1. Chapter 6 Metabolism: Energy and Enzymes
Read chapter 6 of textbook
Read Enzyme Activity Lab in AP Lab Manual (#13)
Read pages 22 (chemical reactions and metabolic processes)
in CliffsAP (3rd)
Do MC questions on pg of Cliffs – Due Sept 17
Be sure you could answer the free response questions pg 29
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2. Chapter 6 Metabolism: Energy and Enzymes
Topics
6.1 Cells and the Flow of Energy
6.2 Metabolic Reactions and Energy Transformations
6.3 Metabolic Pathways and Enzymes
6.4 Metabolic Pathways and Oxidation Reduction
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3. Metabolism: Energy and Enzymes 6.1 Energy
Energy = capacity to do work or bring about a change
All living things need energy
Many kinds of energy
Kinetic energy
Energy of motion
Mechanical
Potential energy
Stored energy
Chemical energy
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4. Biology, 9th ed,Sylvia Mader
Chapter 06
Flow of Energy
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
sun
CO2
H2O
solar energy
producer
carbohydrate
heat
solar
energy
heat
heat
heat
heat
Chemical
energy
Mechanical energy
Metabolism

5. Metabolism: Energy and Enzymes 6.1 Energy
Two laws of thermodynamics
Law of conservation of energy
Energy cannot be created or destroyed, only converted from one form to another
Second law (Entropy)
Energy cannot be converted from one form to another without a loss of usable energy
Energy = Mass x The Velocity of Light squared
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6. Metabolism: Energy and Enzymes 6.1 Energy
Entropy
A measure of randomness or disorder
Things tend toward more entropy – takes energy to keep organized
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7. Biology, 9th ed,Sylvia Mader
Cells and Entropy
Chapter 06
H2O
C6H12O6
CO2
Glucose
Carbon dioxide
and water
• more organized
kinetic
energy
• less organized
• more potential energy
• less potential energy
• less stable (entropy)
• more stable (entropy) a. H+ H+
channel protein H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+
Unequal distribution
of hydrogen ions
Equal distribution
of hydrogen ions
• more organized
• less organized
• more potential energy
• less potential energy
• less stable (entropy)
• more stable (entropy) b.
Metabolism

8. Metabolism: Energy and Enzymes 6.1 Energy
Whole ecosystem also follows these rules
Ultimately all energy ends up as heat, which is very random energy (high entropy)
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9. Metabolism: Energy and Enzymes 6
Metabolism: Energy and Enzymes 6.2 Metabolic Reactions and Energy Transformations
Metabolism = sum of all reactions that go on in body
Free energy
= amount of energy (G) that is still available (free) to do work after a chemical reaction has occurred. (change in energy is designated delta G)
If delta G is negative it means the products have less energy than the reactants did. And the reaction will occur spontaneously
Exergonic – give off energy
Delta G is negative
ATP  ADP +P + free Energy
Endergonic – need energy
Delta G is positive – products have more free energy than reactants.
Free Energy + Reactants  Products
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10. Metabolism: Energy and Enzymes 6
Metabolism: Energy and Enzymes 6.2 Metabolic Reactions and Energy Transformations
Coupled reactions
Many reactions in body are coupled
One gives off energy and the other uses it
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11. Metabolism: Energy and Enzymes 6
Metabolism: Energy and Enzymes 6.2 Metabolic Reactions and Energy Transformations
ATP; energy for Cells
Adenosine triphosphate is a common source of stored energy for cells
Provides energy for:
Chemical work – synthesizing macromolecules
Transport work – pumps substances across membranes
Mechanical work – muscle contractions, cilia, flagella, cytoskeleton
Energy stored in third phosphate bond
ATP is a nucleotide
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12. Coupled Reactions 12 Metabolism Biology, 9th ed,Sylvia Mader
Chapter 06
Slide #12
Metabolism
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1
Myosin assumes its
resting shape when
It combines with ATP. 2
ATP splits into ADP and p , causing myosin to change its shape and allowing it to attach to actin. 3
Release of ADP and p cause myosin to again change shape
and pull against actin,
generating force and
motion.
actin P
myosin
ATP
ADP 12

13. Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes
Series of consecutive reactions
Each step catalyzed by an enzyme
Enzymes (organic catalysts) are made of proteins
Lower the activation energy
Substance enzyme reacts with is called a substrate
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15. Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes
Importance of Enzymes
Enzymes are needed for most chemical reactions to occur in living cells, lower activation energy
Such as getting “energy” from sugars
We would die without enzymes
Enzyme acts on a substrate
Enzyme names often end in “ase”
Enzymes are organic (usually globular proteins) catalysts
Speed up a reaction without being used up themselves
Can speed up a reaction by as much as a million times
Starch degradation by enzyme amylase animation ..\..\Biology\Biology Clipart Movies Animations Sounds\Biology movies\starch degrade animation.dir
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16. Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes
How Enzymes Work
Enzymes have active sites
Enzyme-substrate complex
Bind to specific spot on substrate
Can put substrates together or break them apart
Two theories to explain how
Lock and key
Induced fit
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17. Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes
Fit together like a lock and key
Hydrogen proxide
catalase
Water and oxygen
Synthesis
catalase
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Degradation

18. Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes
Induced fit
Once enzyme substrate complex has formed, enzyme changes shape slightly for a better fit
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19. Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes
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21. Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes
Factors affecting ezymatic speed
Many factors can affect enzyme action
Substrate concentration
Temperature pH
Enzyme concentration
Enzyme inhibition
Enzyme co-factors
Affect only the rate of the reaction, not the amount of end products
Only very small amounts of enzyme are needed to catalyze reactions
The enzyme catalase (present in our liver) can break up 5 Million molecules of hydrogen peroxide in one minute (at Oo C = 32o F).
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22. Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes
Read Lab 2 – Enzyme Catalysis
Oct 14th lab
in your AP Lab Manual pg
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23. Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes
What is optimal temp for this enzyme in Fahrenheit degrees?
Temperature
Generally higher temp increases rate of reaction
In living tissues, don’t want high temp
Enzymes work best at optimal temp
Usually the normal temp of the cell they are in
If temp too high enzymes are denatured
Boiled egg
Formula: oF = (9/5) oC + 32
oF = (9/5) o = 107.6oF
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24. Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes
Enzyme and substrate concentrations
Increasing the amount of substrate or enzyme will increase the reaction rate, but only up to a maximum point
Maximum point – adding more enzyme will not increase rate any more.
Start
Fixed amount of substrate-add more and more enzyme.
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25. Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes
Maximum point – adding more substrate will not increase rate any more.
Start
Fixed amount of enzyme- add more and more substrate.
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26. Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and EnzymespH
Enzymes also have an optimal pH at which they work best
Optimal pH for pepsin?
Where might you find it?
Optimal pH of trypsin?
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27. Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes
Enzyme inhibition
Competitive inhibition
Molecule binds and blocks active site
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28. Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes
Enzyme inhibition
Non-competitive inhibition
Molecule does not bind to active site, binds to allosteric site
Feedback inhibition (see next slide) works this way
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29. Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes
Feedback Inhibition
Many biological systems (metabolic pathways)work this way
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31. Metabolism: Energy and Enzymes 6.3 Metabolic Pathways and Enzymes
Enzyme cofactors
Some enzymes are not made entirely of protein, contain other substances that help them function
These are substances are called cofactors
Can be inorganic (such as minerals Cu, Zn, Fe) or ,
Can be organic- called coenzymes organic –non protein (such as vitamins)
Some vitamins are coenzymes
Humans cannot synthesize most vitamins, so need to take in diet
Help enzyme perform it’s function
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32. Metabolism: Energy and Enzymes 6.4 Organelles and the Flow of Energy
Oxidation and Reduction
Occur together = redox
Oxidation = loss of electrons
In living systems H often accompanies the electron (usually as e- + H+)
So usually means loss of hydrogen atom
Reduction = gain of electrons
So usually means gain of hydrogen atom
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33. Metabolism: Energy and Enzymes 6.4 Organelles and the Flow of Energy
Two energy capturing pathways that use redox reactions (we will look at in the next two chapters)
Photosynthesis – Ch 7
Cell respiration – Ch 8
Both systems make use of an electron transport system and produce ATP
We will look closer at these systems in chapters 7 and 8.
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34. Metabolism: Energy and Enzymes 6.4 Organelles and the Flow of Energy
Photosynthesis overview
Takes energy from the sun and converts it into chemical energy
Equation Summarizing Photosynthesis
6CO H2O  C6H12O6 + 6H2O + 6O2
Light
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35. Metabolism: Energy and Enzymes 6
Metabolism: Energy and Enzymes 6.4 Metabolic Pathways and Oxidation Reduction
Photosynthesis overview
Many reactions involved
At one point, a coenzyme called NADP+, is used to carry electrons from one place to another – usually to the ETS
NADP+ + 2e- + H+  NADPH
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36. Metabolism: Energy and Enzymes 6.4 Organelles and the Flow of Energy
Cell Respiration Overview
Takes energy from glucose and makes ATP
Equation summarizing cell respiration
C6H12O6 + 6H2O + 6O2  6CO2 + 12H2O + 36 ATP + heat
Uses coenzyme NAD to carry electrons to ETS
NAD+ (is reduced) + 2e- + 2H+  NADH + H+
Oxidation
Reduction
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37. Metabolism: Energy and Enzymes 6.4 Organelles and the Flow of Energy
Electron Transport System Overview
Series of carrier molecules that pass electrons along
Electrons lose a little bit of energy each time passed
Carriers are oxidized and reduced
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39. Metabolism: Energy and Enzymes 6.4 Organelles and the Flow of Energy
Will discuss in more detail later
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40. Metabolism: Energy and Enzymes 6. 4 6
Metabolism: Energy and Enzymes Organelles and the Flow of Energy
ATP Production Overview
Uses energy from ETS
ETS located within membranes of mitochondria and chloroplasts
Process called chemiosmosis
ETS deposits H on one side of the membrane
H flow down electrochemical gradient through ATP synthase complex
Flowing through the complex provides the energy to add a P to ADP  ATP
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Animations from

41. Metabolism: Energy and Enzymes 6.4 Organelles and the Flow of Energy
Chemiosmosis blah, blah blah, blah blah, blah blah, blah blah, blah…..
Peter Mitchell
1978 Nobel Prize
Chemiosmosis Theory
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42. ATP synthesis and the electron transport chain animation
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43. Metabolism: Energy and Enzymes 6.4 Organelles and the Flow of Energy
Chemiosmosis website animation
From:
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44. Read Connecting the Concepts with the Big Ideas pg 115
The End
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