Energy Chapter 8 PDF

Kinetic energy is energy associated with motion Thermal energy is the kinetic energy associated with random movement of atoms or molecules Heat is thermal energy in transfer between objects Potential energy is energy that matter possesses because of its location or structure Chemical...

Kinetic energy is energy associated with motion Thermal energy is the kinetic energy associated with random movement of atoms or molecules Heat is thermal energy in transfer between objects Potential energy is energy that matter possesses because of its location or structure Chemical energy is potential energy available for release in a chemical reaction Energy can be converted from one form to another © 2017 Pearson Education, Inc. Figure 8.2 A diver has more potential Diving converts energy on the platform potential energy to than in the water. kinetic energy. Loading… Climbing up converts the kinetic A diver has less potential energy of muscle movement energy in the water to potential energy. than on the platform. © 2017 Pearson Education, Inc. Animation: Energy Concepts © 2017 Pearson Education, Inc. he Laws of Energy Transformation Thermodynamics is the study of energy transformations An isolated system, such as that approximated by liquid in a thermos, is unable to exchange energy or matter with its surroundings In an open system, energy and matter can be transferred between the system and its surroundings Organisms are open systems © 2017 Pearson Education, Inc. he 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 © 2017 Pearson Education, Inc. Figure 8.3 Hea CO t 2 + Chemica H2 l Kineti O energy c in food energy (a) First law of thermodynamics (b) Second law of thermodynamics Energy can be transferred and Every energy transfer or transformed, but it transformation increases the cannot be created or destroyed © 2017 Pearson Education, Inc. he 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 of the universe Entropy is a measure of molecular disorder, or randomness © 2017 Pearson Education, Inc. Figure 8.3b Hea t CO 2 + H2 Kinetic O energy (b) Second law of thermodynamics © 2017 Pearson Education, Inc.  Living cells unavoidably convert organized forms of energy to heat, a more disordered form of energy Spontaneous processes occur without energy input; they can happen quickly or slowly For a process to occur spontaneously, it must increase the entropy of the universe Processes that decrease entropy are nonspontaneous; they will occur only if energy is provided © 2017 Pearson Education, Inc. Biological Order and Disorder Organisms create ordered structures from less organized forms of energy and matter Organisms also replace ordered forms of matter and energy in their surroundings with less ordered forms For example, animals consume complex molecules in their food and release smaller, lower energy molecules and heat into the surroundings © 2017 Pearson Education, Inc. Concept 8.3: ATP powers cellular work by coupling exergonic reactions to endergonic reactions An exergonic reaction proceeds with a net release of free energy and is spontaneous An endergonic reaction absorbs free energy from its surroundings and is nonspontaneous A cell does three main kinds of work: Chemical work—pushing endergonic reactions Transport work—pumping substances against the direction of spontaneous movement Mechanical work—such as contraction of muscle cells © 2017 Pearson Education, Inc.  To do work, cells manage energy resources by energy coupling, the use of an exergonic process to drive an endergonic one Most energy coupling in cells is mediated by ATP © 2017 Pearson Education, Inc. he Structure and Hydrolysis of ATP ATP (adenosine triphosphate) is the cell’s energy shuttle ATP is composed of ribose (a sugar), adenine (a nitrogenous base), and three phosphate groups © 2017 Pearson Education, Inc. Figure 8.9 Adenine Triphosphate group Ribose (3 phosphate groups) (a) The structure of ATP P P P Adenosine triphosphate (ATP) H2 O P P P Energ i y Adenosine Inorganic diphosphate (ADP) phosphate (b) The hydrolysis of ATP © 2017 Pearson Education, Inc.  The bonds between the phosphate groups of ATP’s tail can be broken by hydrolysis Energy is released from ATP when the terminal phosphate bond is broken This release of energy comes from the chemical change to a state of lower free energy, not from the phosphate bonds themselves © 2017 Pearson Education, Inc. Figure 8.9b P P P Adenosine triphosphate (ATP) H2 O P P P Energy i Adenosine Inorganic diphosphate (ADP) phosphate (b) The hydrolysis of ATP © 2017 Pearson Education, Inc. How the Hydrolysis of ATP Performs Work The three types of cellular work (mechanical, transport, and chemical) are powered by the hydrolysis of ATP In the cell, the energy from the exergonic reaction of ATP hydrolysis can be used to drive an endergonic reaction Overall, the coupled reactions are exergonic © 2017 Pearson Education, Inc.  ATP drives endergonic reactions by phosphorylation, transferring a phosphate group to some other molecule, such as a reactant The recipient molecule is now called a phosphorylated intermediate © 2017 Pearson Education, Inc.