1. _____________________ and ________________ are catabolic, energy-yielding pathways

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1. _____________________ and ________________ are
catabolic, energy-yielding pathways
CHAPTER 9CELLULAR RESPIRATION
Catabolic processes
Enzyme
Complex molecule (High energy)
Simpler molecule (Low energy)
heat energy
2 common types
1. ________________- to be discussed later

• Organic compounds CO2 H2O Energy

2. ____________________-

• Organic compounds O2 CO2 H2O Energy

• This process uses _________.

Note

• This occurs in the _______________

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• An example of cellular respiration- _____________
  of glucose
• C6H12O6 6O2 6CO2 6H2O Energy
  (ATP heat)

Glucose

• An ________________reaction
• D G - 686 kcal per mole of glucose.
• Drives the generation of ATP from ADP

ATP then ____________________ other molecules,
allowing them to do work
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2. _______ reactions release ___________ when
electrons move closer to _____________ atoms

• _______ (reduction-oxidation) reactions- transfer
  of electrons from one reactant to another or
  changes bond type (single to double).
• The loss of electrons is called _____________.
• The addition of electrons is called _____________.

• Example
• NaCl Na Cl-
• sodium is ____________and chlorine is
  ____________
• Na is the ____________________ and reduces Cl.
• Cl is the _____________________ and oxidizes Na.

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3. Electrons fall from organic molecules to
________ during cellular respiration

• In the summary equation of cellular respiration
  C6H12O6 6O2 6CO2 6H2O
• Glucose is ___________, oxygen is ____________,
  and electrons loose potential energy.

• At key steps, hydrogen atoms are stripped from
  glucose and passed first to a coenzyme, like NAD
  (nicotinamide adenine dinucleotide).

• Dehydrogenase enzymes strip two hydrogen atoms
  from the fuel (e.g., glucose), pass
  _______________ ________to NAD (to make NADH)
  and release H.
• H-C-OH NAD -gt CO NADH H

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• NAD functions as the __________________ in many
  of the redox steps during the catabolism of
  glucose.

• Energy is tapped to synthesize ATP as electrons
  fall from __________ to oxygen.

Fig. 9.4
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• The________ ___________
• _______ breaks the fall of electrons to __ into
  several steps.

Fig. 9.5

• ________ shuttles electrons to the top of the
  chain.
• At the bottom, oxygen captures the ___________
  and ___ to form water.
• The free energy change from top to bottom is
  ___ kcal/mole of NADH.

Energy used to make ATP!
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1. Respiration involves glycolysis, the Krebs
cycle, and electron transport
2. ______________ (in mitochondrial matrix)
3. ___________ ____________ (In inner
mitochondrial membrane)
1. __________ (In cytoplasm)
Fig. 9.6
End result ATP is generated
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Add up total ATP generated 22628___
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• In the electron transport chain-
• the _________ move from molecule to molecule
  until they combine with oxygen and hydrogen ions
  to form __________.
• As they are passed along the chain, the energy
  carried by these electrons is stored in the
  mitochondrion in a form that can be used to
  synthesize ATP via _______________________________
  ______.
• Oxidative phosphorylation produces almost ____ of
  the ATP generated by respiration.

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These are generated by ___________________________
___
What is substrate level phosphorylation?
Enzyme

• An _______ transfers a phosphate group from an
  organic molecule (the substrate) to ____, forming
  ____.

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2. Glycolysis

• Glucose, a six-carbon sugar, is split into two,
  3-carbon sugars then into ________.
• Each of ___ steps in glycolysis is catalyzed by a
  specific _________.

• Divided into two phases
• an _______________ __________
• 2 ATP used
• an _____________ _________.
• 4 ATP 2 NADH produced

Net 2 ATP 2 NADH
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Glycolysis
Energy investment phase
1st Phosphate group added
2nd Phosphate group added
Two 3-carbon molecules, each with one phosphate
Fig. 9.9a
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Energy payoff phase
2 PO4
1 PO4
0 PO4
Fig. 9.9b
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3. The Krebs cycle completes the energy-yielding
__________ of organic molecules
Krebs
Glycolysis

• If ___________ is present, pyruvate enters the
  _________________ where enzymes of the Krebs
  cycle complete the ______________ of the organic
  fuel to carbon dioxide.

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• What happens to pyruvate?
• Answer- Pyruvate is modified to ____________
  which enters the Krebs cycle in the matrix.
• 1. A _______________ group is removed as CO2.
• 2. A pair of ______________ is transferred from
  the remaining two-carbon fragment to NAD to form
  NADH.
• 3. The oxidized fragment, acetate, combines
  with coenzyme A to form ___________

Fig. 9.10
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• The Krebs cycle consists of ____ steps.

Named after Hans Kreb 1930s

• Each cycle produces
• one ATP by _____________ _____________
• three ________
• and one ______

Fig. 9.12
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• The conversion of pyruvate and the Krebs cycle
  produces large quantities of _______________.

2 carbon atoms enter
2 carbon atoms released as CO2
Note the Krebs cycle is never depleted of
________ 2 in, 2 out
Fig. 9.11
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4. The inner mitochondrial membrane couples
_____________ to ATP synthesis

• Only __ of __ ATP produced by respiration of
  glucose are derived from ________________
  ________________________.
• The vast majority of the ATP comes from the
  energy in the ________ carried by ______ (and
  ________).

• Thousands of copies of the electron transport
  chain are found in the _________ (the inner
  membrane of the mitochondrion).
• Electrons drop in _____________ as they pass down
  the electron transport chain.

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• Electrons carried by __________ are transferred
  to the first molecule in the electron transport
  chain, _____________________.
• The electrons continue along the chain which
  includes several ____________ proteins and one
  lipid carrier.
• The electrons carried by _____ have lower free
  energy and are added to a later point in the
  chain.

Electrons

• Electrons from NADH or FADH2 ultimately pass to
  oxygen.
• The electron transport chain generates no ATP
  directly.

Note
Fig. 9.13
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Then where does the ATP come from??

• A protein complex, ___ _______, in the cristae
  actually makes ATP from ADP and Pi.
• ATP uses the energy of a _____________ (from the
  electron transport chain) to power ATP synthesis.
• This __________________ develops between the
  intermembrane space and the ________.
• Termed _______________ ______________________

Fig. 9.14
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• This coupling of the redox reactions of the
  electron transport chain to ______________ is
  called _____________________.

Fig. 9.15

• In plants- light supplies the ____________
• In bacteria, the H gradient is across the plasma
  membrane

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5. Cellular respiration generates many ___
molecules for each _____ molecule it _________ a
review

• Most energy is from __________________________

glucose NADH ET chain proton-motive
force ATP

• A one six-carbon glucose molecule is oxidized to
  six CO2 molecules.
• Some ATP is produced by substrate-level
  phosphorylation

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Maximum yield is 38 ATP
Fig. 9.16
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• How efficient is respiration in generating ATP?
• Complete oxidation of glucose _______
  kcal/mole.
• Formation of each ATP requires _____ kcal/mole.
• Efficiency of respiration is
• ____ kcal/mole x ___ ATP/glucose ___.
• 686 kcal/mole glucose
• The other approximately 60 is lost as ______.
• Cellular respiration is remarkably efficient in
  energy conversion.

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6. _____________ enables some cells to produce
ATP without the use of _______

• Oxidation refers to the loss of _______to any
  electron acceptor, not just to oxygen.
• In glycolysis, NAD is the ________ agent, not
  O2.
• Glycolysis generates _____ whether oxygen is
  present (aerobic) or not (anaerobic).

Fig. 9.17a
Problem- Fermentation (anaerobic catabolism)
still requires NAD to accept electrons.
Solution-In _______________, NAD comes from the
conversion of pyruvate to _________
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• A second solution to the NAD problem
• __________________________
• ( pyruvate is reduced directly by NADH to form
  ___________)
• Muscle cells switch from _________respiration to
  lactic acid ___________ to generate ATP when __
  is scarce.
• The waste product, lactate causes muscle
  fatigue but ultimately it is converted back to
  pyruvate in the liver.

Fig. 9.17b
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Compare respiration and fermentation
Similarities

• Both use glycolysis to generate _______
• Both use NAD as an _________________.

Respiration
Fermentation
Aerobic
Anaerobic
Type
NAD regeneration
Organic molecules
___
Energy yield
__ ATP
___ ATP
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• At a cellular level, human _________ cells can
  behave as facultative anaerobes, but ________
  cells cannot.
• For facultative _________, pyruvate is a fork in
  the metabolic road that leads to two
  alternative routes.

Fig. 9.18
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7. How do other ________________ fit into
glycolysis and the Kreb cycle??

• Answer- ____________ _____________ can all enter
  the pathway

• ________ are degraded to amino acids, then
  deaminated (nitrogen secreted as urea, ammonia)

• ______________are broken down to glucose.

• ______must be digested to glycerol and fatty
  acids.

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• Intermediaries in glycolysis and the Krebs cycle
  can be diverted to _____________ pathways.
• Examples
• a human cell can synthesize about ______ the 20
  different amino acids by modifying compounds from
  the _____________.
• ___________ can be synthesized from pyruvate and
  fatty acids from acetyl CoA.

• Excess carbohydrates and proteins can be
  converted to _______ through intermediaries of
  glycolysis and the Krebs cycle.

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8. _____________________ control cellular
respiration

• Basic principles of ____________________ regulate
  the metabolic economy.
• If a cell has an excess of a certain amino acid,
  it typically uses feedback inhibition to prevent
  the diversion of more intermediary molecules from
  the Krebs cycle to the synthesis pathway of that
  amino acid.
• The rate of catabolism is also regulated,
  typically by the level of _________ in the cell.
• If ATP levels drop, catabolism speeds up to
  produce more ATP.

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• Control of catabolism is based mainly on
  regulating the activity of __________ at
  strategic points in the catabolic pathway.
• One strategic point occurs in the third step of
  glycolysis, catalyzed by ______________________

• When ATP levels are high, inhibition of this
  enzyme slows ________________.

• _____________, the first product of the Krebs
  cycle, is also an inhibitor of phosphofructokinase
  .

Fig. 9.20