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Biochemistry I. Elements and Atoms A. Elements 1. Introduction a. A substance that is made up of only one type of atom. b. 92 natural elements c. elements names are abbreviated by a symbol 2. Elements of living organisms a. living organisms are composed of 6 main elements. Carbon, hydrogen, oxygen, nitrogen, phosphorus, sulfur Table 2-1 Briefly describe some benefits and limitations of Trace Elements Trace elements Elements used by an organism in very small amounts making up less than .01% of the human body weight.. b. Examples of trace elements: iron – hemoglobin carries oxygen in the blood. A deficiency can cause anemia. iodine – normal activity of the thyroid gland. A deficiency can cause a goiter. magnesium – chlorophyll of your cells Check Your Understanding 1. Is a trace element an essential element? Explain? Yes, because an organism requires them for survival if only in small amounts. 2. Iron (Fe) is a trace element required for the proper functioning of hemoglobin , the molecule that carries oxygen in red blood cells. What might be the effects of an iron deficiency? The person can have low oxygen in the blood or too few red blood cells commonly known as anemia. Do you know what makes up the periodic table? • 1. Elements-is a pure substance that consist entirely of one type of atom. 2. Atom-the basic unit of matter(meaning it can not be cut). B. Atoms 1. Introduction a. the smallest particle of an element that has the characteristics of that element. 2. Atoms structure a. Neutrons - uncharged subatomic particles found in the nucleus b. Protons - positively charged particles found in the nucleus c. Electrons - negatively charge particles found outside the nucleus • d. Atomic number - the number of protons and electrons in a specific atom’s nucleus. • e. Atomic mass/weight - the number of protons and neutrons in a specific atom’s nucleus. This is the size of the atom. On the empty slide, create your own periodic table key for the element your teacher gives you. Atomic mass Name Atomic Number Symbol f. number of electrons equals the number of protons, therefore an atom is neutral. The positive protons and negative electrons cancel each other out, but this does not mean they are stable. g. The number of neutrons= Atomic mass - Atomic number Calculate the # of neutrons for this element 35.45-17=18 neutrons Go back to your blank slide, calculate the number of neutrons for your element. 3. Electrons and Energy levels a. electrons move in energy levels around the nucleus b. 1st level - 2; 2nd level - 8; 3rd level - 18 c. Valence Electrons- are found in the outer most energy level. Bohr Diagram show energy levels and electron # Bohr diagram for Chlorine • On the back page, create your own Bohr diagram for the element you used on your blank slide. Individual Practice Individual Practice: Create your own atom. • Using a paper plate, you will create your own atom. • Your teacher will give you the element that you must use. • Using markers you must – Add name of element – Add protons and neutrons – Add the right amount of energy levels and the correct number of electrons. Assignment Quiz grade 3-D model • • • • • Bohr Element Electrons Protons Neutrons Orbital's Periodic Table • Rows (horizontal) are called periods – Determine the energy level (orbital) • Columns (vertical) are called families or groups – Determine valance electrons (reacting electrons) – Elements in the same family react in a similar fashion ex. Both chlorine and fluorine have 7 valence e- and have a tendency to gain 1 e- 1. Attach the periodic table to IAN 2. Label the various families 3. Label the number of valence electrons (roman numeral) Alkaline “earth” metals Transition Metals Inner Transition Metals Noble Gases Halogens Alkali metals 8 C. Isotopes 1. When atoms of the same element differ in the # of neutrons they contain(still contain the same # of electrons). 2. Radioactive isotopes-nuclei are unstable and break down at a constant rate over time. (geologist can determine the age of rock and fossils by analyzing isotopes). Marble demonstration textbook pg.36 II. Interactions of Matter A. Compounds and Bonding a. compound - two or more different elements that are chemically combined (carbon dioxide) b. chemical compound-the substance formed by the chemical combination of two or more elements in definite proportions. c. properties of a compound can be very different from the elements that make it up • Covalent bonding a. the sharing of electrons between atoms b. the electrons actually travel in the orbital shell of both atoms c. the structure that results when atoms are joined together by covalent bond is a molecule(the molecule is also the smallest unit of compounds). Exercise: Tug of War 2 of the same. • Ionic bonding a. the transfer of electrons from one atom to another which will create an ion, or charged atom b. oppositely charged ions will attract to each in a bonding fashion c. atoms that loss electrons become positively charged d. atoms that gain electrons become negatively charged e. Weak bonds are important to biological process they dissociate when put into solutions Chair exercise TE Page 38 Van der Waals Forces a. When molecules are close together a weak attraction b/t oppositely charged regions of nearby molecules. Example is the gecko. What are some everyday products that demonstrate Van Der Waals Forces? • Glue and cosmetics products • How can insects and reptiles walk on water? • Water(H20) and Its Properties a.70% plus of living organism are made up of water b. Polar covalent molecule-when the charges are unevenly distributed(this is why water is polar). Note: The hydrogen's are bonded to the oxygen. Tug of war: one big one small Continued Properties of H2O -Hydrophobic interaction- when nonpolar molecules cluster together in the present of a polar substance. (example: oil in water) -Hydrophilic interaction-substances are water loving and will dissolve in water (examples sugar, ionic bonds) -Temperature stabilization - water can absorb a large amount of heat before vaporizing. (ex. High “specific heat - stabilizing the earth temp. High “heat of vaporization” - sweating) • Hydrogen bonding a. The attraction b/t the hydrogen atom on one water molecule and the oxygen atom of another water molecule. b. cohesion - the ability of water to stick to water (ex. Surface tension - animals walking on water and capillary action - xylem tubes in plants) c. adhesion- the ability of water to stick to other materials(graduated cylinder meniscus) • Mixtures, Solutions, and Suspensions. a. Mixture- a material composed of two or more elements or compounds that are physically mixed together, but not chemically. - Earths atmosphere is a mixture gases. List 3 of your own examples of mixtures: _____________, _______________, _________________ There are two types of mixtures involving water. • Solutions-when ions gradually become dispersed in water. -Solute- the substance dissolved. -Solvent- the substance in which the solute dissolves. • Suspensions-materials that do not dissolve in water, but are separated into smaller pieces that do not settle(blood). Mini-Lab 100ml graduated cylinder filled with 50ml of H2O Pour 25g of sugar into the graduated cylinder. Gently swirl the graduated cylinder in the air. Answer the questions below 1. What did you observe when the solution was swirled? Are their other methods that can give you the same result as swirling? 2. Is their any evidence that the sugar dissolved into the water? 3. Is the level of water still at the same height as before the sugar was added? What is the difference in height? 4. Explain what happened to the sugar when it was added to the water? 5. What is the solute? 6. What is the solvent? Based on previous knowledge where can you find these everyday substances on the ph-scale? • • • • • • • Human blood Rain Lemons Detergent Wine Baking Soda Bleach • Acid and bases a. acid -a substance that releases hydrogen ions (H+) in water. Ex: HCl acid b. base -a substance that releases hydroxide ion (OH-) in water. Ex: NaOH c. pH scale- the measure of the hydrogen/hydroxide concentration in a solution. Scale range is 1 - 14 -7 being neutral (water) -7 below is acidic (vinegar) -7 above is a base (ammonia) d. Measuring ph levels -ph paper tells an acid or base -litmus paper tells actual ph value e. buffer - a substance that resist changes in pH when an acid or base is added by either accepting or releasing hydrogen ions. Ex: blood Balancing Chemical Equations Writing chemical equations -Chemical equation - a description of what happens when two or more chemicals react - The number atoms in the reactant chemicals must equal the number of atoms in the product chemicals -Subscripts are used to indicate the number of atoms of each element in the molecule/compound -Co-efficent are used to indicate the number of molecules/compounds used in the reaction Sub-script Practice Balancing equations • • • • • 1. _____ H2 + _____ O2 _____ H2O 2. _____ N2 +_____ H2 _____ NH3 3. _____ S8 + _____ O2 _____ SO3 4. _____ N2 + _____ O2 _____ N2O 5. _____ HgO _____ Hg + _____ O2 Organic Chemistry The study of carbon compounds • Experiment: In 1953, Stanely set up a Fig. 4-2 EXPERIMENT “Atmosphere” closed system to simulate conditions CH4 thought to have existed on the early Water vapor Electrode earth. A flask of H2O simulated the primeval NH 3 H2 sea. The H2O was heated so that some Condenser vaporized and moved into a second, higher flask containing the “atmosphere” a mixture Cooled water of gases. Sparks were discharged in the Cold containing water organic synthetic atmosphere to mimic lighting molecules • Results: Miller identified a variety of organic molecules that are common in living organisms such as amino acids (a H2O “sea” chain of proteins required for DNA) Question: What conclusion did Stanley Sample for chemical analysis Miller draw when he found amino acids in That life molecules could have been the product experiment? synthesized from nonliving molecules III. Life substances A. The properties of carbon that make it so important. 1. Introduction a. can bond with hydrogen, oxygen, phosphorous, sulfur, and nitrogen. b. can form single, double, or triple bonds Ring Chain Branched c. freedom of bond rotation to assume a variety of shapes. Forms chains, ring shaped, or branched will affect the distinctive affect of the organic molecule. d. can form isomers-one of two or more compounds that differ in structure but has the same molecular formulas Hydrogen = Carbons= Hydrogen= Carbons= Empirical Formula: e. contains 4 valence electrons f. can form up to 4 covalent bonds Check your understanding 1. Which molecules in figure 4.5 are isomers? Butane and 2-Methylpropane and 1-Butene and 2- Butene Fig. 4-5 Ethane Propane 1-Butene (a) Length Butane (b) Branching 2-Butene (c) Double bonds 2-Methylpropane (commonly called isobutane) Cyclohexane (d) Rings Benzene Functional/Chemical groups are molecular components attached to the skeleton that will chemically react affecting molecular functions. Fig. 4-9 Estradiol Testosterone A comparison of chemical groups of female estrogen and male testosterone. Differ only in the chemical groups attached to a common carbon skeleton (shaded in blue). These subtle variation in molecular architecture distinguish one major developmental difference between man and woman. The 7 important chemical groups in biological processes 1. Hydroxyl can clean the air we breathe of pollutants 2. Carbonyl used making aldehydes and ketones 3. Carboxyl building amino acids 4. Amino builds protein chains 5. Sulfhydryl found in co-enzymes and certain proteins 6. Phosphate to release or store energy 7. Methyl can be a deadly gas. Fig. 4-10a CHEMICAL GROUP Hydroxyl Carbonyl Carboxyl STRUCTURE (may be written HO—) NAME OF COMPOUND In a hydroxyl group (—OH), a hydrogen atom is bonded to an oxygen atom, which in turn is bonded to the carbon skeleton of the organic molecule. (Do not confuse this functional group with the hydroxide ion, OH–.) The carbonyl group ( CO) consists of a carbon atom joined to an oxygen atom by a double bond. When an oxygen atom is double-bonded to a carbon atom that is also bonded to an —OH group, the entire assembly of atoms is called a carboxyl group (—COOH). Alcohols (their specific names usually end in -ol) Ketones if the carbonyl group is within a carbon skeleton Carboxylic acids, or organic acids Aldehydes if the carbonyl group is at the end of the carbon skeleton EXAMPLE Ethanol, the alcohol present in alcoholic beverages Acetone, the simplest ketone Acetic acid, which gives vinegar its sour taste Propanal, an aldehyde FUNCTIONAL PROPERTIES Is polar as a result of the electrons spending more time near the electronegative oxygen atom. A ketone and an aldehyde may be structural isomers with different properties, as is the case for acetone and propanal. Can form hydrogen bonds with water molecules, helping dissolve organic compounds such as sugars. These two groups are also found in sugars, giving rise to two major groups of sugars: aldoses (containing an aldehyde) and ketoses (containing a ketone). Has acidic properties because the covalent bond between oxygen and hydrogen is so polar; for example, Acetic acid Acetate ion Found in cells in the ionized form with a charge of 1– and called a carboxylate ion (here, specifically, the acetate ion). Fig. 4-10b CHEMICAL GROUP Amino Sulfhydryl Methyl In a phosphate group, a phosphorus atom is bonded to four oxygen atoms; one oxygen is bonded to the carbon skeleton; two oxygens carry negative charges. The phosphate group (—OPO32–, abbreviated P ) is an ionized form of a phosphoric acid group (—OPO3H2; note the two hydrogens). A methyl group consists of a carbon bonded to three hydrogen atoms. The methyl group may be attached to a carbon or to a different atom. (may be written HS—) STRUCTURE NAME OF COMPOUND Phosphate The amino group (—NH2) consists of a nitrogen atom bonded to two hydrogen atoms and to the carbon skeleton. The sulfhydryl group consists of a sulfur atom bonded to an atom of hydrogen; resembles a hydroxyl group in shape. Amines Thiols Organic phosphates Methylated compounds EXAMPLE Glycine Because it also has a carboxyl group, glycine is both an amine and a carboxylic acid; compounds with both groups are called amino acids. FUNCTIONAL PROPERTIES Acts as a base; can pick up an H+ from the surrounding solution (water, in living organisms). (nonionized) (ionized) Ionized, with a charge of 1+, under cellular conditions. Glycerol phosphate Cysteine Cysteine is an important sulfur-containing amino acid. In addition to taking part in many important chemical reactions in cells, glycerol phosphate provides the backbone for phospholipids, the most prevalent molecules in cell membranes. Two sulfhydryl groups can react, forming a covalent bond. This “cross-linking” helps stabilize protein structure. Contributes negative charge to the molecule of which it is a part (2– when at the end of a molecule; 1– when located internally in a chain of phosphates). Cross-linking of cysteines in hair proteins maintains the curliness or straightness of hair. Straight hair can be “permanently” curled by shaping it around curlers, then breaking and re-forming the cross-linking bonds. Has the potential to react with water, releasing energy. 5-Methyl cytidine 5-Methyl cytidine is a component of DNA that has been modified by addition of the methyl group. Addition of a methyl group to DNA, or to molecules bound to DNA, affects expression of genes. Arrangement of methyl groups in male and female sex hormones affects their shape and function. Overview: The Molecules of Life • All living things are made up of four classes of large biological molecules: carbohydrates, lipids, proteins, and nucleic acids • Within cells, small organic molecules are joined together to form larger molecules • Macromolecules are large molecules composed of thousands of covalently connected atoms • Molecular structure and function are inseparable Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 2. Macromolecules a. living organism make large macromolecules “know as giant molecules” b. Macromolecules are formed by a process called polymerization-building large molecules by joining smaller ones. c. monomers- are the smaller unit joined together to form polymers. d. Polymer-large compound formed from the combination of many monomers Straw exercise: http://video.google.com/videosearch?hl=en&source=hp&q=pol ymerization&um=1&ie=UTF-8&sa=N&tab=wv# b. when many monomers are chemically combined this is known as a condensation/dehydration reaction, and water is given off as a by product c. when a polymer is broken down into its many monomers, this is known as a hydrolysis reaction, and water is added. This reaction occurs in digestion Fig. 5-2b Fig. 5-2a HO 1 2 3 H Short polymer HO 1 2 1 2 3 4 H Unlinked monomer Dehydration removes a water molecule, forming a new bond HO HO H 3 Hydrolysis adds a water molecule, breaking a bond H2O 4 H2O H HO 1 2 3 Longer polymer (a) Dehydration reaction in the synthesis of a polymer (b) Hydrolysis of a polymer H HO H Bread Activity B. 4 main groups of Organic Compounds 1. Carbohydrates (polymers) a. contains carbon, hydrogen and oxygen in a 1: 2:1 ratio b. provide energy to living cells c. Monosaccharides - single sugars that serve as a major fuel for cells and as raw material for building molecules. glucose (C6H12O6) most common=sugar fructose=fruits galactose=milk D. disaccharides- linking two monosaccharide's together E. polysaccharide - many sugars formed by joining monosaccharide -Excess sugars can be stored as 1. Glycogen can release glucose from the liver when glucose levels become low. 2. Starch (spaghetti) 3. Plants store excess sugars as plant starch in the chloroplast. 4. Cellulose gives plants their strength and flexibility (wood and paper) 5. Chitin is another structural polysaccharide, is found in the exoskeleton of arthropods Chitin also provides structural support for the cell walls of many fungi Fig. 5-6 Chloroplast Mitochondria Glycogen granules Starch 0.5 µm 1 µm Glycogen Amylose Amylopectin (a) Starch: a plant polysaccharide (b) Glycogen: an animal polysaccharide Fig. 5-10 (a) The structure of the chitin monomer. (b) Chitin forms the exoskeleton of arthropods. (c) Chitin is used to make a strong and flexible surgical thread. CARBOHYDRATES Check your Understanding -Milk contains carbohydrates lactose and galactose. -Fruits contain carbohydrates fructose -Potatoes contain carbohydrates starch 1. What is the source of energy for these carbohydrates? They get energy from sunlight 2. What function do these carbohydrates serve in living things? They provide living organisms with energy 2. Lipids a. contains carbon, hydrogen, and oxygen in different ratios than carbohydrates. -The components lipids consist of are a glycerol and fatty acid Fatty Acid Chain Glycerol b. used for stored energy, insulation, protective coatings, cell membranes and as hormones c. all are insoluble in water (hydrophobic) d. steroids are also lipids e. mainly seen as fats, oils, and waxes. • Can be saturated where all the carbons have a hydrogen attached at every possible spot. No double bonds (usually solid at room temp) • Can be unsaturated carbons are double bonded resulting in a kink in the carbon chain (usually liquid a room temperature) • Polyunsaturated when fatty acids have more than one double bond (peanut oil) Fig. 5-12 Structural formula of a saturated fat molecule Stearic acid, a saturated fatty acid (a) Saturated fat Structural formula of an unsaturated fat molecule Oleic acid, an unsaturated fatty acid (b) Unsaturated fat cis double bond causes bending LIPIDS Check your Understanding 1. What are the components of a lipid? Carbon, hydrogen, oxygen in diiferent ratios than carbohydrates 2. Would you describe the picture shown to be a saturated or an unsaturated fat? Unsaturated usually liquid at room temperature 3. 4. Is saturated or unsaturated more healthy? Unsaturated Which of these substance stores the most energy? A. One gram of fat B. One gram of alcohol C. One gram of carobohydrate D. One gram of nucliec acid Bell Ringer • What are some negative effects of carbohydrates in the body? The break down of sugar molecules (diabetics) • What are some negative effects of lipids in the body? To much fat high cholesterol not being able to breaks down the fat, loss Of H2O 3. Proteins a. contain carbon, hydrogen, oxygen, nitrogen, and sulfur b. used for cell structure, as enzymes, hemoglobin, and the immune system c. monomer unit is the amino acid. 20 common variations d. all amino acid are identical in amino group and carboxyl groups. e. They differ in the R-group -can be acidic or basic -can be polar or nonpolar Table 5-1 • Enzymes are a type of protein that acts as a catalyst to speed up chemical reactions • Enzymes can perform their functions repeatedly, functioning as workhorses that carry out the processes of life Animation: Enzymes Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings e. amino acids are bonded together by peptide bonds to form polypeptides f. structural levels 1. Primary - order of amino acids 2. Secondary - coiling or sheet design 3. Tertiary - over all three-dimensional shape due to “R” groups of the amino acids 4. Quaternary - the arrangement assumed by two or more polypeptides bonding together Fig. 5-21 Sickle-Cell Disease: A Change in Primary Structure Primary Structure Secondary Structure Tertiary Structure Quaternary Structure pleated sheet +H N 3 Amino end Examples of amino acid subunits helix •A slight change in primary structure can affect a protein’s structure and ability to function •Sickle-cell disease, an inherited blood disorder, results from a single amino acid substitution in the protein hemoglobin Fig. 5-22c 10 µm Normal red blood cells are full of individual hemoglobin molecules, each carrying oxygen. 10 µm Fibers of abnormal hemoglobin deform red blood cell into sickle shape. What Determines Protein Structure? • In addition to primary structure, physical and chemical conditions can affect structure • Alterations in pH, salt concentration, temperature, or other environmental factors can cause a protein to unravel • This loss of a protein’s native structure is called denaturation • A denatured protein is biologically inactive Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 5-23 Denaturation Normal protein Renaturation Denatured protein PROTIENS Check you Understanding • Which part of the amino acid is the same in every amino acid? Amino group and carboxl group • In what way are R-groups different? Acidic or basic Polar or non-polar • Explain why proteins are considered polymers but not lipids? Proteins are made up of many monomers that become polymers. Lipids are made of gycerol and 3 fatty acid chains Nucleic acids store and transmit hereditary information • The amino acid sequence of a polypeptide is programmed by a unit of inheritance called a gene • Genes are made of DNA, a nucleic acid • There are two types of nucleic acids: – Deoxyribonucleic acid (DNA) – Ribonucleic acid (RNA) Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings 4. Nucleic acids a. contains carbon, hydrogen, oxygen, and nitrogen b. used for encoding cellular information and as carrier molecules c. monomer unit: nucleotide d. nucleotide subunits: - 5 carbon sugar (ribose or deoxyibose) -phosphate group -1 nitrogen base (adenine, guanine, cytosine, thymine, or uracil) -The order of nitrogenous bases affect the information contained (alphabet). e. two nucleic acid polymers 1. DNA - record the cellular instructions 2. RNA - reads and then carries out the instructions f. other nucleotides and their functions are: ATP - energy for the cell NAD - hydrogen carrier for chemical reactions NUCLEIC ACIDS Check you Understanding 1. What are the three basic parts of a nucleotide? 5 carbon sugar, phosphate group, and a nitrogenous base. 2. Does the sequence of nitrogenous bases effect the information it contains and how? Yes ABCDEFGHIJKLMNOPQRSTUVWXYZ Fig. 5-UN2a Fig. 5-UN2b Matter and Energy • Have you ever sat around a campfire or watched flames flicker in a fireplace? The burning of wood is a chemical reaction—a process that changes one set of chemicals into another set of chemicals. A chemical reaction always involves changes in chemical bonds that join atoms in compounds. The elements or compounds that enter into a chemical reaction are called reactants. The elements or compounds produced by a chemical reaction are called products. As wood burns, molecules of cellulose are broken down and combine with oxygen to form carbon dioxide and water vapor, and energy is released. Reactants are oxygen 1. What are the reactants when wood burns? and cellulose. 2. What are the products when wood burns? Products are carbon dioxide 3. What kinds of energy are given off when wood burns? and water. Light and heat are given off. Some students may also mention sound (the crackling a fire). 4. Wood doesn’t burn allofby itself. What must you do to start a fire? What does this mean in terms of energy? To start a fire, you must light it with a match and kindling. You are giving the wood some energy in the form of heat. 5. Once the fire gets started, it keeps burning. Why don’t you need to keep restarting the fire? Once the fire gets going, it gives off Chemical Reactions Chemical Reactions • A process that changes one set of chemicals into another set of chemicals. -some reactions happen slowly like rust Iron + Water + Oxygen => Rust Reactants Product -Reactant is the breaking of bonds -Products is the formation of new bonds -some happen quickly like hydrogen gas igniting. Balancing Chemical Equations Writing chemical equations -Chemical equation - a description of what happens when two or more chemicals react - The number atoms in the reactant chemicals must equal the number of atoms in the product chemicals -Subscripts are used to indicate the number of atoms of each element in the molecule/compound -Co-efficient are used to indicate the number of molecules/compounds used in the reaction Sub-script Practice Balancing equations • • • • • 1. _____ H2 + _____ O2 _____ H2O 2. _____ N2 +_____ H2 _____ NH3 3. _____ S8 + _____ O2 _____ SO3 4. _____ N2 + _____ O2 _____ N2O 5. _____ HgO _____ Hg + _____ O2 Energy In Reactions Energy-Absorbing Rxn. Energy-Releasing Rxn. Activation Energy Products Reactants Activation Energy Reactants Energy-Releasing Products Products Reaction • Exergonic are chemical reaction that release energy occur spontaneously (without prompting) • Endergonic are chemical reaction that absorb energy will not occur without a source of energy. Energy-Absorbing Rxn. Product Reactants Energy-Releasing Rxn Reactants Activation Energy Activation Energy Products • Check Your Understanding: • How would you compare the energy of the products and reactants in the two types of reaction graphs? Energy absorbing the products have more energy than the reactants. In a Energy releasing the products have less energy than the reactants. • Which type of graph reaction is more likely to be spontaneous Energy releasing reaction Activation Energy and Enzymes • Activation Energy is the energy needed to get a reaction started. • Catalyst is a substance that speeds up the rate of a chemical reaction. • Enzymes are proteins that speed up chemical reactions that happen in cells. Textbook Demonstration Push a book off the desk. Observe how much energy it took to push the book off the desk. Now prop the book at an angle and push the book off the desk. Did it take the same amount of energy? What represented the activation energy and the enzyme/catalyst 1.Identify the axes in the graph below? 2. What does the graph show would be the effect if enzymes were not available within the cell? 3.Would a reaction take a longer or shorter time with an enzyme? 4. What would be an appropriate title for this graph? Reaction pathway without enzyme Activation energy without enzyme Reactants Reaction pathway with enzyme Products Activation energy with enzyme Substrates Specificity of Enzymes -Enzymes provide a site where a reactant can be brought together to react. -Substrates-reactant of a enzyme catalyst reaction. -Substrates bind to a site on the enzyme called the active site (lock and key). -Enzyme-substrate complex when a enzyme binds to a substrate because there are two or more reactants present. -Activation site only a restricted region of the enzyme molecule actually binds to the substrate. -Induced fit enhances their ability to catalyze the chemical reactions. 1. Substrates enter active site; enzyme changes shape such that its active site enfolds the substrates (induced fit). 2. Substrates held in active site by weak interactions, such as hydrogen bonds and ionic bonds. Enzyme-substrate complex Active site is available for two new substrate molecules Enzyme 3. Active site can lower EA and speed up a reaction 5. Products are released 4. Substrates are converted to products. The substrate fits into the active site of the enzyme creating a induced fit(similar to the clasp of a handshake). What effects enzyme activity? • Changes in Temperature • Ph Values • Optimal ph is determined by finding the highest point and dragging straight down to the x-axis • What is the optimal ph for pepsin? 2 Fig. 8-18 Rate of reaction Optimal temperature for typical human enzyme Optimal temperature for enzyme of thermophilic (heat-tolerant) bacteria 40 60 80 Temperature (ºC) (a) Optimal temperature for two enzymes 0 20 Optimal pH for pepsin (stomach enzyme) 100 Optimal pH for trypsin Rate of reaction (intestinal enzyme) 4 5 pH (b) Optimal pH for two enzymes 0 1 2 3 6 7 8 9 10 What effects enzyme activity? • Co-factors non-protein helpers for catalytic activity • Co-enzymes are organic co-factors seen mostly in vitamins • Competitive inhibitors reduce enzyme productivity by blocking substrates from entering active sites • Noncompetitive inhibitors they impede enzymatic reactions by binding to another part of the enzyme Fig. 8-19 Substrate Active site Competitive inhibitor Enzyme Noncompetitive inhibitor (a) Normal binding (b) Competitive inhibition (c) Noncompetitive inhibition