Transcript Chapter 4
Do Now • Draw an atom of oxygen • Draw two atoms of hydrogen bonded to one atom of oxygen • What type of bond do O and H form? • What is a covalent bond? • What is an ionic bond? • What is an isotope? Chapter 4 Organic Chemistry 4-1 Water • • • • 75% of earth’s surface Most abundant compound in living things Liquid at room temperature Expands when freezes – Necessary for life • Charged molecule – polar • E- unevenly distributed • “little magnet” • Polarity allows water to stick to others and go in between other molecules Water Molecule • Cohension – water sticking to water • Adhesion – water sticking to other things Hydrogen Bonding Mixtures • Substances are physically mixed but have not formed new chemical bonds • Different substances in a mixture retain their usual properties • Ex. Table salt and iron filings, sugar and sand • Homogeneous – spread evenly throughout Solutions • Solutions - Mixtures that are liquid • Solvent - the liquid substance that makes up the bulk of the solution • Water is the universal solvent. • Solute – other substances that are dissolved in the solvent • Concentration – the measurement of the amount of solute dissolved in a fixed amount of solution • Aqueous solutions – solutions in which water is the solvent Solutions • When ionically bonded compounds dissolved in water they dissociate or break apart into individual ions • NaCl Na+ + Cl• HCl H+ + Cl- H+ • • • • Most chemically reactive ion Single proton – no eAttacks chemical bonds Acids release H+ Bases • NaOH Na+ + • Bases release OH - OH - • Strong acids and bases are highly reactive – attack and break chemical bonds – dangerous to living tissues Neutralization Reaction • Mixing an acid and a base OH- cancels H+ • H+ + OH- H2O Acids and Bases • pH – a measure of the relative amounts of hydronium (H3O or H+) and hydroxide ions (OH ) • pH = power of hydrogen • In water these ions form naturally • Pure water contains equal numbers of H+ and OH- ions • Neutral – OH = H+ pH Scale • • • • Ranges from 0 to 14 0 is very acidic – H+ 7 is neutral OH = H+ 14 is very basic (alkaline) OH • A difference of 1 on the pH scale is actually a difference of 10 times the strength of acids or bases Acids • Acid solution – contains many more H+ ions that OH ions • Ex. HCl (hydrochloric acid) or H2SO4 (sulfuric acid) • Have a sour taste, produce a tingling or burning sensation if they come in contact with skin, highly corrosive when concentrated • Ex. Citric acid – oranges, lemons and grapefruits Bases • Base solution – a solution that contains many more hydroxide ions (OH ) than hydronium ions (H3O+) • Ex. NaOH • Alkaline refers to bases • Have a bitter taste, feel slippery Importance of pH • certain pH’s are needed for different reactions in the body • Certain organisms need a certain pH to live • Ex. Fish Suspensions • A mixture in which particles spread through a liquid or gas but settle overtime 4-2 Chemical Compounds in Living Things • Elements – 90 naturally occurring – 11 common in organisms – 20 trace – 96.3% of the body – C, N, O, H • In varying combinations the elements C, H, N, O make up practically all the chemical compounds in living things Inorganic Compounds • No C • Exception – CO2 • Ex. Water, minerals, salts Organic Compounds • Have C • “organic chemistry” • C makes about 2 million compounds • Carbon is unique – remarkable ability to form stable and strong covalent bonds • Carbon can form 4 single covalent bonds • Methane – CH4 – chemical formula • Structural Formula • Carbon can bond with O, N, P, S • Carbon can form chains of C atoms – unlimited length • C atoms can bond either single, double or triple • Carbon needs 4 bonds to be “happy” Carbon Atoms Form Covalent Bonds Carbon Formations • Chains • Rings • Mixes of single, double, triple bonds Polymerization • Taking smaller C compounds and joining them to form larger compounds Monomers • Small compounds • Ex. sugar Polymers • Many monomers joined together Macromolecule • A large polymer • Macro = giant • Polymerization allows us to join monomers together to get complex molecules • Ex. Alphabet – 26 letters – many combinations make many words 4.3 Compounds of Life • 4 groups of organic compounds – – – – Carbohydrates – pasta, bread Lipids – fats, oils, waxes Proteins – meat Nucleic acids – DNA and RNA Carbohydrates • Ex. Sugars and starches made of C, H, O • O to H ratio 1:2 like water, C varies • 1C:2H:1O Monosaccharides • Simplest carbohydrate • One sugar • Ex. Glucose – sugar – green plants make Fructose – in fruits Galactose – in milk • All three – C6H12O6 • The 3 differ on how the atoms are arranged • Isomer - have the same number of atoms but they are arranged differently Importance of Sugars • Contain a lot of energy • Energy stored in the bonds • Break bonds release energy Dehydration Synthesis • Complex carbohydrates made by the process of polymerization • Chemical bonds linked • Bond formed between OH-’s • Dehydration synthesis – removes a water, two monomers join • Fig. 4-12 Dissacharide • • • • Made of 2 monomers Ex. Sucrose – table sugar Maltose – malt sugar Lactose – milk sugar Polysaccharides • “many sugars” • Forms that living things use to store extra sugar • Ex. Starch, Glycogen, Cellulose Starch • How plants store extra sugar – potatoes • 100’s of glucose molecules Glycogen • How animals store extra sugar – liver and muscles • 100’s and 1000’s of glucose molecules • “animal starch” Cellulose • • • • In plants Support to plants Strength and rigidity Major component of wood Hydrolysis • • • • Splits apart polysaccharides Reverse of dehydration synthesis Water breaks the bonds Fig 4-14 Lipids • Waxes – solid at RT • Oils – liquid • Fats – solid Three Roles in Organisms 1. Store energy 2. Form biological membranes (cell membranes) 3. Chemical messengers • Lipids – fatty acids (3) + glycerol • Fatty acid – long chain of C’s with a carboxyl group (COOH) • -OH = hydroxyl group Glycerol • Organic alcohol Saturated and Unsaturated Lipids • Saturated – all C’s connected by single bonds • Unsatuarated – all C’s connected by single and double bonds • Polyunsaturated – many double bonds • Fig – 4-18 • Lipids from saturated fatty acids saturated fats • Found in meats and most dairy products • Lipids from polyunsaturated fatty acids polyunsaturated fats • Liquid at room temperature • Cooking oils • Unsaturated fats can reduce heart disease • Plants and animals use lipids to store energy • Produce more energy than carbs gram for gram Sterols and Phospholipids • Sterol - ex. Cholesterol • Important for building cells and carrying messages • Phospholipids – ½ dissolves in water ½ doesn’t • When mixed in water they form small balloon like structures = liposomes • Liposome – double layer – bilayer • Form spontaneously • Form cell membranes Proteins • • • • Contain C, H, N, O Polymers of amino acids (AA’s) AA’s – amino group on one end – NH2 Carboxyl group on the other end - COOH • NH2 and COOH can form covalent bonds • AA’s can link together • All AA’s have a similar chemical structure and differ only in R group • 20 AA’s Peptides • • • • • • Peptide bond – covalent bond joins AA’s H2O is lost when formed Dehydration synthesis Dipeptide – 2 AA’s Tripeptide – 3 AA’s Polypeptide – many AA’s - protein Protein Structure • • One or more polypeptide chains Roles: 1. Help to carry out chemical reactions 2. Pump molecules in and out of cells 3. Help cells move Enzymes are Proteins • Chemical reaction makes life possible • Speed up chemical reaction Catalyst • substance that speeds up the rate of a chemical reaction • Are not changed by the reaction • Lower the start up energy • Enzymes are catalysts – most are proteins • Enzymes speed up a reaction by binding to the reactants • Substrate – reactants that are affected by an enzyme • Active site – place on an enzyme where the substrate binds • Enzymes are very specific. Nucleic Acids • C, O, H, N, P • Polymers of individual monomers known as nucleotides • Nucleotide made of: phosphate group, 5 carbon sugar, nitrogenous base • Two – DNA and RNA • Store and transmit genetic information The End