Work and Energy. Synthesis Reactions. Exchange Reactions. Reaction Rates. Reversible Reactions 1/29/2012. Decoposition Reactions AB A + B

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1 Work and Energy Energy - capacity to do work What is work? Potential energy- energy contained in an object chemical energy - potential energy in bonds of molecules free energy potential energy available in a system to do useful work Kinetic energy - energy of motion; energy that is actively doing work heat - kinetic energy of molecular motion electromagnetic energy the kinetic energy of moving packets of radiation called photons hemical reactions Decoposition Reactions Large molecule breaks down into two or more smaller ones AB A + B Starch molecule 2-1 Glucose molecules (a) Decomposition reaction Synthesis Reactions Two or more small molecules combine to form a larger one Amino acids Exchange Reactions Two molecules exchange atoms or group of atoms AB+D ABD A + BD A AB + D D B A + B AB A D B A A Protein molecule (b) Synthesis reaction + BD D B (c) Exchange reaction 2-4 Reversible Reactions an go in either direction under different circumstances Law of mass action proceeds from the side of equation with greater quantity of reactants to the side with the lesser quantity Equilibrium: when ratio of products to reactants is stable reversible reax Reaction Rates an be affected by: oncentration (more reactants =?) Temperature (?) catalysts - speed up reactions! Enzymes most important biological catalysts

2 Metabolism All the chemical reactions of the body atabolism energy releasing (exergonic) decomposition reax produces smaller molecules Anabolism energy storing (endergonic) synthesis reax requires energy input production of protein or fat driven by energy that catabolism releases xidation-reduction Reactions xidation A molecule gives up electrons (or +) The molecule is oxidized in this process Reduction a molecule gains electrons (or +) molecule is reduced when it accepts electrons oxidation-reduction (redox) reactions oxidation of one molecule is always accompanied by the reduction of another Electrons are often transferred as rganic ompounds 4 categories of carbon compounds carbohydrates lipids proteins ucleotides & nucleic acids 2-9 rganic Molecules and arbon 4 valence electrons binds with other atoms that can provide it with four more electrons to fill its valence shell carbon atoms bind readily with each other carbon backbones forms long chains, branched molecules and rings forms covalent bonds with hydrogen, oxygen, nitrogen, sulfur, and other elements carbon backbone carries a variety of functional groups 2-10 Functional Groups small clusters of atoms attached to carbon backbone determines many of the properties of organic molecules ame and Symbol ydroxyl ( ) Methyl ( 3) arboxyl ( ) Structure ccurs in Sugars, alcohols Fats, oils, steroids, amino acids Amino acids, sugars, proteins Dehydration Synthesis AKA condensation reaction A hydroxyl group is removed from one monomer and a hydrogen from the next Monomer 1 Monomer 2 Dimer Amino ( 2) Amino acids, proteins Phosphate ( 2P 4) P ucleic acids, ATP (a) Dehydration synthesis Figure 2.15a

3 ydrolysis Splitting a polymer (lysis) by addition of a water molecule a covalent bond is broken All digestion reax consists of hydrolysis reactions rganic Molecules: arbohydrates hydrophilic organic molecule general formula ( 2 ) n n = number of carbon atoms for glucose, n = 6, so formula is Dimer Monomer 1 Monomer (b) ydrolysis Figure 2.15b Monosaccharides Disaccharides Simplest carbohydrates simple sugars 3 important monosaccharides glucose, galactose and fructose same molecular formula Isomers! produced by digestion of complex carbohydrates Glucose 2 Galactose 2 Fructose 2 composed of 2 monosaccharides 3 important disaccharides sucrose - table sugar lactose - sugar in milk glucose + galactose maltose - grain products glucose + glucose Sucrose 2 Lactose 2 Maltose Figure Figure Polysaccharides long chains of glucose 3 polysaccharides of interest in humans Glycogen: energy storage in animals made in liver, muscles, brain, uterus, and vagina Starch: energy storage polysaccharide in plants only significant digestible polysaccharide in the human diet arbohydrate Functions quickly mobilized source of energy all digested carbohydrates converted to glucose oxidized to make ATP onjugated carbohydrate: bound to lipid or protein Glycolipids: cell membrane Glycoproteins: cell membrane proteoglycans (arb. dominant & peptide/or protein) gels that hold cells and tissues together ellulose: structural molecule of plant cell walls (fiber)

4 ( 2) 5 3 1/29/2012 rganic Molecules: Lipids hydrophobic organic molecule composed of carbon, hydrogen and oxygen high ratio of hydrogen to oxygen More energy than carbs! Five primary types in humans fatty acids triglycerides phospholipids Eicosanoids (prostaglandins) steroids 2-19 Fatty Acids hain of 4 to 24 carbon atoms carboxyl (acid) group on one end, methyl group on the other and hydrogen bonded along the sides lassified saturated - carbon atoms saturated with hydrogen unsaturated - contains = bonds without hydrogen polyunsaturated contains many = bonds Palmitic acid (saturated) 3 ( 2 ) 14 Figure Lipids - Triglycerides Formed by condensation of 1 glycerol and 3 fatty acids Dehydration Synthesis structural foundation of cell membrane fatty acid tails are hydrophobic phosphate head is hydrophilic Phospholipids P 2 3 itrogencontaining group (choline) Phosphate group Glycerol ydrophilic region (head) ( 2) 5 ( 2) 12 3 Fatty acid tails ydrophobic region (tails) (a) (b) 2-36 Eicosanoids (prostaglandins) hemical regulators produced in all tissues role in inflammation, blood clotting, hormone action, labor contractions, blood vessel diameter Steroids 3 6- rings bonded to a 5- ring holesterol precurser from which other steroids are synthesized synthesized only by animals especially liver cells important component of cell membranes required for proper nervous system function Figure

5 1/29/2012 rganic Molecules: Proteins Representative Amino Acids Some nonpolar amino acids Some polar amino acids protein - a polymer of amino acids amino acid central carbon with 3 attachments amino group (2), carboxyl group () and radical group (R group) 20 amino acids differ only in functional (R) group Essential A.A.s 2-25 Methionine ysteine 2 2 S 3 2 S Tyrosine Arginine ( 2) 3 2 (a) ote: they differ only in the R group 2-26 aming of Peptides Structure of Proteins peptide molecule composed of two or more amino acids joined by peptide bonds amino group of one A.A. bonds to carboxyl group of other A.A. dehydration synthesis/condensation Peptides named number of amino acids dipeptides have 2 tripeptides have 3 oligopeptides < 15 polypeptides > 15 proteins have > 50 R 1 Amino acid 1 R 1 + A dipeptide R 2 Amino acid R 2 Alpha helix Amino acids Peptide bonds Beta sheet hain 1 hain 2 Primary structure Sequence of amino acids joined by peptide bonds Secondary structure Alpha helix or beta sheet formed by hydrogen bonding Beta chain eme groups Alpha chain Tertiary structure Folding and coiling due to interactions among R groups and between R groups and surrounding water Alpha Quaternary structure chain Association of two or more polypeptide chains with each other Beta chain Peptide bond Denature 2-28 Protein Functions Structure communication (hormones/receptors) Membrane Transport channels in cell membranes carrier proteins on cell membranes Muscle activity atalysts (enzymes) Immunity/Protection (recognition/antibodies/clotting proteins) Movement (motor proteins) - ell adhesion Enzymes Enzymes - function as biological catalysts permit reactions to occur rapidly Substrate: substance an enzyme acts upon Products: result of chemical reax aming onvention ends in ase Lipase = enzyme digests Lipids Protease = digests proteins Deoxyribonuclease = digests??

6 Free energy content 1/29/2012 Energy level of reactants Enzymes and Activation Energy Activation energy et energy released by reaction Activation energy et energy released by reaction Enzyme Structure and Action Substrate approaches active site on enzyme molecule Substrate binds to active site forming enzyme-substrate complex highly specific fit enzyme-substrate specificity Reaction products released Energy level of products Time (a) Reaction occurring without a catalyst Time (b) Reaction occurring with a catalyst 2-31 Enzyme remains unchanged and is ready to repeat the process 2-32 Enzymatic Reaction Steps 1 Enzyme and substrate Sucrose (substrate) Active site Sucrase (enzyme) 2 Enzyme substrate complex Glucose Fructose 3 Enzyme and reaction products Figure 2.27 Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the ormal or Slide Sorter views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at Enzymatic Action: Important Points!! Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the ormal or Slide Sorter views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at Reusability of enzymes Astonishing speed one enzyme molecule can consume millions of substrate molecules per minute Factors that change enzyme shape p and temperature

7 ofactors and oenzymes ofactors: inorganic non-protein helper (iron, copper, zinc, magnesium and calcium ions) binds to enzyme induces a change in shape, which activates active site oenzymes organic cofactors derived from water-soluble vitamins (niacin, riboflavin) accept electrons from an enzyme in one pathway and transfer them to an enzyme in another 2-37 oenzyme AD + Glycolysis Aerobic respiration Glucose Pyruvic acid ADP + ATP Pyruvic acid Figure 2.28 AD + transports electrons from one metabolic pathway to another P i 2-38 Metabolic Pathways Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the ormal or Slide Sorter views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at hain of reactions, with each step usually catalyzed by a different enzyme A B D A is initial reactant, B+ are intermediates and D is the end product Regulation of metabolic pathways activation or deactivation of enzymes cells can turn on or off pathways 2-40 rganic Molecules: ucleotides Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the ormal or Slide Sorter views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at 3 components of nucleotides 1. nitrogenous base 2. sugar (monosaccharide) 3. one or more phosphate groups ATP best known nucleotide adenine (nitrogenous base) ribose (sugar) phosphate groups (3)

8 ATP (Adenosine Triphosphate) Adenine 2 Ribose Triphosphate P P P 2 Adenine 2 Adenosine body s most important Ribose energy-transfer molecule Monophosphate 2 P ucleic Acids polymers of nucleotides Phosphate group, sugar, nitrogenous base DA (deoxyribonucleic acid) constitutes genes instructions for synthesizing all of the body s proteins transfers hereditary information from cell to cell and generation to generation (a) Adenosine triphosphate (ATP) (b) yclic adenosine monophosphate (camp) ATP contains adenine, ribose and 3 phosphate groups 2-43 RA (ribonucleic acid) 3 types messenger RA, ribosomal RA, transfer RA