Download The Laws of Thermodynamics and more Study notes Biology in PDF only on Docsity! The Laws of Thermodynamics Thermodynamics - The study of energy transfers that occur in molecules or collections of molecules > System - Particular item that weโre interested in - E.g. cell and ecosystem > Surroundings - Everything that is not included in the system * The system and the surroundings together make up the universe. Three Types of Systems in Thermodynamics > Open system - A system that can exchange both energy and matter with its surroundings > Closed system - A system that can exchange only energy with its surroundings > Isolated system - A system that cannot exchange either matter or energy with its surroundings The First Law of Thermodynamics โ Energy cannot be created or destroyed; it can only be converted from one form to another. Examples: 1. Light bulbs transform electrical energy into light energy (radiant energy). 2. One pool ball hits another, transferring kinetic energy and making the second ball move. 3. Plants convert energy of sunlight (radiant energy) into chemical energy stored in organic molecules. 4. People transform chemical energy from their last snack into kinetic energy as they walk and breathe. * Starting energy is released as thermal energy (heat). The Second Law of Thermodynamics โ Energy cannot be created or destroyed but it can change from more-useful forms into less-useful forms. - Every time an energy transfer happens, some amount of useful energy will move from useful to the useless category. In most cases, this unusable energy takes the form of heat. โ Every energy transfer that takes place will increase the entropy of the universe and reduce the amount of usable energy available to do work. > Entropy - Degree of randomness or disorder in a system *The high degree of organization of living things is maintained by a constant input of energy, and is offset by an increase in the entropy of the surroundings. Metabolism Metabolism - All of the chemical reactions that take place inside of a cell Two Metabolic Processes that are Crucial to Life on Earth > Breaking down glucose: Cellular Respiration - The process of cells getting energy from glucose (๐ถโ๐ปโโ๐โ) - During the process, a glucose molecule is broken down gradually to release energy in the form of adenosine triphosphate or ATP *ATP, also known as the โenergy currencyโ of the cell, is a small molecule that gives cells a convenient way of briefly storing energy. - The process has an overall reaction of: ๐ถโ๐ปโโ๐โ + 6๐โ โ 6๐ถ๐โ + 6๐ปโ๐ + ๐๐๐๐๐๐ฆ > Building up glucose: Photosynthesis - The process of plants using the energy of sunlight to convert carbon dioxide gas into sugar molecules or glucose (๐ถโ๐ปโโ๐โ) - The process has an overall reaction of the cellular respiration flipped backwards: 6๐ถ๐โ + 6๐ปโ๐ + ๐๐๐๐๐๐ฆ โ ๐ถโ๐ปโโ๐โ + 6๐โ Metabolic Pathway - A series of connected chemical reactions that feed one another > Anabolic pathways - Build complex molecules from simple ones and typically need an input of energy - E.g. building glucose from carbon dioxide, synthesis of proteins from amino acids > Catabolic pathways - Breakdown of complex molecules into simpler ones and typically release energy - Energy stored in the bonds of complex molecules, such as glucose and fats, is released in this pathway and will then be harvested in forms that can power the work of the cell - E.g. synthesis of ATP *The chemical reaction in metabolic pathways donโt take place automatically without guidance as each reaction step in a pathway is facilitated, or catalyzed, by a protein called an enzyme. ATP and Reaction Coupling ATP Structure
