Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings PowerPoint ® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Chapter 8 An Introduction to Metabolism

Essential knowledge 2.A.1: All living systems require constant input of free energy. A. Life requires a highly ordered system. 1. Order is maintained by constant free energy input into the system. 2. Living systems require energy for maintaining homeostasis. 3. Loss of order or free energy flow results in death.

Energy: Matter: Order vs. Disorder

Concept 8.1: An organism’s metabolism transforms matter and energy, subject to the laws of thermodynamics Metabolism: the sum total of an organisms chemical reactions – Includes rearrangements of matter and use of energy to help the organism maintain homeostasis, growth and reproduction. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Organization of the Chemistry of Life into Metabolic Pathways A metabolic pathway begins with a specific molecule and ends with a product Each step is catalyzed by a specific enzyme Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Enzyme 1Enzyme 2Enzyme 3 D CB A Reaction 1Reaction 3Reaction 2 Starting molecule Product

Catabolic pathways: release energy, increase disorder by breaking down complex molecules into simpler compounds Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Anabolic pathways: Use energy to increase order/ complexity Two Basic Types of Metabolic Pathways

Forms of Energy Energy is the capacity to cause change/do work Ordered/ concentrated forms of energy can perform more change/ work Less concentrated energy can do little work – Heat is considered less ordered/ concentrated energy Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

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 can be converted from one form to another Animation: Energy Concepts Animation: Energy Concepts Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Forms of Energy

Fig. 8-2 Climbing up converts the kinetic energy of muscle movement to potential energy. A diver has less potential energy in the water than on the platform. Diving converts potential energy to kinetic energy. A diver has more potential energy on the platform than in the water.

Metabolism: cycles of matter and flow of energy Matter is cycled within and between organisms and their environment Energy flows through non-living and living systems. – It can be temporarily stored or transformed into less concentrated forms of energy, always decreasing with each transformation.

The Laws of Energy Transformation Thermodynamics is the study of energy transformations A closed system: does not exchange matter or energy with its surroundings In an open system: can exchange matter and energy with the surroundings Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Organisms are open systems Matter Cycles Energy Flows

The 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 1 st law: Law of conservation of energy Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Second Law of Thermodynamics During every energy transfer or transformation, some energy is lost as heat According to the second law of thermodynamics : – Every energy transfer or transformation increases the entropy (disorder) of the universe Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Fig. 8-3 (a) First law of thermodynamics (b) Second law of thermodynamics Chemical energy Heat CO 2 H2OH2O +

Living systems convert organized forms of energy to heat Spontaneous processes occur without energy input; they can happen quickly or slowly For a process to occur without energy input, it must increase the entropy (disorder) of the universe Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

How is diffusion and osmosis an example of increasing the entropy of the universe and thus a spontaneous process?

How do cells take advantage of the 2 nd law of thermodynamics (disorder of the universe is always increasing) to obtain nutrients and get rid of wastes? CO 2 C 6 H 12 O 6

How can you use the 2 nd law of thermodynamics as an excuse for your messy room?