Energy

1
Energy

• Chapter 6
• p. 119-128

2
Energy Is Everywhere

• All life on Earth depends on energy from the sun
• Suns energy is not rechargeable
• Living things convert energy to a usable form

3
Defining Energy

• Capacity to do work
• Capacity to bring movement against an opposing
  force
• Present although it cant be seen or grasped

4
Forms of Energy

• Potential
• Stored energy
• Example ball at rest

5
Forms of Energy

• Kinetic
• Energy in motion
• Example ball rolling, falling off table

6
Thermodynamics

• Study of energy
• Originated when better steam engine needed
• Helped begin Industrial Revolution

7
Laws of Thermodynamics

• First Law
• Energy cannot be created or destroyed
• Energy can only be transformed
• Excess unused energy is released as heat

8
Laws of Thermodynamics

• Second Law
• Energy release results in greater disorder
• Atoms change from structured, organized
  arrangement to less-ordered to release energy

9
Why dont we burn up?

• Laws of Thermodynamics state that disorder
  increases in the universe as energy is released
  in the form of heat.
• We dont burn up because we can build up and
  store energy for life processes.

10
Types of Reactions

• Exergonic- breaking down reaction, reactants have
  more energy than products
• Example starches to individual sugars

11
Types of Reactions

• Endergonic- building-up reaction, products have
  more energy than reactants
• Example glucose to glycogen

12
Glucose to Glycogen
13
Coupled Reactions

• Endergonic and exergonic reactions work together
• Exergonic (energy-releasing) reactions power
  endergonic (energy-consuming) reactions

14
The Main Energy Molecule ATP
ATP Adenosine Triphosphate
15
The Main Energy Molecule

• Three phosphates contain stored energy
• Energy is released as phosphates are broken off
• Energy used for reactions and cellular functions

16
ATP as Money
17
Why dont these reactions take longer?

• Enzymes- proteins that speed up chemical
  reactions
• Extremely important because no living thing could
  functions without them
• Each enzyme is specific for a different function

18
How Enzymes Work
19
Metabolism

• Metabolism- the sum of all the chemical reactions
  in an organism
• Metabolic pathway- a set of steps controlled by
  enzymes to make a specific product
• Like an assembly line where every enzyme has a
  job to do before the next piece can be assembled

20
A Very Complicated Metabolic Pathway!
21
How do enzymes relate to energy?

• Enzymes decrease the amount of energy needed to
  allow a reaction to proceed, known as activation
  energy.

22
Enzymes at Work
23
How do enzymes relate to energy?

• Enzymes are catalysts, meaning that they are not
  changed during a reaction and can be reused.