Topic 3.7

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Topic 3.7 Cell Respiration How Cells Harvest
Chemical Energy

Cellular respiration is the set of the metabolic
reactions and processes that take place in the
cells of organisms to convert biochemical energy
from nutrients into adenosine triphosphate (ATP),
and then release waste products
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Breathing and Cell Respiration are related
HOW?
BREATHING
O2
CO2
Lungs
Muscle cells carrying out
CO2
O2
Bloodstream
CELLULAR RESPIRATION
Sugar O2 ? ATP CO2 H2O
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Cellular Respiration uses oxygen and glucose to
produce Carbon dioxide, water, and ATP.
Glucose
Oxygen gas
Carbon dioxide
Water
Energy
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Reduction and Oxidation O.I.L.R.I.G. Oxidation
is losing electrons (or hydrogens) from an
element or molecule Reduction is gaining of
electrons (or hydrogens) by an element or molecule
Loss of hydrogen atoms
Energy
Glucose
Gain of hydrogen atoms
Glucose gives off energy and is oxidized
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Reduction and Oxidation OILRIG Gain
or loss of electrons is often in the form of
hydrogen. The hydrogen is then passed to a
coenzyme such as NAD
Oxidized
Reduced
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Reduction and Oxidation These co-enzymes are
very important for cell respiration because they
transfer high-energy electrons to electron
transport systems (ETS).
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Reduction and Oxidation As the electrons move
from carrier to carrier, energy is released in
small quantities.
Electron transport system (ETS)
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General Outline - Initial Reactions for bot
Aerobic and Anaerobic cellular respiration are
the same GLYCOLYSIS
Glucose
Glycolysis
No Oxygen Anaerobic
Oxygen Aerobic
Pyruvic Acid
Fermentation
Transition Reaction
Krebs Cycle
ETS
36 ATP
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Generation of ATP What is phosphorylation? The
transfer of a phosphate, phosphate groups to a
molecule One type Substrate Level
Phosphorylation
Enzyme

Adenosine
substrate
Adenosine
product
Figure 6.7B
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Glycolysis Where? The cytosol What? Breaks
down glucose to pyruvic acid How? see
following slides
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Glucose
Steps A fuelmolecule is
energized,using ATP.
1
3
Step
Glycolysis
1
Glucose-6-phosphate
2
Fructose-6-phosphate
Energy In 2 ATP
3
Fructose-1,6-diphosphate
Step A six-carbonintermediate splits into
two three-carbon intermediates.
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4
Glyceraldehyde-3-phosphate (G3P) (TRIOSE
PHOSPHATE)
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Step A redoxreaction generatesNADH.
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1,3-Diphosphoglycerate(2 molecules)
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Steps ATPand pyruvic acidare produced.
3-Phosphoglycerate(2 molecules)
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Energy Out 4 ATP
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2-Phosphoglycerate(2 molecules)
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2-Phosphoglycerate(2 molecules)
NET 2 ATP and 2 NADH
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Pyruvic acid
(2 moleculesper glucose molecule)
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What is NAD and NADH H ? Nicotineaminde-ade
nine-dinucleotide. It is a coenzyme and an
electron carrier.
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Draw and label a diagram showing the structure of
a mitochondrion as seen in ELECTRON MICROGRAPHS
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Explain aerobic cellular respiration, including
the link reaction, the Krebs cycle, the electron
transport chain
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Transition Reaction/Pre-Krebs/Link Reaction
Occurs in the Matrix
Each pyruvic acid molecule is broken down to
form CO2 and a two-carbon acetyl group, which
enters the Krebs cycle. An Oxidative
Decarboxylation Reaction
Pyruvic Acid
Acetyl CoA
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General Outline of Aerobic Respiration
Glycolysis
Transition Reaction
Krebs Cycle
Electron Transport System
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Krebs Cycle - (also known as Citric Acid Cycle or
Tricarboxylic Acid Cycle) is a step wise cyclic
process which is used to oxidize the pyruvate
formed during glycolysis into (CO2) and (H2O).
Where? In the Mitochondria What? Uses Acetyl
Co-A to generate ATP, NADH, FADH2, and CO2.
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Krebs Cycle
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General Outline of Aerobic Respiration Contd _-
ETS A series of membrane proteins and coenzymes
that undergo a red-ox reactions that often
produce a chemical gradient that can then be used
to do work
Glycolysis
Krebs Cycle
Electron Transport System
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Electron Transport System another version
Proteincomplex
Intermembranespace
Electroncarrier
Innermitochondrialmembrane
Electronflow
Mitochondrialmatrix
ELECTRON TRANSPORT CHAIN
ATP SYNTHASE
Figure 6.12
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Electron Transport System a 3rd view
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Explain oxidative phosphorylation in terms of
chemiosmosis

• The ETCs basics function is to ease the fall of
  electrons from food to oxygen, breaking a large
  energy drop into series of small steps.
• Chemiosmosis is using H ion in the intermembrane
  space to drive ATP, through the use of an ATP
  synthase (enzyme).
• Collectively ETC and chemiosmosis drive oxidative
  phosphorylation

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Generation of ATP Chemiosmosis
Cells use the energy released by falling
electrons in the ETS to pump H ions across a
membrane Uses the enzyme ATP synthase.
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Overview of Aerobic Respiration