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Macromolecules The Molecules of Life! Most macromolecules are polymers Monomer Polymer Macromolecule Polymerization Reactions Chemical reactions that link two or more small molecules to form larger molecules Condensation Reactions Also known as dehydration synthesis Monomers are linked covalently producing a net removal of water. One monomer loses an H the other an OH or hydroxyl. Requires energy and enzymes Hydrolysis breaking” A reaction that breaks the covalent bonds between monomers by the addition of water molecules “Water Structural variation Structural variation of macromolecules is the basis for the enormous diversity of life. Unity= only about 40-50 monomers Diversity- new properties emerge as various monomers are put together Carbohydrates Quick energy Made from monomers called monosaccharide Classified on the number of simple sugars Monosaccharide Simple sugars Ratio = CH2O nutrients for cell –glucose Can be made by the sun Photosynthesis Energy stored in their chemical bonds which are broken in cell respiration Carbon skeletons used for other organic molecules. Major Characteristics of sugar An OH- group is attached to each carbon except one which is double bonded to a carbonyl Size of skeleton varies 3 to 7 carbons Spatial arrangements vary 3 Monosaccharide Glucose Fructose Galactose Disaccharides sugar” Two monosaccharides joined by a GLYCOSIDIC linkage. A covalent bond between two sugar monomers resulting from a condensation reaction. “Double Examples of Disacchrides Maltose glucose + glucose= malt sugar Lactose glucose + galactose= milk sugar Sucrose glucose + fructose= fruit sugar Polysacchrides Macromolecules that are polymers of a few hundred or thousand monosaccharides 2 important biological functions Energy storage- starch/glycogen Structural support- cellulose/chitin Starch Energy storage for plants Helical glucose polymer with alpha helix 1-4 glycosidic linkages. Stored in plastids Amylose- simplest form Most animals can digest Glycogen Storage polysaccharide in animals Stored in the muscle and live of humans and other vertebrates Structural Polysaccharides Cellulose- Linear unbranched polymer of D-glucose in Beta 1-4 linkages. Major component of cell walls/ reinforces Different from starch in its glycosidic linkages! (important!) Cannot be digested by most organisms. Exception- some bacteria, fungi. Chitin A polymer of an amino sugar Forms exoskeletons of arthropods Lipids Fats, Phospholipids and Sterols Insoluble in water but will dissolve in nonpolar solvents like ether, chloroform benzene FATS composed of C,H,O Macromolecules made from: 1. Glycerol- a 3-carbon alcohol 2. Fatty Acid (carboxylic acid) A carboxyl group at one end and a attached (non polar) hydrocarbon tail Ester Linkage Bond formed between a hydroxyl group (OH-) and a carboxyl group (-COOH) Triacylglycerol- a fat composed of three fatty acids bonded to one glycerol by 3 ester linkages. SEE BOOK for pictures!!! Characteristics of fat Insoluble in water due to long fatty acid chains which have lots of nonpolar C-H bonds Vary by fatty acid composition, length, and location of Carbon to Carbon bonds. Saturated Fat No double bonds, Carbon bonded to maximum # of hydrogen's Solid at room temp Most animal fats Unsaturated Fats One or more double bonds between carbons in fatty acid tail Tail kinks at each C=C so molecules do not pack close enough to solidify. Liquid, plant fats Why is Fat important? Energy storage- 1 gram of fat has 2x the energy as a gram of polysaccharide More compact fuel reservoir than a carbohydrate Cushions vital organs Insulates against heat loss Phospholipids Compound make up of a glycerol, two fatty acids and a phosphate The head is hydrophilic The tails are hydrophobic Importance of Phospholipids Major constituents of cell membranes. Because phospholipids are ambivalent towards water. they are able to form a type of barrier around the cell’s cytoplasm. Steroids Lipids which have four fused carbon rings with various functional groups attached. See picture in book Cholesterol- an important steroid Precursor to many other steroid including Vertebrate sex hormones Has an important role in the keeping the cell membrane fluid Overproduction and over consumption can contribute to atherosclerosis Proteins Composed of Carbon, Hydrogen, Oxygen And Nitrogen Proteins are building blocks The monomers are amino acids. There are 20 amino acids which form a huge variety of proteins Polypeptide chains- polymers of amino acids arranged in a specific linear sequence and linked by peptide bonds. Protein A macromolecule that consists of one or more polypeptide chains folded and coiled into specific conformations. Each kind has its own unique 3D shape Importance of Proteins Structural support (collagen) Storage (of amino acids) Transport (hemoglobin) Signaling (Chemical messengers) Cellular response to chemical stimuli Movement (contractile proteins) Defense (antibodies) Catalysis of Biochemical reactions Enzmyes Amino Acids Building block of protein Most consist of an asymmetric carbon covalently bonded to: H O Hydrogen atom H3N+- C Carboxyl group R O Amino group Variable R group (side chain) Unique properties of Amino Acids A. acids contain both a carboxyl group and an Amino group. Since one group acts like a weak acid (carboxyl) (-) the other acts as a weak base (amine) (+) so an amino acid can exist in three anion states. Some have polar side groups, some nonpolar. Peptide Bond Covalent Bond formed by a condensation reaction that links the carboxyl group of one amino acid to the amino group of another. Has polarity with the –COOH group on one end and the NH2 group on the other Backbone= N-C-C-N-C-C A Proteins Shape 3-D unique shape Native conformation Enables a protein to recognize and bind specifically to another molecule Consequence of linear arrangement of amino acids, folded and coiled and stabilized by chemical bonds and weak interactions. Four levels of Protein Structure Primary Secondary Tertiary Quaternary Primary Unique sequence of amino acids (Like beads on a string) Pioneer in sequencing- Frederick Sanger who sequenced insulin in the late 40’s. Secondary Regular repeated coiling and folding of a protein’s polypeptide backbone Contributes to proteins overall conformation Stablized by HYDROGEN bonds between peptide linkages 2 Types: Alpha Helix and Beta Pleated See book pictures Tertiary Structure (important!) Irregular contortions of a protien due to bonding between side chains ® groups; third level of protein structure imposed on primary and secondary structure. Covalent linkage( disulfide bridges) and weak interactions (ionic bonds, hydrogen bonds and hydrophobic interactions) contribute to bonding stability. Quaternary Structure Structure that results from the interaction among several polypeptides in a single protein Example: Collagen, Hemoglobin See the book for a picture What determines protein conformation? A protein’s 3-D shape is the result of the interactions responsible for the secondary and tertiary sturcture Influenced by physical and chemical environmental conditions If altered may become DENATURED and lose its native conformation Denaturation A proteins shape can be altered by: Transfer to an organic solvent. Chemical agents that disrupt hydrogen bonds, ionic bonds and disulfide bridges Excessive heat Some can return to their original state. A proteins shape.. Even though the primary structure determines the proteins conformation, many other factors affect the final shape which can not always be determined ahead of time. Nucleic Acids Protein structure is determined by primary structure which is determined by GENES- heredity units that consist of DNA- a type of nucleic acid There are two types: DNA and RNA DNA characteristics Contains coded information that programs ALL cell activity Contains directions for its own replication Is copied and passed from one generation to the next In eukaryotic cells found primary in the nucleus Makes up genes that code for Protein Synthesis RNA characteristics Functions in the actual synthesis of proteins Sits of synthesis are on ribosomes in the cytoplasm Messenger RNA carries the encoded genetic message from the nucleus to the cytoplasm DNA---RNA---Protein What makes up a nucleic acid? Monomers are nucleotides linked together by condensation synthesis. A nucleotide is: 1. nitrogenous base (A,T,C,G,U) 2. a five carbon sugar (Pentose) 3. A phosphate group The bases Pyrimidine= nitrogenous base with a sixmembered ring made up of carbon and nitrogen atoms Cytosine, Thymine (DNA), Uracil (RNA) Purine- nitrogenous base with a 5membered ring fused to a six-membered ring: Adenine and Guanine Functions of nucleotides Monomers of nucleic acids Transfer energy from one molecule to another. (ATP) Are electron acceptors in enzyme controlled redox reactions (NAD) The structure of DNA Double helix Backbone of Sugar and phosphate. The backbone is the result of phosphodiester linkages between the phosphate of one nucleotide and the sugar of the next. The sugar is deoxyribose The bases in DNA are A,T,C,G The end………… TEST