Check/Challenge: page 134

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Check/Challenge page 134

1. Carbon skeletons are created or made longer in
   biosynthesis and they are broken down in
   decomposition.
2. The stepwise nature of the reactions of cellular
   respiration is beneficial because it releases the
   available energy slowly over time instead of it
   all being released at once, which would create
   large amounts of wasted energy.

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Check/Challenge page 134

• 3. Glucose is not a direct source of energy
  because oxidizing one molecule of glucose
  releases much more energy than a single reaction
  needs.
• 4. Cell respiration is like a cars engine
  because the engine slowly releases the energy
  available in gasoline, instead of releasing it
  all at once.

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Check/Challenge page 134

1. Without cell respiration, a cell would have no
   energy made available to them in order to do
   work. Without breathing, an organism would have
   no oxygen and would not be able to do any
   activities.

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Check/Challenge page 134

• NADPH involved in photosynthesis provides p
  and e- needed for oxidation in the Calvin cycle.
• NADH involved in respiration reduced in Krebs
  cycle, donates p and e- to oxygen in the final
  stage of respiration (ETS) to form water
  release ATP
• FADH2 involved in respiration reduced in
  Krebs cycle, also reduces oxygen in ETS to form
  water release ATP

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5.3 Glycolysis

1. Glucose is converted into Glucose-6-phosphate, by
   using 2 ATP molecules.
2. Glucose-6-phosphate splits into two 3-carbon
   sugar phosphates.
3. The sugar phosphates are oxidized and rearranged
   to form Pyruvates (or Pyruvic Acids). This
   converts 2 NAD into 2 NADH and 4 ADP into 4 ATP.

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5.3 Glycolysis
Products of Glycolysis, per 1 molecule of Glucose
Substance of Molecules Formed
Pyruvate 2
NADH 2
ATP Net, 2
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5.3 Glycolysis

• Glycolysis in Plants
• Some starch sucrose breaks down into glucose
  enters as stage 1.
• The three-C sugars formed in photosynthesis can
  enter directly into the 3rd step.

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5.3 Glycolysis

• Overall role of glycolysis in all organisms
  (plants animals) synthesis of ATP, NADH,
  pyruvate (used to form carbon skeletons for
  biosynthesis)

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5.3 Glycolysis

• If NO OXYGEN is present
• Cells reverse the oxidation that produced the
  pyruvate (NADH pyruvate ? NAD lactate)
• Lactate a 3 carbon acid molecule
• NAD cycles back to glycolysis which continues to
  provide a small amount of energy
• So, Anaerobic pathway Lactic-acid Fermentation

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5.3 Glycolysis

• If OXYGEN is present
• Pyruvate enters the Krebs cycle (we will see in
  detail soon)

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5.4 Mitochondria Respiration

• Just like in photosynthesis, the ETS is embedded
  in a membrane of a structure called a
  Mitochondria
• Mitochondria cell organelle (or part) in which
  the Krebs cycle ETS occur often called the
  powerhouse of the cell b/c this is where the
  majority of ATP is synthesized.

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5.4 Mitochondria Respiration

• Mitochondria have both an inner membrane outer
  membrane (look similar to cell membranes).
• The inner membrane contains so many enzymes that
  theres more protein molecules than lipids.

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5.4 Mitochondria Respiration

• The inner membrane has lots of folds cristae,
  which contain the many enzmes of ETS ATP
  synthesis.
• The inside fluid-filled space is called the
  matrix, contains many enzymes of Krebs cycle.

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Mitochondria vs. Chloroplasts
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5.5 The Krebs Cycle
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5.5 The Krebs Cycle

• GROOMING
• Pyruvate from Glycolysis is transported into the
  mitochondria.
• A CO2 is removed, resulting in a 2-carbon
  molecule, acetic acid (or acetate).
• NAD is reduced to NADH, and Coenzyme A (CoA)
  bonds to acetate to form Acetyl CoA.

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5.5 The Krebs Cycle

• GROOMING
• Happens in between Glycolysis Krebs Cycle in
  the mitochondria
• Coenzyme A acts like a carrier molecule to bring
  acetate into the cycle.

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5.5 The Krebs Cycle

• 1. CoA combines the acetate with a 4-C acid
  (oxaloacetate) to form citrate.
• CoA is released recycled to carry more acetate.

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5.5 The Krebs Cycle

• 2. A carbon atom from the citrate is oxidized and
  released as CO2 and a molecule of NAD is
  reduced, resulting in a 5-C sugar, ketoglutarate.

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5.5 The Krebs Cycle

• 3. A carbon atom from the ketoglutarate is
  oxidized and released as CO2 and a molecule of
  NAD is reduced again, resulting in a 4-carbon
  sugar.

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5.5 The Krebs Cycle

• 4. The 4 carbon molecule is rearranged oxidized
  , which reduces an NAD, an FAD, and creates a
  molecule of ATP, to form oxaloacetate (which
  starts the cycle).

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Summary of Glycolysis Krebs Cycle
Products Products Products Products
  Location RawMaterials ATP NADH FADH2 Other
Glycolysis Cytoplasm Glucose 2 2 0 2 Pyruvates
"Grooming" Mitochondria Pyruvate 0 2 0 2 Acetyl CoA 2 Carbon dioxide
Krebs Cycle Mitochondrial Matrix Acetyl CoA(also will need oxygen) 2 6 2 4 Carbon Dioxide
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5.6 Electron Transport System

• General Summary
• The NADH FADH2 from glycolysis the Krebs
  cycle carry H atoms to the ETS are used to
  reduce oxygen form water and synthesize ATP.
• ETS consists of enzymes cytochromes other
  types of proteins, embedded in the inner
  mitochondrial membrane.

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5.6 Electron Transport System

• H atoms are separated into e- and p.
• The e- are transferred step by step through the
  system by the cytochromes.
• At each transfer, some energy is released.
• Some of this energy is used to actively pump p
  out of the matrix into the intermembrane space.

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5.6 Electron Transport System

• Some p will diffuse back into the matrix of the
  mitochondria through ATP synthetase.
• The p transfers some energy to the ATPase, which
  then synthesizes ATP from ADP P.
• The final cytochrome (e- acceptor) is an enzyme
  that combines the e- p with O2 to form water.

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5.6 Electron Transport System

• The H from NADH provides enough energy to
  synthesize 3 ATP molecules.
• The H from FADH2 only has enough energy to
  synthesize 2 ATP molecules.

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5.6 Electron Transport System

• ETS Animation

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5.6 Electron Transport System

• Bacteria dont have mitochondria.
• Their ETS is in their cell membranes.
• In some, O2 isnt the final e- acceptor, so
  depending on the e- acceptor, they can produce
  H2S or NH3. (anaerobic respiration).

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5.6 Electron Transport System

• Facultative anaerobes can survive with or
  without O2, and can switch between fermentation
  aerobic respiration
• Obligate anaerobes cannot survive with O2, so
  can only perform fermentation or anaerobic
  respiration
• Obligate aerobes cannot survive long without O2

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5.7 Oxygen, Respiration, Photosynthesis

• Without O2, cells must perform fermentation which
  only releases 2 ATP per glucose molecule.
• As long as O2 is present, we gain more energy
  from our food.
• Humans ( other animals) get their O2 from
  breathing in air, and O2 in the air comes from
  photosynthesis.

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Relating Photosynthesis Cellular Respiration

• Photosynthesis
• 6 CO2 6 H2O ? C6H12O6 6 O2
• Cellular Respiration
• C6H12O6 6 O2 ? 6 CO2 6 H2O
• The products of photosynthesis are the raw
  materials for cell respiration the products of
  cell respiration are the raw materials for
  photosynthesis.

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Relating Photosynthesis Cellular Respiration

• Photosynthesis
• 6 CO2 6 H2O ? C6H12O6 6 O2
• Cellular Respiration
• C6H12O6 6 O2 ? 6 CO2 6 H2O
• Both processes provide carbon skeletons used in
  biosynthesis use an ETS to form ATP, but they
  differ in their energy source.

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Relating Photosynthesis Cellular Respiration

• Respiration Releases chemical energy by reducing
  oxygen to water oxidizing sugars to carbon
  dioxide.
• Photosynthesis Stores chemical energy by
  oxidizing water to oxygen reducing carbon
  dioxide to sugar.