Bio 110 Exam #2
Chapter 5
The Working Cell
Energy
• Capacity to do work
• Types of energy
–
–
–
–
Kinetic energy – energy of motion
Potential energy – stored energy
Thermal energy - heat
Chemical energy - potential energy of molecules
• Thermodynamics
– Study of energy
Oxidation-Reduction Reactions
• When an atom or molecule loses an electron, it is said to be oxidized – process called oxidation
• When an atom or molecule gains an electron, it is said to be reduced – process called reduction
• Oxidation and reduction always take place together • Reduced molecule has more energy than oxidized molecule • Energy associated with electron and distance from nucleus Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Loss of electron (oxidation) o A
e–
o
B
A
B
A*
Gain of electron (reduction)
Low energy
High energy
–
+
B*
First Law of Thermodynamics
• Energy cannot be created or destroyed
• It can only change from one from another
– Kinetic ↔ potential
• Total amount of energy remains the same
Second Law of Thermodynamics
• Energy conversions are not 100% efficient
• Energy flows from high energy forms to forms lower in energy
– This process is referred to as disorder
• Disorder in the universe is continuously increasing • Entropy is a measure of disorder in a system
• Entropy increases
Energy Gained
Energy Lost
With each conversion, there is a one-way flow of energy back to the environment
Sunlight energy reaches
Earth. Producers secure some and convert it to stored forms of energy. They and all other organisms convert stored energy to forms that can do cellular work.
Energy Lost
Free Energy
• It takes energy to break chemical bonds
• Free energy – energy available to do work in any system • Endergonic reactions
– Products contain more free energy than reactants
– Do not proceed spontaneously
– Require input of
The Working Cell
Energy
• Capacity to do work
• Types of energy
–
–
–
–
Kinetic energy – energy of motion
Potential energy – stored energy
Thermal energy - heat
Chemical energy - potential energy of molecules
• Thermodynamics
– Study of energy
Oxidation-Reduction Reactions
• When an atom or molecule loses an electron, it is said to be oxidized – process called oxidation
• When an atom or molecule gains an electron, it is said to be reduced – process called reduction
• Oxidation and reduction always take place together • Reduced molecule has more energy than oxidized molecule • Energy associated with electron and distance from nucleus Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Loss of electron (oxidation) o A
e–
o
B
A
B
A*
Gain of electron (reduction)
Low energy
High energy
–
+
B*
First Law of Thermodynamics
• Energy cannot be created or destroyed
• It can only change from one from another
– Kinetic ↔ potential
• Total amount of energy remains the same
Second Law of Thermodynamics
• Energy conversions are not 100% efficient
• Energy flows from high energy forms to forms lower in energy
– This process is referred to as disorder
• Disorder in the universe is continuously increasing • Entropy is a measure of disorder in a system
• Entropy increases
Energy Gained
Energy Lost
With each conversion, there is a one-way flow of energy back to the environment
Sunlight energy reaches
Earth. Producers secure some and convert it to stored forms of energy. They and all other organisms convert stored energy to forms that can do cellular work.
Energy Lost
Free Energy
• It takes energy to break chemical bonds
• Free energy – energy available to do work in any system • Endergonic reactions
– Products contain more free energy than reactants
– Do not proceed spontaneously
– Require input of