic Linkage

Some Common Disaccharides Monomers Comments Maltose Glucose+Glucose Used in Beer Making Lactose Glucose+Galactose Sugar in Milk Sucrose Glucose+Fructose Table Sugar

Polysaccharides Structural and Storage roles Polymers of a few 100-1000 monosaccharides Formed by linking monomers in enzyme-mediated condensation reactions 2 Main Functions 1.)Energy Storage: starch and glycogen 2.)Structural Support: cellulose and chitin

STORAGE: STARCH Glucose polymer Storage in plants Helical glucose polymer with alpha 1-4 linkage (Campbell 5.6) Stored as granules within plant organelles called PLASTIDS Amylose: Unbranched polymer Amylopectin: Branched polymer Most animals have digestive enzymes to hydrolyze starch

STORAGE: GLYCOGEN Large glucose polymer more highly branched than amylopectin Storage polysaccharide in animals Alpha 1-4 and alpha 4-6 linkages Stored in muscle and liver of vertebrates

Structural Polysaccharides CELLULOSE Linear and unbranched Polymer of D-glucose In alpha 1-4 and beta 4-6 linkages Major component of plant cell walls Differs from starch in it’s glycosidic linkages Can’t be digested by most organisms: They can’t hydrolyze the B-4 linkage CHITIN Polymer of amino sugar (Campbell 5.9): Beta glucose with an N group replacing hydroxyl on C-2 Forms exoskeletons Can form cell walls in some fungi