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Organic Compounds © 2010 Pearson Education, Inc. ORGANIC COMPOUNDS A cell is mostly water. The rest of the cell consists mainly of carbon-based molecules. Carbon forms large, complex, and diverse molecules necessary for life’s functions. Organic compounds are carbon-based molecules. © 2010 Pearson Education, Inc. Carbon Chemistry Carbon is a versatile atom. It has four electrons in an outer shell that holds eight. Carbon can share its electrons with other atoms to form up to four covalent bonds. © 2010 Pearson Education, Inc. Form & Function of Organic Molecules Each type of organic molecule has a unique three-dimensional shape. The shapes of organic molecules relate to their functions. © 2010 Pearson Education, Inc. Properties of Organic Compounds The unique properties of an organic compound depend on Its carbon skeleton The atoms attached to the skeleton The groups of atoms that usually participate in chemical reactions are called functional groups. Two common examples are Hydroxyl groups (-OH) Carboxyl groups (C=O) © 2010 Pearson Education, Inc. Giant Molecules from Smaller Building Blocks Organic macromolecules are large polymers. Three categories of macromolecules are Carbohydrates Proteins Nucleic acids © 2010 Pearson Education, Inc. Polymer Formation Polymers are made by stringing together many smaller molecules called monomers. A dehydration reaction Links two monomers together Removes a molecule of water Short polymer Monomer Dehydration reaction Longer polymer a Building a polymer chain © 2010 Pearson Education, Inc. Breaking up Polymers Organisms also have to break down macromolecules. Hydrolysis Breaks bonds between monomers Adds a molecule of water Reverses the dehydration reaction © 2010 Pearson Education, Inc. LARGE BIOLOGICAL MOLECULES There are four categories of large molecules in cells: Carbohydrates Lipids Proteins Nucleic acids Lipid is the only large molecule that isn’t also a macromolecule © 2010 Pearson Education, Inc. Carbohydrates Carbohydrates are sugars or sugar polymers. They include Small sugar molecules in soft drinks Long starch molecules in pasta and potatoes © 2010 Pearson Education, Inc. Monosaccharides Monosaccharides are simple sugars that cannot be broken down by hydrolysis into smaller sugars. Glucose and fructose are both monosaccharides Monosaccharides are the main fuels for cellular work. In aqueous solutions, many monosaccharides form rings. © 2010 Pearson Education, Inc. Disaccharides A disaccharide is A double sugar Constructed from two monosaccharides Formed by a dehydration reaction Glucose Galactose Lactose © 2010 Pearson Education, Inc. Polysaccharides Complex carbohydrates Made of long chains of sugar units and polymers of monosaccharides Glucose monomer Starch granules a Starch Glycogen granules b Glycogen Cellulose fibril Cellulose molecules © 2010 Pearson Education, Inc. c Cellulose Carbohydrates (cont.) Monosaccharides and disaccharides dissolve readily in water. Cellulose does not dissolve readily in water. Almost all carbohydrates are hydrophilic, or “water-loving,” adhering water to their surface. © 2010 Pearson Education, Inc. Lipids Lipids are Neither macromolecules nor polymers, but they are large molecules Hydrophobic, unable to mix with water Oil (hydrophobic) Vinegar (hydrophilic) © 2010 Pearson Education, Inc. Lipid Family The lipid family contains of: 1. Fatty acids 2. Triglycerides ( fats and oils ) 3. Phospholipids 4. Steroids ( Cholesterol, Bile Salts, Vit. D, Adrenocortical hormones, Sex hormones ) 5. Eicosanoids ( prostaglandins and leukotrienes ) 6. Others ( Carotenes, Vit. E, Vit. K, Lipoproteins ) © 2010 Pearson Education, Inc. Fats or Triglycerides A typical triglyceride, consists of a glycerol molecule joined with three fatty acid molecules via a dehydration reaction. Fatty acid Glycerol (a) A dehydration reaction linking a fatty acid to glycerol (b) A fat molecule with a glycerol “head” and three energy-rich hydrocarbon fatty acid “tails” © 2010 Pearson Education, Inc. Triglycerides Triglycerides : the most plentiful lipid in your body. It consists of two types of building blocks: a single three-carbon glycerol molecule and three fatty acid molecules. It can be either solid (fat) or liquids (oil). It's functions in the human body are for protection, insulation, and energy storage. © 2010 Pearson Education, Inc. Steroids Steroids : the structure of steroids differ from triglycerides, they have four rings of carbon atoms. Steroids are synthesized from cholesterol. Functions : 1. Cholesterol : minor component of cell membranes, precursor of other steroids 2. Bile Salts : digests dietary lipid 3. Adrenocortical Hormones : regulate metabolism, resistance to stress, have a role in salt and water balance 4. Sex hormones : stimulate reproductive functions and sexual characteristics © 2010 Pearson Education, Inc. Steroids Steroids are very different from fats in structure and function. The carbon skeleton is bent to form four fused rings. Steroids vary in the functional groups attached to this core set of rings. – Cholesterol is • A key component of cell membranes • The “base steroid” from which your body produces other steroids, such as estrogen and testosterone © 2010 Pearson Education, Inc. Cholesterol Testosterone © 2010 Pearson Education, Inc. A type of estrogen Proteins Are polymers constructed from amino acid monomers Perform most of the tasks the body needs to function Form enzymes, chemicals that change the rate of a chemical reaction without being changed in the process © 2010 Pearson Education, Inc. The Monomers of Proteins: Amino Acids All proteins are constructed from a common set of 20 kinds of amino acids. Each amino acid consists of a central carbon atom bonded to four covalent partners in which three of those attachment groups are common to all amino acids. Peptide bonds link amino acids together to form proteins © 2010 Pearson Education, Inc. Protein Structure & Function The structure of a protein is vital to its function. Proteins differ in their arrangement of amino acids. The specific sequence of amino acids in a protein is its primary structure. A slight change in the primary structure of a protein affects its ability to function. © 2010 Pearson Education, Inc. Protein Structure & Function A protein’s three-dimensional shape Recognizes and binds to another molecule Enables the protein to carry out its specific function in a cell Target Protein © 2010 Pearson Education, Inc. Protein Shape A functional protein consists of one or more polypeptide chains, precisely folded and coiled into a molecule of unique shape. © 2010 Pearson Education, Inc. Nucleic Acids Nucleic acids Are macromolecules that provide the directions for building proteins Include DNA and RNA Are the genetic material that organisms inherit from their parents © 2010 Pearson Education, Inc. Nucleic Acids DNA resides in cells in long fibers called chromosomes. A gene is a specific stretch of DNA that programs the amino acid sequence of a polypeptide. The chemical code of DNA must be translated from “nucleic acid language” to “protein language.” © 2010 Pearson Education, Inc. Nucleotides Nucleic acids are polymers of nucleotides. Each nucleotide has three parts: A five-carbon sugar A phosphate group A nitrogenous base Nitrogenous base A, G, C, or T Thymine T Phosphate group © 2010 Pearson Education, Inc. Sugar deoxyribose a Atomic structure Nucleotides Each DNA nucleotide has one of the following bases: Adenine (A) Guanine (G) Thymine (T) Cytosine (C) © 2010 Pearson Education, Inc. Sugar-phosphate backbone Base Nucleotide pair Hydrogen bond Bases a DNA strand polynucleotide © 2010 Pearson Education, Inc. b Double helix two polynucleotide strands DNA Structure Two strands of DNA join together to form a double helix. Bases along one DNA strand hydrogen-bond to bases along the other strand. The functional groups hanging off the base determine which bases pair up: A only pairs with T. G can only pair with C. © 2010 Pearson Education, Inc. RNA RNA, ribonucleic acid, is different from DNA. RNA is usually single-stranded but DNA usually exists as a double helix. RNA uses the sugar ribose and the base uracil (U) instead of thymine (T). Nitrogenous base A, G, C, or U Uracil U Phosphate group Sugar ribose © 2010 Pearson Education, Inc.