Chapter 8: Metabolism

Metabolism Metabolism: The totality of an organisms chemical reactions Manages the material and energy resources of the cell Begin with molecule and end with product Catabolic pathway: Release of energy by breakdown of complex molecules to simpler compounds When digestive enzymes break down food Anabolic pathway: Consume energy to build complex molecules from simpler ones Building muscle fibers from amino acids in response to exorcise

Complexity of Metabolic Pathways

Anabolic vs Catabolic

Energy Energy is the capacity to do work Objects in motion possess kinetic energy Objects at rest possess potential energy Chemical energy: potential energy stored in the form of chemical bonds

Energy Kinetic energy is energy associated with motion Heat (thermal energy) is kinetic energy associated with random movement of atoms or molecules 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

Thermo Dynamics The study of energy transformations that occur in matter Closed systems verses open systems Organisms are open systems The two laws NUMERO UNO: principal of conservation of energy Energy can be transferred and transformed, but it cannot be created or destroyed NUMERO DOS: Every energy transformation or transfer increases the entropy (disorder) of the universe

Thermodynamics During energy transfer energy is often lost in the form of heat, sound, friction, and so on. Think of all the energy lost as a car accelerates

Free Energy Free energy: the part of a systems energy that is able to perform work when the temperature of a system is uniform. EXERgonic reaction: Energy is released Energy is released Occur spontaneously Release free energy into the system ENDERgonic reaction: Requires energy Absorbs free energy from the system

The change in free energy (∆G) during a process is related to the change in enthalpy, or change in total energy (∆H), change in entropy (∆S), and temperature in Kelvin (T): ∆G = ∆H – T∆S Only processes with a negative ∆G are spontaneous Spontaneous processes can be harnessed to perform work Can use the free energy equation to determine if a reaction will occur spontaneously or not Very important when studying metabolism and trying to determine which reactions will happen spontaneously.

Free Energy Free energy measure of a system’s instability, tendency to change to more stable state During a spontaneous change, free energy decreases and stability of system increases Equilibrium: state of max stability A process is spontaneous and can perform work only when it is moving toward equilibrium

Free Energy Changes Processes are spontaneous and can do work only when they are moving toward equilibrium