LEQ: What is the role of ATP in cellular activities? Cellular Energy Pages 72 to 75

Energy What is energy? What is Kinetic 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

Climbing up converts the kinetic energy of muscle movement to potential energy. A diver has less potential energy in the water than on the platform. Diving converts potential energy to kinetic energy. A diver has more potential energy on the platform than in the water.

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

(a) First law of thermodynamics (b) Second law of thermodynamics Heat Chemical energy Heat CO2 H2O +

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

Progress of the reaction Fig. 8-6b Products Amount of energy required (∆G > 0) Energy Free energy Reactants Figure 8.6b Free energy changes (ΔG) in exergonic and endergonic reactions 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

Progress of the reaction Fig. 8-6a Reactants Amount of energy released (∆G < 0) Free energy Energy Products Figure 8.6a Free energy changes (ΔG) in exergonic and endergonic reactions 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 Phosphate groups Ribose Adenine

H2O P P P Adenosine triphosphate (ATP) P + P P + Energy Fig. 8-9 P P P Adenosine triphosphate (ATP) H2O Figure 8.9 The hydrolysis of ATP P + P P + Energy i Inorganic phosphate Adenosine diphosphate (ADP)

ATP – ADP Cycle H2O Energy for cellular work (endergonic, + Energy from catabolism (exergonic, energy-releasing processes) Energy for cellular work (endergonic, energy-consuming ATP H2O Phosphorylation - adding a phosphate

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 Solute Solute transported i Vesicle (a) Transport work: ATP phosphorylates transport proteins ADP ATP + P i Vesicle Cytoskeletal track Figure 8.11 How ATP drives transport and mechanical work ATP Motor protein Protein moved (b) Mechanical work: ATP binds noncovalently to motor proteins, then is hydrolyzed