Biology 1201 Exam 2 Material Chapter 8 Chemical Reactions Pages 142 161 I Chemical Reactions When two or more atoms ions or molecules collide in such a way that they produce a new substance They must physically hit each other hard enough to form something new All chemical reactions are governed by the following laws 1st Energy can neither be created nor destroyed only converted from one form to another 2nd When converting energy from one form to another the amount of useful energy decreases Types of Chemical Reactions Spontaneous versus Non Spontaneous Spontaneous reaction Release free energy Greater reactants than products Can occur without outside help Exergonic Non spontaneous reaction Require free energy Needs outside help or else it cannot occur Endergonic Less reactants than products Free Energy G Energy that is free and available to do useful work in the cell In all spontaneous reactions G free energy in systems decreases exergonic In all non spontaneous reactions G increases endergonic o Exergonic releases free energy o Endergonic requires free energy Equation G H T S G Free Energy H enthalpy the heat energy of the system contained within the system T Temperature Kelvins S entropy a measure of disorder in a system greater disorder greater entropy What happened during the reaction match and flame experiment Biology 1201 Exam 2 Material Heat energy was released Entropy decreased X Entropy increased enthalpy decreased More than one of the above X It was non spontaneous X Spontaneous High Activation Energy The free energy increased X The Free energy decreased What happened during this reaction solution mixed in and beaker got cold G H T S G decreased H increased because Heat was not released T decreased S increased Heat energy was released X Heat energy was absorbed Entropy increased Disorder increased Spontaneous Free energy increased X Enthalpy increased Free energy decreased o It can t be spontaneous and have free energy More than one of the above Which of the following reactions will always be spontaneous Enthalpy increases entropy decreases Enthalpy decreases entropy decreases Enthalpy increases entropy increases Enthalpy decreases entropy increases G H T S G decreases then H decreases Which of the following will always be a non spontaneous reaction Enthalpy increases entropy decreases Enthalpy decreases entropy decreases Enthalpy increases entropy increases Enthalpy decreases entropy increases A spontaneous reactions occurring at 100 Kelvins and with a 250 Kcal increase in enthalpy it must have which of the following change in entropy 3 5 Kcal G H T S G Free energy decreases H increases S increases A non spontaneous reaction occurring at 200k with a 150Kcal decrease in enthalpy has which of the following changes in entropy 1 0Kcal In a non spontaneous reaction free energy will be required positive free energy increase Biology 1201 Exam 2 Material A spontaneous reaction occurring at 200k with a 1 5kcal decrease in entropy has which of the following changes in enthalpy 400Kcal G will be negative Temp 200k S 1 5Kcal Enthalpy will be negative G H 200K 1 5Kcal G will be positive H will be negative G 150Kcal 200K S T 200k II Living vs Non living Systems i Nonliving Systems ii Living Systems a Less organized b Low energy c Very slow a More organized b High energy c Fast How do living things accomplish this External Energy source Living things require an external energy source for chemical reactions to occur The sun is the main external source for living things Speed Organic Catalysts Enzymes III Enzymes Almost all are proteins NOT all of them They are large globular proteins that contain primary secondary and tertiary structure o They may even have quaternary structure Function i Organic Catalysts Speed up the rate of a reaction but not used up during the reaction Very specific Using the Diagram Which line represents the activation energy for an uncatalysed reaction Which represents the change in free energy Which represents the activation energy for a catalyzed reaction Biology 1201 Exam 2 Material Induced Fit Model The substrate binds to the active site of the enzyme This alters the shape of the enzyme which is made up weak bonds allows for change Creating or induces a fit that promotes the reaction lowers the activation energy o Example Using a baseball mitt to catch a baseball squeeze the glove What do the following have in common They are enzyme inhibitors which means they regulate enzymes Roundup Glyphosate Anti bacterial hand soap Triclosan Aleve Naproxen Sodium Viagra Sildenafil a Competitive Inhibition Inhibitor binds to the active site and blocks access to the active site Some competitive inhibitors are removable and some are irreversible Example toxins can be irreversible b Noncompetitive Inhibition Inhibitor binds to a site other than the active site and alters the shape of the active site The active site cannot fit the substrate c Allosteric Inhibition Regulation Enzyme alternates between active and inactive forms Inhibitor binds to a site other than the active site and stabilizes one shape of the enzyme inactive site Chapter 7 Membrane Structure and Function Pages 125 141 IV Cells the minimum organization of living matter a Fluid Mosaic Model Phospholipid bilayer with a mosaic of associated proteins The interior is nonpolar Biology 1201 Exam 2 Material The exterior is polar The heads are hydrophilic The tails are hydrophobic Clicker Questions What is more likely to happen Is it easier for adjacent heads to switch spots or for opposite heads tails to switch spots on phospholipids It is easier for adjacent heads to switch places so that the hydrophobic tails do not come in contact with water Adjacent heads will often switch places in systems The section of the integral protein that is within the phospholipid bilayer contains what kind of amino acids Nonpolar The peripheral protein contains what kind of amino acids Polar amino acids Cell Coat Outside of cell membrane Composition o Glycolipids attached to lipids heads o Glycoproteins attached to proteins peripheral Function o Cell recognition Why do cells have membranes 1 Structure 2 Function o Maintain concentrations of molecules and ions o Create free energy gradients The greater the difference the greater the concentration gradient o Orient molecules into functional complexes V Membrane Permeability what effects what can pass through the bilayer o Size and shape of molecules o Solubility in lipids o Net electric
View Full Document
Unlocking...