Bioenergetics Learning Goals
1. Understand laws of thermodynamics and how
they relate to biological systems
2. Understand that organisms are interdependent,
open systems that respond to their environment by
managing their energy resources
3. Understand how mitochondria and chloroplasts work
with the cell to harvest chemical energy, or convert
solar energy to chemical energy
4. Understand the fundamental cellular process of
chemiosmosis and its central role in ATP production
Metabolism/Cellular Energetics
(The central concept of Semester 1)
• The Good News:
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You know most of this stuff already
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Enzymes
Semipermiable Membranes
Active Transport
Potential/Kinetic/
Chemical Energy
Macromoleules/Monomers
ATP
Kinases
Metabolism
• The New Ideas:
• Catabolism and Anabolism
• The Stages of Cellular
Respiration
• Chemiosmosis
• Oxidative Phosphorylation
• Light Dependent/Light
Independent Reactions
• Photophosphorylation
Key Concepts
• Metabolism
• Energy:
Free Energy:
• Spontaneous vs. non spontaneous
reactions
• ATP couples Reactions
• Dynamic Equilibrium
College Board “Performance Objectives”
• Describe the role of ATP in coupling a cell’s catabolic
and anabolic reactions.
• Explain how chemiosmosis functions in bioenergetics
• How are organic molecules broken down by the
catabolic pathways of cellular respiration
• Explain the role of oxygen in energy-yielding
pathways of cellular respiration
• Explain how cells generate ATP in the absence of
oxygen.
Definitions
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Metabolism:
Metabolic Pathway:
Catabolism:
Anabolism:
Energy
• Energy:
• Kinetic Energy:
• Potential Energy:
• Chemical Energy
The laws of energy transformation
• 1st Law of
Thermodynamics:
(pg. 143)
• 2nd Law of
Thermodynamics:
FIGHT
ENTROPY!
More definitions
• Free Energy:
• Exergonic =
• Endergonic =
Changes in Free Energy
How does this apply to Biological
Systems?
C:
A or BS:
How are Catabolism and
Anabolism “coupled”?
The hydrolysis of ATP yields 7.3kCal/mole of ATP
How does this apply to Biological
Systems?
What is ATP?
How does ATP Perform
Work?
ATP Phosphorylates other molecules!
Examples of ATP at work:
Bioenergetics: The Big Picture
• Producers
• Consumers
Producers: convert solar
energy into chemical energy
Producers: convert solar
energy into chemical energy
How does Bioenergetics relate
to other concepts in Biology?
Bioenergetics: The Big Picture
• The Equations:
• In general…
– Organic Molecules
– Food
• Combustion or Oxidation of Glucose (∆G) =
• Number of ATP/Glucose Molecule
• Regeneration of ATP (from ADP & Pi) (∆G) =
Consumers (start with organic molecules, give off CO2)
• Some Details:
Glycolysis
– Fermentation
Cellular Respiration
These are re-dox reactions
Cellular Respiration
• Oxidation of Food Molecules by Oxygen
– Releases Energy
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Cumulative Function of 3 metabolic stages
Glycolysis
Citric Acid (Kreb’s) Cycle
Oxidative Phosphorylation
Cellular Respiration
Where…How…Connections
Our Objective
• Learn the important details about the 3
metabolic stages of cellular respiration
• Glycolysis, Citric Acid Cycle, Oxidative
Phosphorylation
• Remember that the cell is using glucose
to make ATP (it’s harvesting energy)
• Remember these stages are connected!
SLP: Substrate Level
Phosphorylation
Glycolysis
• Literally…
• (2 phases)
Fig 9.8
Glycolysis 1: Energy Investment
• What happens,
why?
• What’s the “end”
product?
Glycolysis 2: Energy Return
• G3P is…
• SLP…
• The “end” product(s):
– ATP
– NADH
– Pyruvate
Connections: Pyruvate is Oxidized
1)
2)
3)
Citric Acid Cycle:
• It is a cycle!
• Where does it
happen?
• What are the
outcomes?
Oxaloacetate
(4-C)
Citrate
(6-C)
Citric Acid Cycle:
The Bottom Line…
Pyruvate is completely
oxidized and the energy is
converted to NADH and
FADH2 (ETC) and ATP via
S.L.P.
8 NADH and 2 FADH2
per glucose molecule
The intersection
between Glycolysis
and OXY PHOS
Oxidatative Phosphorylation
Overview:
During oxidative
phosphorylation,
chemiosmosis couples
electron transport to ATP
Synthesis.
Oxidative Phosphorylation 1:
E.T.C.
• Where?
P.C.
• What?
• How?
• What else happens?
Oxidative Phosphorylation 2
• So What?
– E.T.C. drives…
– ATP Synthase
Oxidative Phosphorylation 3: Putting it all together
1)
2)
3)
Chemiosmosis!
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2)
An energy-coupling
mechanism that
uses energy stored
in the form of a H+
gradient across a
membrane to drive
cellular work.
3)
1)
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Hints for building ETC Model
1.
2.
3.
4.
Start with aligning yourselves from least electronegative
(greatest Potential energy) to most electronegative. This
should be a physical change in height. Use stools, chairs,
bench tops etc.
Get comfortable passing electrons down from least
electronegative molecule to most electronegative molecule. (I
suggest saying “Grrrr” when you get reduced. Perhaps the
“Grrr” gets louder as electo-negativity increases.)
Once you are comfortable passing electrons, add in the
protons moving across the protein complexes, into the
intermembrane space and then through ATP synthase to
generate ATP.
Use your textbook, each other, and me as a resource. I will be
videotaping the process and product.
Cellular Respiration: Review (F9.16)
(don’t look at the book, let’s work this out together.)
Reactants, Products, major intermediates, processes, specific locations
Net ATP Production
Mode of ATP Production
ATP Accounting?
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Catabolism of Glucose, ∆G = -686 kCal/mol
Anabolism of ATP from ADP + Pi, ∆G = 7.3 kCal/mol
About 36-38 mol ATP/mol glucose
ATP synthesis is roughly…
…efficient
Where does the rest of the energy go?
ATP/NADH
ATP/FADH2
ATP/H+
Beyond Cellular Respiration
Fermentation: an alternate pathway for
energy production (ATP synthesis)
• Fermentation is…
• fermentation starts with...
• F.A…
• O.A…
Fermentation: (2 processes)
• What do these pathways
have in common?
• What’s different?
• What’s the significance of
alcohol fermentation?
• What’s the significance of
lactic acid fermentation?
• What else do these
pathways have in
common?
Comparing Fermentation and Cellular
Respiration
• Commonalities:
• Differences:
Oxidative Phosphorylation
Glycolysis is ancient…
• How old is it?
– Est. to be ________
• What else do we know
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Regulation of Cellular Respiration
Enzymatic Regulation:
Allosteric Regulation
Fluctuating concentrations
ATP vs. ADP + Pi
Life on Earth is solar powered
Bioenergetics: Background Info
• Producers
• Consumers
Photosynthesis: Biochemistry conserved
throughout several Domains
Across four levels of organization
• Plants
• Leaves
• Mesophyll Cells
• Chloroplasts
A Closer Look at the Organelles
PS: 2 Reactions in 1 organelle
Food for thought:
How are cellular respiration and photosynthesis
similar? How are they different? Think about it on
an organismal level, on an organelle level, and
on a biochemical level.
More Food…Check out Figure 10.16
Light Reactions begin with…
• Light (Visible Light)
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is Absorbed by 3 Pigments
Why peaks?
• Chlorophyll a
• Chlorophyll b
• Carotenoids
So What?
• So what happens when
light is absorbed?
photosystem
If photosystems are membrane-bound, then you
can build a “battery”
If we could get down on the thylakoid membrane…
No, really, so what?
• Where does the
electron from water
go once it replaces
the electron in the
chlorophyll molecule
in the center of PSII
(PS 680)?
Just a few questions, if you please
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Is there any oxidation happening?
Is there any reduction happening?
Is there any catabolism happening
Is there any anabolism happening?
Is there any coupling occuring?
What is this process called?
What happens?
Well, chemiosmosis happens.
What do the Light Reactions produce?
• Light Reactions…
Light Reaction Review…
Gimmie Some Sugar!
Photosynthesis: The Big Picture
Location
Energy conversions
Material inputs/outputs