Chapter 5 - Energy and Metabolism

Energy

• def.: capacity to do work

• forms of energy

  1. potential energy - stored energy

  2. kinetic energy - energy of movement

• need to know: the quantity of energy and its usefulness

• Laws of Thermodynamics

  1. 1st Law - the amount of energy in the universe is constant [Fig. 5.3]

  2. 2nd Law - when energy is converted from one form to another, the amount of useful energy decreases (disorder increases)

• one way flow of energy in living systems [Fig. 5.4]

Energy Flow in Chemical Reactions

• some reactions release energy

  • exergonic [Fig. 5.5]

• in some reactions, energy input is required

  • endergonic [Fig. 5.5]

• you can use an exergonic  reaction to drive an endergonic reaction -energy coupling

  • cells use ATP [Fig. 5.6]

How to Speed up Reactions

• reduce activation energy [Fig. 5.12]

• enzyme

  • biological catalyst

  • how it works [Fig. 5.13]

© Carol L. Wymer, 2003