Section A: The Principles of Energy Harvest

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Section A The Principles of Energy Harvest

• Cellular respiration and fermentation ?????? are
  catabolic, energy-yielding ?????? ?????? ????
  pathways
• Cells recycle the ATP they use for work
• Redox reactions ??????? ???????-???????? release
  energy when electrons move closer to
  electronegative atoms
• Electrons fall ????? from organic molecules to
  oxygen during cellular respiration
• 5. The fall of electrons during respiration is
  stepwise ????????, via NAD and an Electron
  Transport Chain

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Respiration
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??????? ????????????
??????? ??????
1- ??????? ???????
??????
3- ??????? ??????
????? ????????
2- ??????? ????????
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Fig. 9.1, Page 156
A)- Light energy
B)- Photosynthesis
1)- CO2 H2O
C)- Cellular respiration
ATP
Energy (heat)
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1. Cellular respiration and fermentation are
catabolic, energy-yielding ????? ?????? pathways

• Organic molecules store energy in their
  arrangement of atoms.
• Enzymes catalyze the systematic degradation of
  organic molecules that are rich in energy to
  simpler waste products with less energy.
• Some of the released energy is used to do work
  and the rest is dissipated as heat.
• Metabolic pathways that release the energy stored
  in complex organic molecules are catabolic ????.
• Fermentation is a type of catabolic process leads
  to the partial degradation ?????? ?????? of
  sugars in the absence of oxygen.
• Cellular respiration is a more important
  catabolic process, uses oxygen as a reactant to
  complete the breakdown of a variety of organic
  molecules.
• This process is
• Organic compounds O2 -gt CO2 H2O Energy
• Carbohydrates, fats, and proteins can all be used
  as the fuel, but we will start learning with
  glucose.
• C6H12O6 6O2 -gt 6CO2 6H2O Energy (ATP heat)

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Cellular Respiration
Energy
Food (Fuel of energy)
Respiration
Cellular Activities
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2. Cells recycle the ATP they use for work

• ATP (Adenosine Tri-Phosphate) is the important
  molecule in cellular energetics ?????? ?????
  ??????.
• The attachment of three negatively-charged
  phosphate groups (P) is an unstable ??? ?????,
  energy-storing ???? ?????? arrangement.
• Loss of the end phosphate group release energ
• The price of most cellular work is the conversion
  of ATP to ADP and phosphate (P).
• An animal cell regenerates ???? ????? ATP from
  ADP by adding P via the catabolism ??? of organic
  molecules.

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Adenosine Tri-Phosphate (ATP)
Adenosine
H2O
Triphosphate
Energy
P
Adenosine Di-Phosphate
Fig. 6.8, Page 94
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The transfer of the terminal phosphate group from
ATP to another molecule is phosphorylation
???????????. This changes the shape

of the receiving molecule
in order to work

(transport, mechanical,

or chemical). When the phosphate groups leaves
the molecule, the molecule returns to its
original shape (stop).
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How dose ATP drive cellular work ?
P
Microtubule
Organelle
P
Energy
Fig. 9.2, Page 157
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3. Redox reactions release energy when electrons
move closer to electronegative atoms

• Catabolic pathways relocate ???? ????? the
  electrons stored in food molecules, releasing
  energy that is used to synthesize ?????? ATP.
• Oxidation-reduction reactions (Redox reactions)
• Are reactions that result in the transfer of
  one or more electrons from one reactant to
  another
• Oxidation
• Is the loss ???? of electrons.
• Reduction
• Is the addition ?????? of electrons.

Redox reactions require both a donor and
acceptor of e.

e-
Energy
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4. Electrons fall from organic molecules to
oxygen during cellular respiration

• In cellular respiration, glucose and other fuel
  molecules are oxidized, releasing energy.
• Glucose is oxidized, oxygen is reduced, and
  electrons loose potential energy.
• H is the source of electrons that transfere to O.
• Thus, molecules that have an abundance of ???? ??
  hydrogen are excellent fuels because their bonds
  are a source of electrons that fall closer to
  oxygen.
• Enzymes lower the barrier of activation energy,
  allowing these fuels to be oxidized slowly.
• When H moves to O, it leaves bonds which
  degenerated to release energy.
• The resulting energy is used by the cell to
  synthesis ATP .

Energy 686 kcal/mol
Energy
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5. The fall of electrons ???????? ???????????
during respiration is stepwise ?????, by NAD
and an electron transport chain

• Cellular respiration does not oxidize glucose in
  a single step that transfers all the hydrogen in
  glucose to oxygen at one time.
• Rather, glucose and other fuels are broken down
  gradually ??????? in a series of steps, each
  catalyzed by a specific enzyme.
• At key steps ?? ??????? ????????, hydrogen atoms
  move from glucose and passed first to the
  coenzyme NAD (Nicotinamide Adenine
  Dinucleotide).
• Dehydrogenase enzymes strip two hydrogen atoms
  from the fuel (e.g., glucose), pass two electrons
  to NAD and release H.

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• This changes the oxidized form, NAD, to the
  reduced form NADH.
• NAD functions as the oxidizing agent in many
  of the redox steps during the catabolism of
  glucose.

As electrons fall from NADH to oxygen, Their
energy is tapped to synthesize ATP.
Fig. 9.4
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• Cellular respiration uses an electron transport
  chain ????? ??? ???????????? to break ????????
  the fall of electrons to O2 into several steps
  ??? ?????.

• The electron transport chain, consisting of
  several molecules (primarily proteins), is built
  into the inner membrane of a mitochondrion.
• NADH takes electrons from food to the top of
  the chain.
• At the bottom, oxygen captures the electrons
  and H to form water.
• The free energy change from top to bottom is
  -53 kcal/mole of NADH.
• Electrons are passed by increasingly
  electronegative molecules in the chain until they
  are caught by oxygen (the most electronegative).

Fig. 9.5, Page 159
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Summary of electron Fall steps during
respiration
- Falling of all H atoms from glucose to O is
gradually not at once.
- It occurs in steps, each one is catalyzed by an
enzyme.
- H atoms of glucose pass first to the co-enzyme
NAD to form NADH
- Then from NADH to electron transport chain, and
finally to O and releases energy to form ATP.
Energy
Page 158 Fig. 9.5