Chapter 9 Notes – How Cells Harvest Energy
Name:___________________
Cellular Respiration
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Cells harvest energy by ________________________________________ from one
molecule to another.
– aerobic respiration - ___________________________________
– anaerobic respiration - final electron acceptor is _________________________
__________________________
– fermentation - final electron acceptor is _________________________________
ATP
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Adenosine Triphosphate (ATP) is the energy currency of the cell.
– used to drive movement
– used to drive _________________________________
•
Most of the ATP produced in cells is ________________________________________.
– Enzyme is ________________________________ and provides a channel
through which ________________ can cross the membrane down their
________________________________.
 ____________________ is achieved by a rotary motor driven by a
_____________________.
NAD & NADH
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Nicotinamide adenine dinucleotide, NAD+, is a coenzyme found in all living cells.
The compound is a dinucleotide, since it consists of two nucleotides joined through their
phosphate groups: with one nucleotide containing an adenosine ring, and the other
containing nicotinamide.
In metabolism, NAD+ is involved in redox reactions, carrying ____________________
______________________________.
The coenzyme is therefore found in two forms in cells: NAD+ is an _________________ –
it accepts electrons from other molecules and becomes _________________________,
this reaction forms NADH, which can then be used as a ______________________ to
donate electrons. These electron transfer reactions are the main function of NAD+.
The Cellular isms
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Metabolism: is the set of ________________________________________________
______________________________.
– These processes allow organisms to _________________________________
_______________________________________.
– Usually divided into two categories.
• Catabolism and Anabolism
– Catabolism – ______________________
– Anabolism – ______________________
What are anabolic steroids used for? Who would want to use catabolic drugs?
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Catabolism: the set of metabolic pathways which ____________________________
___________________________-.
– Large molecules such as ________________________________ are broken
down into smaller units such as __________________________________
____________________________, respectively.
– These processes _______________________________
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Anabolism: the set of metabolic pathways that _______________________________.
– These reactions require ________________________.
– Anabolism is powered by _______________________. Many anabolic
processes are powered by _________________________________.
– Anabolic processes tend toward ______________________ organs and tissues.
– These processes produce ___________________________ of cells and
increase in ______________, a process that involves __________________ of
complex molecules.
Glucose Catabolism
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Cells __________________________ and produce ATP in two ways:
– _________________________________________
– aerobic respiration
 in most organisms, both are combined
 _________________
 _________________
 _________________
 _________________
Aerobic Respiration
Stage One – Glycolysis
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For each molecule of _________________e that passes through _____________, the
cell nets ______________ molecules.
Priming
– glucose priming
– cleavage and rearrangement
Substrate-level phosphorylation
– oxidation
– ATP generation
Priming Reactions
Priming Reactions
Glycolysis begins with the addition of _______________.
Two ___________________ phosphates from two
molecules of ________________ are added to the
______________ _________________ producing a sixcarbon molecule with two ______________________.
Cleavage Reactions
Cleavage Reactions
Then, the six-carbon molecule with two phosphates is
__________________________, forming two
__________________________________________.
Energy-Harvesting Reactions
Energy Harvesting Reactions
Finally, in a series of reactions, each of the two three-carbon
sugar phosphates is converted to ____________
_____________________. In the process, an energy-rich
_______________ is harvested as ___________________
and two ____________________ are formed.
Recycling NADH
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As long as ____________________
are available to be converted into
glucose, a cell can produce ATP.
– Continual production _______
__________ accumulation and
____________________.
 NADH must be recycled
into NAD+.
 aerobic respiration
 fermentation
Stage Two – Oxidation of Pyruvate
 Within __________________, pyruvate is ___________________, yielding acetyl-CoA,
NADH, and CO2.
Stage Three – Kreb’s Cycle
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Acetyl-CoA is oxidized in a series of nine reactions.
– two steps:
 priming
 energy extraction
Overview of Kreb’s Cycle
1: _________________
2-3: ________________
4: _________________
5: _________________
6:__________________
7: _________________
8-9: ________________
Kreb’s Cycle
Harvesting Energy by Extracting Electrons
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Glucose catabolism involves a series of __________________________that release
energy by ________________________________________ to oxygen atoms.
– Energy is harvested from glucose molecules in ____________________, using
NAD+ as an electron carrier
Electron Transport
Stage Four – Electron Transport Chain
 NADH molecules carry _________________ to the _______________________,
where they transfer ________________ to a series of membrane-associated proteins.
Electron Transport Chain
Chemiosmosis
ATP Generation
This process begins with
____________ the product of
________________, and
ends with the
_________________.
Theoretical Yield of Aerobic Respiration
Regulating Aerobic Respiration
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Control of glucose catabolism occurs at two key points in the catabolic pathway.
– glycolysis - ___________________________
– Krebs cycle - _________________________
Electron Transport System (Video)
Video
 In the mitochondrion, the energy stored in NADH is used to generate a proton gradient across
the mitochondrial membrane and the energy of the proton gradient is used to make ATP.
 When glucose is oxidized during glycolysis and the Krebs Cycle, the co-enzymes NAD and
FAD are reduced to NADH and FADH2.
 Inside the mitochondrial matrix, the electrons from NADH are transferred to the electron carrier
Coenzyme Q by NADH dehydrogenase, and the protons are transferred across the membrane
to the intermembrane space.
 Coenzyme Q carries the electrons to the cytochrome bci complex. As the electrons move from
the bci to cytochrome c, more protons are carried from the inside to the outside of the
membrane.
 Electrons are also transferred from FADH2 to Coenzyme Q, with the protons being transferred
across the membrane.
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Cytochrome c transfers electrons to the cytochrome c oxidase complex. Protons are also
transferred to the outside of the membrane by the cytochrome c oxidase complex.
The cytochrome oxidase complex then transfers electrons from cytochrome c to oxygen, the
terminal electron acceptor and water is formed as the product.
The transfer of protons to the intermembrane space generates a proton motive force across
the inner membrane of the mitochondrion.
Since membranes are impermeable to ions, the protons that reenter the matrix pass through
special proton channel proteins called ATP synthase.
The energy derived from the movement of these protons is used to synthesize ATP from ADP
and phosphate. Formation of ATP by this mechanism is referred to as oxidative
phosphorylation.
Control of Glucose Catabolism
Catabolism of Proteins and Fats
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Proteins are utilized by ___________________________ their amino acids, and then
metabolizing the product.
Fats are utilized by beta-oxidation.
Cellular Extraction of Chemical Energy
Fermentation
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Electrons that result from the glycolytic breakdown of glucose are donated to an
organic molecule.
– regenerates NAD+ from NADH
 ethanol fermentation
 lactic acid fermentation