LEQ: What is the role of ATP in cellular activities? Cellular Energy Pages 72 to 75 Energy What is energy? ◦ The capacity to do work What is Kinetic energy? ◦ Energy of motion ◦ Heat (thermal energy) is kinetic energy given off due the the movement of molecules What is Potential energy? ◦ Stored energy that an object possess as a result of its location or structure ◦ Chemical energy is potential energy available for release in a chemical reaction A diver has more potential energy on the platform than in the water. Diving converts potential energy to kinetic energy. Climbing up converts the kinetic A diver has less potential energy of muscle movement energy in the water than on the platform. to potential energy. Thermodynamics What is thermodynamics? ◦ The study of energy transformation ◦ Organisms are open systems ◦ In an open system, energy and matter can be transferred between the system and its environment The First Law of Thermodynamics According to the first law of thermodynamics, the energy of the universe is constant: – Energy can be transferred and transformed, but it cannot be created or destroyed The first law is also called the principle of conservation of energy The Second Law of Thermodynamics During every energy transfer or transformation, some energy is unusable, and is often lost as heat According to the second law of thermodynamics: – Every energy transfer or transformation increases the entropy (disorder) of the universe Heat Chemical energy (a) First law of thermodynamics CO2 + H2O (b) Second law of thermodynamics Biological Order and Disorder Living things are ordered, decreasing entropy - this requires an input of energy, increasing entropy…. ◦ Building macromolecules (dehydration synthesis) decreases entropy by organizing atoms into molecules, molecules into cells, etc… ◦ In order to build / maintain organization requires an input of energy which increases entropy Chemical Reactions Endergonic Reactions ◦ ◦ ◦ ◦ “Energy In” Require a net input of energy Rich in potential energy Photosynthesis – takes in energy to produce sugar; energy stored in bonds Fig. 8-6b Free energy Products Amount of energy required (∆G > 0) Energy Reactants Progress of the reaction (b) Endergonic reaction: energy required Chemical Reactions Exergonic Reactions ◦ “Energy Out” ◦ Chemical reactions that release energy ◦ Cellular respiration – breaking bonds of sugar to release energy Fig. 8-6a Free energy Reactants Amount of energy released (∆G < 0) Energy Products Progress of the reaction (a) Exergonic reaction: energy released Chemical Reactions Cellular Metabolism ◦ Sum of all exergonic and endergonic reactions in a cell ◦ Anabolic Pathways – consume energy to build complex molecules from simple ones (endergonic) ◦ Catabolic Pathways – release energy by breaking down complex molecules into simple ones (exergonic) Chemical Reactions Energy Coupling ◦ The use of energy released from exergonic reactions to drive essential endergonic reactions Adenosine Triphosphate Energy currency of the cell Powers nearly all cellular work through energy coupling reactions Adenine Phosphate groups Ribose Fig. 8-9 P P P Adenosine triphosphate (ATP) H2O Pi + Inorganic phosphate P P + Adenosine diphosphate (ADP) Energy ATP – ADP Cycle ATP + H2O Energy from catabolism (exergonic, energy-releasing processes) Phosphorylation - adding a phosphate ADP + P i Energy for cellular work (endergonic, energy-consuming processes) Cells use ATP Three types of cellular work that are powered by hydrolysis of ATP ◦ Cell Transport – Bringing materials into cells ◦ Mechanical Work – muscle contractions ◦ Chemical Work – macromolecule synthesis Fig. 8-11 Membrane protein P Solute Pi Solute transported (a) Transport work: ATP phosphorylates transport proteins ADP + ATP P Vesicle Cytoskeletal track ATP Motor protein Protein moved (b) Mechanical work: ATP binds noncovalently to motor proteins, then is hydrolyzed i