biology sylvia s. mader michael windelspecht chapter 6 metabolism: energy and enzymes lecture...
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BiologySylvia S. Mader
Michael Windelspecht
Chapter 6 Metabolism: Energy and Enzymes
Lecture Outline
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6.1 Cells and the Flow of Energy
• Energy – The ability to do work or bring about a change
Kinetic energy
• Energy of motion
• Mechanical
Potential energy
• Stored energy
• Chemical energy
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Flow of Energy
3
solarenergy
heat
heat
heat
heat
Mechanical energy
Chemicalenergy
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Two Laws of Thermodynamics
• First law: Law of conservation of energy
Energy cannot be created or destroyed, but can be changed from one form to another
• Second law: Law of entropy
When energy is changed from one form to another, there is a loss of usable energy
Waste energy goes to increase disorder
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sun
CO2
H2O
solar energy producer
carbohydrate
heat
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Carbohydrate Metabolism
6
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carbohydrate uncontracted muscle contracted muscle
heat
Cells and Entropy
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H+
H2O
C6H12O6
• more organized• more potential energy• less stable (entropy)
a.
Carbon dioxideand water
• less organized• less potential energy• more stable (entropy)
CO2
kineticenergy
channel protein
H+
H+
H+
H+
H+
H+
H+
H+H+
H+
H+
Unequal distributionof hydrogen ions
Equal distributionof hydrogen ions
• more organized• more potential energy
b.• less stable (entropy)
• less organized• less potential energy• more stable (entropy)
Glucose
H+
H+
H+H+
H+
H+
6.2 Metabolic Reactions and Energy Transformations
• Metabolism Sum of cellular chemical reactions in cell
Reactants participate in a reaction
Products form as result of a reaction
• Free energy is the amount of energy available to perform work Exergonic Reactions - Products have less free
energy than reactants (release energy)
Endergonic Reactions - Products have more free energy than reactants (require energy input)
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ATP: Energy for Cells• Adenosine triphosphate (ATP)
High energy compound used to drive metabolic reactions
Constantly being generated from adenosine diphosphate (ADP)
• Composed of: Adenine, ribose (together = adenosine), and three
phosphate groups• Coupled reactions
Energy released by an exergonic reaction captured in ATP
ATP is used to drive an endergonic reaction
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The ATP Cycle
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P P P
adenosine triphosphateATP is unstable and hasa high potential energy.
ATP
The ATP Cycle
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P P P
P
adenosine triphosphateATP is unstable and hasa high potential energy.
ATP
Endergonic Reaction:
• The hydrolysis of ATP releases previously stored energy, allowing the change in free energy to do work and drive other processes.
• Has negative delta G.
• Examples: protein synthesis, nerve conduction, muscle contraction
ATP +
The ATP Cycle
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P P + P
P P P
+
P
adenosine triphosphateATP is unstable and hasa high potential energy.
ATP
Endergonic Reaction:• The hydrolysis of ATP releases Previously stored energy, allowing the change in free energy to do work and drive other processes.• Has negative delta G.• Examples: protein synthesis, nerve conduction, muscle contraction
adenosine diphosphate phosphateADP is more stable and has lower potential energy than ATP.
+ADP
The ATP Cycle
13
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P P + P
P P P
+
+ P
Exergonic Reaction:
• Creation of ATP from ADP and Prequires input of energy from Other sources.
• Has positive delta G.
• Example: cellular respiration
adenosine triphosphateATP is unstable and hasa high potential energy.
ATP
ADP
adenosine diphosphate phosphateADP is more stable and has lower potential energy than ATP.
Endergonic Reaction:
• The hydrolysis of ATP releases Previously stored energy, allowing the change in free energy to do work and drive other processes.
• Has negative delta G.
• Examples: protein synthesis, nerve conduction, muscle contraction