Metabolism: Energy and Enzymes By: Holly Davis and Diana Brizan

Energy: the ability to do work or bring about change. Develop, grow and reproduce.  There are many different types of energy  Kinetic is energy of motion (a ball rolling)  Mechanical is also a ball rolling or muscle contracting  Solar energy is energy from the sun  Potential is stored energy (food we eat)  Chemical energy (organic molecules)

Laws of Thermodynamics 1.The law of conservation of energy. Energy cannot be created or destroyed, but it can be changed from one form to another. 2. Second Law Energy cannot be changed from one form to another without a loss of usable energy.

 Entropy: measures relative amount of disorder or randomness.  Every process in cells increases total entropy, making less energy available to do work in the future.  Eventually all usable forms of energy become heat. Heat cannot be converted to any other form of energy.

Metabolic Reaction  Metabolism - sum of all chemical reactions that occur in a cell  Reactants – substances that participate in reaction  Products – substances that are formed as a result of reaction A + B  AB Product A and B Join to form the reactant AB

 A spontaneous reaction increases total entropy.  Free energy “G” – amount of energy still free after a chemical reaction has taken place.  Exergonic reactions – product has less free energy then reactants  Endergonic reactions – product has more free energy then reaction, they can only occur if there is an input of energy. Endergonic reaction

ATP (adenosine triphosphate)  Carrier of energy  Common energy currency, can be used in many different types of reactions  ATP is constantly being made from ADP (adenosine diphosphate) and Phosphate, little energy is wasted blue – ribose (5 carbon sugar) Green - adenine (a nitrogenous base) Yellow – phosphate groups  Coupled Reaction : when the energy released from an exergonic reaction is used to drive an endergonic reaction

Metabolic Pathways & Enzymes  Enzyme is a protein molecule that functions as an organic catalyst to speed chemical reaction  Reactants in enzymatic reaction are called substrates for that enzyme  Reactions in cells occur usually because they are part of a metabolic pathway, series of linked reactions.

Enzyme Substrate Complex  One part of the enzyme is called the active site, which complexes with the substrate.  Fit together like “key and lock”. Induced Fit Model means that it undergoes slight change for optimum fit.  Every reaction requires its specific enzyme its specific enzyme

Factors Affecting Enzymatic Speed Substrate Concentration: Enzyme activity increases as concentration increases. When all active sites filled, max rate, cannot increase any more Temperature and pH: Higher temperature increases enzyme activity. KMT, higher collision between enzyme and substrate. Too hot becomes denatured. At optimal pH the reaction is highest. Extreme conditions of pH also denatures the enzyme Enzyme Concentration: If there are too many enzymes present they can get in the way. Only certain enzymes work for certain substrates. Enzyme Inhibition: when an active enzyme is prevented from combining with its substrate, eg. poisons.

Oxidation-Reduction  Oxidation – the loss of electrons  Reduction – gain of electrons  Example: Na + Cl  NaCl sodium has been oxidized, chlorine has been reduced  When oxidation and reduction go hand in hand it is called a redox reaction This is an example of a spontaneous redox reaction. When zinc metal is placed in a solution of copper sulfate, the copper is reduced and appears as a black coating on the zinc.

Photosynthesis and cellular respiration permit a Flow of Energy from the sun through all living things Photosynthesis: energy + carbon dioxcide + water  glucose + oxygen Chloroplasts capture solar energy and convert it into ATP Cellular Respiration: Glucose + oxygen  carbon dioxcide + water + energy When ATP is used up as an energy source, all useable energy is converted into heat

Bibliography  Inquiry Into Life ~ Slyvia S. Mader   science.ca/energy_flow/images/kinetic_energy1.png  ckkey.gif  atp_1.GIF  ml   emrxn/sponoxred.jpg