Chapter 6 - 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

  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. 6.1]

Energy Flow in Chemical Reactions

• some reactions release energy

  • exergonic

• in some reactions, energy input is required

  • endergonic

• you can use an exergonic  reaction to drive an endergonic reaction -energy coupling [Fig. 6.4]

  • cells use ATP [Fig. 6.3]

How to Speed up Reactions

• reduce activation energy [Fig. 6.5]

• catalyst

  • reaction must be spontaneous

  • not consumed

• enzyme

  • biological catalyst

  • how it works [Fig. 6.6]

  • induced fit model [Fig. 6.7]

Factors Affecting Enzymatic Reactions

• substrate concentration

• enzyme concentration

• temperature and pH [Fig. 6.8 & 6.9]

• inhibitors

Overview of Cellular Metabolism

• metabolism:

• energy can be stored during photosynthesis

  • endergonic

  • equation

  • energy is sunlight

• stored energy can be released during cellular respiration

  • exergonic

  • equation

  • energy is ATP

• both reactions make ATP using electron transport system

  • energy from high energy electrons are used to do work

  • work: pumping protons from one side of a membrane to another

  • protons are used to generate ATP

© Carol L. Wymer, 2004