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Chapter 9 Respiration
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Chapter 9 - Overview
1. SUN
2. LIGHT ENERGY
3. PHOTOSYNTHESIS
5. RESPIRATION
6. ATP (CELL ENERGY)
4. CHEMICAL ENERGY
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Energy Formation in Cells
Organic Compounds Oxygen

ATP
Energy for Life
Carbon Dioxide Water
ADP and P
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What is Respiration?

• The process of respiration is where organisms
  convert chemical energy into cellular energy,
  which is known as ATP.

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Where does it occur?

• In both autotrophs and heterotrophs that depend
  on chemical energy to make ATP.
• The actual process occurs inside a cells
  cytoplasm and the mitochondria.

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What does it need?

1. Carbohydrates, Sugars, Starches (C6H12O6)
2. Oxygen (O2)

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What happens?(respiration equation)
Carbon Dioxide
ATP
Carbohydrates
C6H12O6
6O2
6CO2
6H2O
ENERGY
Oxygen
Water
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How does this happen?

• The process of respiration is divided into
  different stages depending on whether or not
  oxygen is present.
• When oxygen is present more ATP can be made (up
  to 20 times more).

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How does this happen?

• Respiration that uses oxygen is called aerobic.
• Respiration that does not use oxygen is called
  anaerobic or fermentation.

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Stage 1 - Glycolysis

• A 6-carbon molecule of glucose is separated into
  two 3-carbon pyruvate molecules and makes some
  ATP and NADH.
• This process occurs in 4 steps that take place in
  the cytoplasm and does not require oxygen to be
  present.

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Step 1

• Two ATP phosphates are attached to a molecule of
  glucose to form a new 6-carbon compound.

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Step 2

• The 6-carbon compound is split into two 3-carbon
  compounds each with a phosphate each (PGAL).

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Step 3

• A second phosphate is added to each PGAL, this
  time it comes from NAD creating 2 NADHs.

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Step 4

• All of the phosphates are removed to produce 2
  molecules of Pyruvic Acid. 
• Each removed phosphate combines with a molecule
  of ADP to make an ATP. 

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Glycolysis Summary

• 2 ATP were used to start the process.
• 4 ATP were produced from this process.
• This gives a total net yield of 2 ATP.

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A. Aerobic Respiration

• If oxygen is present the pyruvic acid produced
  during glycolysis continues on to aerobic
  respiration.
• Aerobic respiration takes place within the
  mitochondria. 

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How does it work?

• Aerobic Respiration has 2 stages
• Krebs Cycle
• Electron Transport Chain

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i) Krebs Cycle - Step 1

• Acetyl-CoA combines with Oxaloacetic acid to form
  Citric acid and releases coenzyme A .

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i) Krebs Cycle - Step 2

• Carbon Dioxide (CO2) is released from citric acid
  forming a 5-carbon compound.
• Electrons are transferred to NAD making a
  molecule of NADH.

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i) Krebs Cycle - Step 3

• A CO2 is released from the 5-carbon compound
  forming a 4-carbon compound and electrons are
  again transferred to NAD making a NADH.
• Also a molecule of ATP is produced.

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i) Krebs Cycle Step 4

• The 4-carbon compound is changed to a new
  4-carbon compound and FAD is converted to FADH2.

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i) Krebs Cycle Step 5

• The new 4-carbon compound is converted to the
  original Oxaloacetic acid that began the cycle.
• This produces another NADH.

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ii) Electron Transport Chain Step 1

• Electrons donated by NADH and FADH2 pass through
  the electron transport chain.
• The energy from these electrons pumps hydrogen
  out of the inner mitochondria.

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ii) Electron Transport Chain Step 2

• Hydrogen builds up outside and creates a
  concentration gradient.
• Hydrogen diffuses back to the inside by passing
  through carrier proteins, which add a phosphate
  to ADP creating more ATP.

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ii) Electron Transport Chain Step 3

• Hydrogen that reenters the mitochondria combines
  with used up electrons and oxygen to form water
  (H2O).

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B. Anaerobic Respiration

• If oxygen is not present the pyruvate produced
  during glycolysis continues on to anaerobic
  respiration.
• Anaerobic respiration takes place in the
  cytoplasm.

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How does it work?

• Anaerobic Respiration has 2 types
• Lactic Acid Fermentation
• Alcoholic Fermentation

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i) Lactic Acid Fermentation

• Pyruvate is changed to lactate by removing two
  hydrogen.
• This process is by bacteria and fungi to produce
  foods like yogurt and cheese.
• Also used by muscle cells when oxygen is not
  present (called lactic acid build up.)

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ii) Alcoholic Fermentation

• Pyruvate is changed to Ethyl Alcohol by first
  removing CO2 and then 2 hydrogen.
• This process is used by yeast to prepare many
  foods and beverages.
• The release of CO2 causes dough to rise.

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Aerobic versus Anaerobic

• The total amount of energy that a cell can
  harvest depends on the presence or absence of
  oxygen.
• Aerobic (with oxygen) gains 36 ATP.
• Anaerobic (without oxygen) gains 2 ATP.

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Aerobic respiration 36 ATP
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Anaerobic Respiration 2ATP
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Any Questions?

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