AP Bio Unit 1 Chapter 3 Macromolecules.pdf

Organic Molecules Organic compound vs Inorganic compound Four classes of organic compounds central to life: – Carbohydrates – Proteins – Lipids – Nucleic Acids  Polymer Principles Most macromolecules are polymers. – Polymer = large molecule consisting...

Organic Molecules Organic compound vs Inorganic compound Four classes of organic compounds central to life: – Carbohydrates – Proteins – Lipids – Nucleic Acids  Polymer Principles Most macromolecules are polymers. – Polymer = large molecule consisting of many identical or similar subunits connected together. – Monomer = subunit or building block molecule of a polymer. – Macromolecule = large organic polymer Formation of macromolecules from smaller building block molecules represents another level in the hierarchy of biological organization. Four classes – Carbohydrates, Lipids, Proteins, Nucleic Acids  Polymer Principles cont’ Dehydration reaction or Condensation reaction = polymerization reactions during which monomers are covalently linked, producing net removal of a water molecule for each covalent linkage. – Process requires energy. – Process requires biological catalysts or enzymes.  Polymer Principles cont’ Hydrolysis = a reaction process that breaks covalent bonds between monomers by the addition of water molecules. – Example: Digestive enzymes catalyze hydrolytic rxns which break apart large food molecules into monomers that can be absorbed into the bloodstream.  Polymer Principles cont’ Question – Monomers are linked into polymers by ______ _______, which involve the _________ of a water molecule. - Polymers are broken down to monomers by _______ ________, which involves the _______ of a water molecule. An immense variety of polymers can be built from a small set of monomers. Structural variation of macromolecules is the basis for the enormous diversity of life. – There is unity in life as there are only about 40 to 50 common monomers used to construct macromolecules. – There is diversity in life as new properties emerge when these universal monomers are arranged in different ways.  Carbohydrates: Fuel and Building Materials Sugars, the smallest carbohydrates, serve as fuel and carbon sources – Carbohydrates = organic molecules made of sugars and their polymers Monomers are simple sugars called monosaccharides. Polymers are formed by condensation rxns. Classified by the number of simple sugars.  Monosaccharides Simple sugar in which C, H, and O, occur in the ratio of CH2O (1:2:1). – Are major nutrients for cells. Glucose is the most common. (ring or straight chain) Fructose the second most common. Galactose; Ribose; Deoxyribose – Can be produced by photosynthetic organisms from CO2, H2O, and sunlight. – Store energy in their chemical bonds which is harvested by cellular respiration. – Their carbon skeletons are raw materials for other organic molecules. – Can be incorporated as monomers into disaccharides and polysaccharides.  Characteristics of a Sugar An –OH grp is attached to each carbon except one, which contains a carbonyl grp. Size of the carbon skeleton varies from three to seven carbon. Most common are: Classification No. of Carbons Example Triose 3 Glyceraldehyde Pentose 5 Ribose Hexose 6 Glucose  Disaccharides A double sugar that consists of two monosaccharides joined by a glycosidic linkage. – Glycosidic linkage = covalent bond formed by a condensation rxn between two sugar monomers. Example: maltose  Disaccharides Examples of disaccharides Disaccharides Monomers General Comments Maltose Glucose + Important in brewing Glucose beer Lactose Glucose + Present in Galactose Milk Sucrose Glucose + Table sugar; most Fructose prevalent; transport form in plants  Polysaccharides The polymers of sugars, have storage and structural. Polymers of a few hundred or thousand monosaccharides. Are formed by linking monomers in enzyme- mediated condensation rxns. Two important biological functions: – Energy storage (starch and glycogen) – Structural support (cellulose and chitin)  Storage polysaccharide Starch = glucose polymer that is a storage polysaccharide in plants. – Helical glucose polymer with a  1-4 linkage – Stored as granules within plant organelles called plastids – Amylose, the simplest form, is an unbranched polymer – Amylopectin is branched polymer – Most animals have digestive enzymes to hydrolyze starch – Major sources in the human diet are potatoes and grains (e.g. wheat, corn, and friuts)  Storage polysaccharide Glycogen = glucose polymer that is a storage polysaccharide in animals. – Large glucose polymer that is more highly branched ( 1-4 and 1-4 linkages) than amylopectin. – Stored in the muscle and liver of humans and other vertebrates.  Structural polysaccharides Cellulose = linear unbranched polymer of D-glucose in  1-4,  1-4 linkages – Major structural component of plant cell walls. – Differs from starch in its glycosidic linkages Starch Cellulose Glucose Glucose monomer monomers  configuration  configuration  1-4 linkages  1-4 linkage  Structural polysaccharides Chitin – Structural polysaccharide that is a polymer of an amino sugar Forms exoskeletons of arthropods Found as a building material in the walls of some fungi Monomer is an amino sugar, similar to beta-glucose with a nitrogen-containing group replacing the hydroxyl on carbon 2  Lipids Insoluble in water Include fats, oils, and waxes Many have three fatty acids attached to a glycerol molecule. (Triglyceride) Fatty acids – Saturated – Unsaturated Monounsaturated and polyunsaturated  Lipids Phospholipids – Similar to triglycerides except that one of the fatty acid chains is replaced by a phosphate group. – Phosphate and glycerol are polar. – Structural foundation of cell membranes. Steroids – Backbone of four linked carbon rings – Includes cholesterol and hormones, including testosterone and estrogen.  Proteins Central to almost every life function. A protein is a functional molecule that consists of one or more polypeptides, each folded into a specific 3D-shape. – Polypeptide is a polymer of amino acids. Monomer = Amino acid – Review page 53 for the 20 amino acids of proteins – 3 categories Hydrophobic (Non-Polar); Hydrophilic (Polar) Ionic or charged (positive or negative)  Overview of Protein Function review page 52 Enzymatic proteins Storage proteins Hormonal proteins Contractile and motor proteins Defensive proteins Transport proteins Receptor proteins Structural proteins Four Levels of Protein Structure (review pages 56-57) Primary structure – The number and order (sequence) of amino acids. – Dehydration reaction – Covalent bonding – Coded by DNA  Four Levels of Protein Structure CONT’ secondary structure – Contributes to the protein’s overall conformation. – Stabilized by hydrogen bonds between the oxygen ( with a partial negative charge) of one peptide bond and the partially positive hydrogen attached to the nitrogen of another peptide bond.  Four Levels of Protein Structure CONT’ secondary structure – Alpha helix Is a coil produced by hydrogen bonding between every fourth peptide bond (3.6 amino acids per turn) – Beta pleated sheets Sheets of parallel chains folded into accordion pleats Regions are held together by either intrachain or inter chain hydrogen bonds (between adjacent polypeptide. Make up the dense core of many globular proteins (e.g. lysozyme) and the major portion of some fibrous proteins (e.g. fibroin, the structural protein  Four Levels of Protein Structure CONT’ Tertiary structure – Three-demensional shape of a protein – Types of bonds contributing to tertiary structure Weak interactions – Shape is stabilized by the cumulative effect of weak interactions. » Hydrogen bonding between polar side chains. » Ionic bonds between charged side chains » Hydrophobic interactions between nonpolar side chains in protein’s interior  Four Levels of Protein Structure CONT’ Tertiary structure – Strong interactions Covalent linkage – Disulfide bridges form between two cysteine monomers brought together by folding of the protein.  Four Levels of Protein Structure CONT’ Quaternary structure – Structure that results from the interactions between and among 2 or more polypeptides chains Example – Collagen = a fibrous protein with three helical polypeptides supercoiled into a triple helix – Hemoglobin = globular protein that has four subunits.  Mutation: Change in the primary structure (review page 58) Sickle-Cell Disease – Inherited disorder – A change in one amino acid affects the structure of the hemoglobin molecule Causing red blood cells to deform into a sickle shape that clogs tiny vessels.  Denaturing Proteins The bonds and interactions that maintain the three-dimensional shape of proteins may be disrupted by: – pH – Salt concentration – Temperature Causing the protein to unravel.  Nucleic Acids Informational polymers Nucleic acids store and transmit heredity information Two types of nucleic acids – DNA- deoxyribonucleic acid – RNA- ribonucleic acid Flow of information – DNA → RNA → protein  Nucleic Acids A nucleic acid strand is a polymer of nucleotides – Monomer = nucleotide Three parts – Nitrogenous base » Pyrimidines → cytosine, thymine, and uracil » Purines → adenine and guanine – Pentose sugar – Phosphate group