Summer 2009 Workshop in Biology and Multimedia for High School Teachers Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College • Energy is a critical part of your everyday life • Energy is either released or absorbed in a chemical reaction This occurs when the bonds between the atoms are broken and then the atoms rearranged • The food you eat is the fuel which will provide the energy you need to sustain life http://en.wikipedia.org/wiki/File:MyPyramidFood.svg Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College http://en.wikipedia.org/wiki/Carbon Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College Reactions that absorb energy are called Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College Reactions that release energy are called http://en.wikipedia.org/wiki/File:ThermiteFe2O3.JPG Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College Digestion is the physical and chemical processes used to break down food into smaller molecules that can be absorbed by the human body http://en.wikipedia.org/wiki/File:Macaca_arctoides.pn g http://www.whfoods.com/genpage.php?tname=faq&dbid=16 Look Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College RELEASE ENERGY Metabolism refers to all the chemical reactions within an organism that breakdown molecules to release energy and all the reactions that use energy to build complex molecules These reactions are referred to as ABSORB ENERGY Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College http://en.wikipedia.org/wiki/File:Animal_mitochondrion_diagram_en_%28edit%29.svg When we speak of energy we are talking … Catabolism is the process where larger molecules are broken down into smaller molecules releasing energy The molecules are broken down into either simple sugars, glycerol and fatty acids or amino acids This process is exothermic http://commons.wikimedia.org/wiki/File:Catabolism.svg http://commons.wikimedia.org/wiki/File:FlameV1.png Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College Anabolism is the process where smaller molecules are combined to form larger more complex molecules This process requires energy so it is considered an endothermic reaction http://commons.wikimedia.org/wiki/File:Peptidbinding.svg Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College The change in energy is measured in terms of heat The amount of energy (heat) that is contained within the bonds of the reactants is compared to the amount of energy (heat) that is contained within the bonds of the products This is referred to as the H This symbol means the difference in Enthalpy Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College ENTHALPY • Endothermic reactions always have a positive H • Exothermic reactions always have a negative H Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College • Enthalpy changes that are measured when reactants are in their standard states are called STANDARD ENTHALPY CHANGES • STANDARD ENTHALPIES are denoted by states are at 25˚ C and atm of pressure ∆ H˚ Standard • The enthalpy change in a reaction is directly related to the amount of reactants Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College Hess’s Law states that if a series of reactions are added together, the enthalpy change for the net reaction is the same as the sum of the individual reactions Huh? More simply put: 2+2=4 is the same as 1+1+1+1=4 Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College • The subject of calorimetry studies the flow of heat and heat measurements • Every object has the ability to absorb heat The amount of heat that is absorbed is referred to as the heat capacity • The heat capacity is the amount of heat required to raise the temperature by 1˚C • The heat capacity depends on the composition and the amount of the substance, Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College The heat capacity of one gram of a substance is referred to as the SPECIFIC HEAT Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College The specific heat of water is 4.184 J/g·Cº This means that 4.184 J of heat is needed is needed to raise gram of water 1ºC 1calorie= 4.184 J 1000calories=1 kilocalorie or CAL http://en.wikipedia.org/wiki/File:Thermometer_CF.svg Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College • Kilocalories are used in nutrition • Calorimeters are used to figure out the calories in food sources https://vinstan.wikispaces.com/file/view/calorimeter.PNG http://en.wikipedia.org/wiki/File:Nutrition_label gif Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College • The catabolism of food is an oxidative reaction • Most of our energy comes from Calories found in • C H O (s) + O (g) → CO (g) + H O (l) 12 2 fat and sugar ∆H° = -2816 kJ EXOTHERMI C Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College C57H110O6 (s) + 163/2 O2 (g) → 57 CO2 (g) + 55 H2O (l) ∆rH° = -37.8 x 104 kJ EXOTHERMIC Twice the energy as proteins and glucose! Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College Catabolism Fuels and O2 CO2 water ATP ADP P Cellular Processes Anabolism IN SUMMARY!!! Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College Life Sciences-HHMI Outreach Copyright 2009 President and Fellows of Harvard College  ... President and Fellows of Harvard College RELEASE ENERGY Metabolism refers to all the chemical reactions within an organism that breakdown molecules to release energy and all the reactions that use energy. .. atoms are broken and then the atoms rearranged • The food you eat is the fuel which will provide the energy you need to sustain life http://en.wikipedia.org/wiki/File:MyPyramidFood.svg Life Sciences-HHMI... Copyright 2009 President and Fellows of Harvard College • Enthalpy changes that are measured when reactants are in their standard states are called STANDARD ENTHALPY CHANGES • STANDARD ENTHALPIES are