CHAPTER 5 THE STRUCTURE & FUNCTION OF MACROMOLECULES CARBOHYDRATES, LIPIDS, PROTEINS, NUCLEIC ACIDS

Objectives: n Macromolecules are polymers n Sugars (smallest carbohydrate) are used for fuel and carbon sources n Polysaccharides (polymers of sugar) have storage and structural roles n Fats store large amounts of energy n Phospholipids are a part of the cell membrane n Steroids = cholesterol and hormones n Proteins' function depends on its shape n Nucleic Acids store and transmit hereditary info n RNA and DNA

Root Words: n Con – n Di – n Glyco – n Hydro – n Macro – n Meros – n Mono – n Poly – n Tri –

MOLECULES TO RECOGNIZE Basic Protein Structure Cellulose Amino Acid Structure Glycogen Steroids Glucose Phospholipids

The Synthesis & Breakdown of Polymers. Fig. 5.2

Monosaccharides - Simple Sugars (Fig. 5.3) Note: Asymmetric Carbons in Hexose Sugars:

Carbohydrates - “Carbon” “Hydrated” ( 1:2:1 ratio ) ( C ) ( H 2 O ) ( 1:2:1 ratio ) ( C ) ( H 2 O ) Sugars - Major role - Energy. Fig. 5.4)

Disaccharide - Dehydration Synthesis & Glycosidic Linkage. (Fig. 5.5) Sucrose = Glucose & Fructose Lactose = Glucose & Galactose 1-4 & 1-2 Linkage

Starch is in the form of Amylose & Amylopectin (Fig. 5.7) (in PLANTS)GLYCOGEN is also called animal starch, stored in muscles & liver.

POLYSACCHARIDES -3 OR MORE MONOSACCHARIDES. 1. Structural: a. Cellulose - cell walls of plants. b. Chitin - exoskeleton of arthropods (insects; spiders etc.) and exterior of mushrooms 2. Storage - Starch & Glycogen

LIPIDS - Diverse Hydrophobic Molecules (Fig. 5.10) Made of 1 glycerol & 3 fatty acids (16 to 18 carbons). C-H on fatty acids make lipids hydrophobic FATS:

Saturated Fatty Acids - have no double bonds between the carbons in the chain (solids at room temp) Unsaturated Fatty Acids - have double bonds between the carbons in the chain. (Liquids at room temp due to “kinks” in the fatty acid which prevents it from solidifying) Fat Molecules are storage for energy.

Phospholipid Second Type of Lipid: Phospholipid Have 2 fatty acids NOT 3 like lipids Major components of cell membranes. Hydrophilic head Hydrophobic tail. Kink in one fatty acid means it has double bonds (Fig. 5.12)

Phospholipid Bilayer is found in cell membrane. Fig Outside of cell Inside of cell

3rd Type of Lipid 3rd Type of Lipid - Steroids Lipids with carbon skeleton of 4 interconnected rings. Cholesterol Cholesterol - common component of cell membranes. (Fig. 5.14). Also precursor for other steroids such as hormones including sex hormones.

Sex Hormones: n What is the male sex hormone? n What is the female sex hormone?

Nucleic Acids: n DNA n RNA

Proteins Storage Structural support Transport of substances Cell to cell signaling Movement Defense against foreign substances Enzymes – speed up chemical reactions

Amino Acids n Amino acids – contain carboxyl and amine functional group n Link together by peptide bonds to form a polypeptide chain n Only 20 amino acids

Protein Structure n 4 levels –Primary Structure: precise sequence of amino acids –Secondary Structure: coils or folds within the sequence due to Hydrogen bonding. n The H bonds are weak, but can support a particular shape n Alpha (a) helix - coil n Beta (B) pleated sheet - fold

Protein Structure Cont. –Tertiary Structure: n Irregular looping and folding of the protein bc of interactions of side groups –Quaternary Structure n The addition of one or more polypeptide chains to the original structure

Changes in Protein n Denature – when a protein unravels due to changes in pH, salt concentration, temperature and environment