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. Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.

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 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. Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College. Look

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 Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College. RELEASE ENERGY ABSORB ENERGY

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. 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. 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. Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College. This symbol means the difference in Enthalpy.

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 ∆ H˚. Standard states are at 25˚ C and 1 atm of pressure. 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.

More simply put: 2+2=4 is the same as =4

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 J/g·Cº. This means that J of heat is needed is needed to raise 1 gram of water 1ºC. 1calorie= J 1000calories=1 kilocalorie or CAL.

Kilocalories are used in nutrition. Calorimeters are used to figure out the calories in food sources. 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 fat and sugar. C 6 H 12 O 6 (s) + 6 O 2 (g)  6 CO 2 (g) + 6 H 2 O (l)  H  = kJ Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College. EXOTHERMIC

C 57 H 110 O 6 (s) + 163/2 O 2 (g)  57 CO 2 (g) + 55 H 2 O (l).  r H  = x 10 4 kJ Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College. EXOTHERMIC Twice the energy as proteins and glucose!

Fuels and O2 Catabolism ATP Cellular Processes Anabolism water ADP CO 2 P IN SUMMARY!!! Life Sciences-HHMI Outreach. Copyright 2009 President and Fellows of Harvard College.