Harvesting the Energy in Food To Make ATP: Cellular Respiration

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Harvesting the Energy in Food To Make
ATPCellular Respiration

• Mr. G-Dizzles Bio Class
• November 2005

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Laws of Matter and Energy

• Law of the Conservation of Matter
• Matter is neither created nor destroyed The
  amount of matter in the universe is constant
• This is why we must balance chemical equations
• Law of the Conservation of Energy/1st Law of
  Thermodynamics
• Energy is neither created nor destroyed The
  amount of energy in the universe is constant
• 2nd Law of Thermodynamics
• Whenever high quality (concentrated) energy is
  used to do work, some of the energy is converted
  to a lower quality (less-concentrated) form
  usually heat
• In other words, while the quantity of energy does
  not change in the universe (the 1st law of
  thermo), the QUALITY does
• You can not take low quality energy and recycle
  it back into high quality energy!!!

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Laws of Matter and Energy and Their Application
in Daily Life

• How do food chains and food webs demonstrate the
  laws of matter and energy?
• Only 25 of the energy of gasoline actually
  produces motion in a car. Only 5 of the
  electricity of a light bulb actually produces
  light.
• How does the 2nd law explain this?

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Food Chains in Action
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How does a sealed aquarium demonstrate the laws
of matter and energy?
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So Whats Energy Again?

• The ability to do ___________?
• Three main forms of Energy
• Potentialenergy of position or chemical
  arrangement
• Chemical energy of bonds is a type of PE
• Remember you must add energy to break bonds
  (the activation energy) and energy is released
  when bonds form
• Kineticenergy of motion
• Thermalthink of this as heat energy

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Who can explain the energy conversions going on
here? What are the similarities and differences
between the two scenarios?
FIGURE 7-6
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What are the similarities and difference b/w
Energy Conversions in a car and in a cell?
25 efficient
40 efficient
FIGURE 7-7
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Food As Fuel Lab

• How do you measure how much energy a piece of
  food has?
• BURN IT! And see how much of a temperature change
  you can get from a known amount of water
• What are the units of energy in food?
• 1 Calorie The energy needed to raise 1 liter of
  water (1 liter1000ml1000g) 1oC
• 1 Calorie 1000 calories1Kcal
• 1 can of coke200 calories
• Enough to heat one gram of water by 200,000
  degrees Celsius!
• What would happen if the cells of our body
  released too much energy at once?

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FIGURE 7-5
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Cell Respiration Big Picture

• C6H12O6 6O2? 6CO2 6H20 38 ATP
• This process harvests the potential (chemical)
  energy in food (glucose) molecules and converts
  it into the potential (chemical) energy of ATP
• This process happens in number of enzyme
  catalyzed reactions occurring in both the
  cytoplasm and mitochondrion of the cell
• Think of ATP as a battery molecule it is a
  temporary storage place for the energy of the
  glucose molecule and can be called upon to
  release this energy in just the right amounts to
  perform cellular work

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So What is this ATP thing anyway?

• Adenosine Triphosphate
• Ribose sugar attached to 3 phosphate groups
• Potential energy of food is converted into the
  potential energy of the bonds of this molecule
• Negatively charged phosphates right next to each
  other is kinda like a compressed spring
• These are very unstable bonds with a lot of
  potential energy in them!

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(No Transcript)
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When enzymes break off the last phosphate of the
tail and transfer it to another molecule,
energy is released and made available to do
cellular work
FIGURE 7-9
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FIGURE 7-11
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So What Kind of Work Does ATP Power in the Cell?
FIGURE 7-10
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How does breathing relate to cellular respiration?
FIGURE 7-12
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The Key To Cell Respiration is Falling Electrons

• Glucose is made of Carbon Carbon and Carbon
  Hydrogen bonds
• During Cellular Respiration, the glucose molecule
  is ripped apart and the C-H bonds switch
  partners and form new bonds with oxygen instead
• C-H is replaced by C-O and H-O bonds
• As electrons fall toward oxygen in the forming
  of these new bonds, energy is released
• This energy is harvested by the cell and is used
  to add a phosphate onto ADP to form ATP

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FIGURE 7-15
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Big Picture of Cellular Respiration
See A Closer Look ONLINE ACTIVITY
FIGURE 7-16
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STAGE IGLYCOLYSISThe Splitting of Sugar

• Where? In the cytoplasm
• Is oxygen used/needed? NO (anaerobic)
• What goes in? Glucose and 2 ATP
• What comes out?
• 4 ATP molecules (net gain of 2why?)
• 2 molecules of pyruvic acid (goes to next stage)
• Energy rich electrons and a hydrogen ion from
  glucose are transferred to a carrier molecule
  called NAD to form NADH.
• This carrier molecule think of it as a taxi
  for Hydrogen atoms will eventually give up the
  electrons to the ELECTRON TRANSPORT CHAIN and
  this will power the making of ATP!

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FIGURE 7-20
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Stage IIKrebs Cycle

• Where? In the matrix of the mitochondria
• Is oxygen used/needed? YES (aerobic)
• What goes in? Pyruvic acid (in the presence of
  O2)
• What comes out?
• CO2
• NADH/ FADH2
• 2 ATP
• Although some ATP are produced, the main job of
  the Krebs Cycle is to provide electrons for the
  last stage the ETC
• In essence, the Krebs Cycle breaks down the
  pyruvic acid molecules into CO2 and takes some of
  the pyruvic acids electrons and transfers them
  to NAD/FAD

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Krebs Cycle
Dont get bogged down in the details!! What goes
in? What comes out? What is happening in
general?
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Stage IIIElectron Transport/ATP Synthase

• Where? In the inner membrane of the mitochondria
• Is oxygen used/needed? YES (aerobic)
• What goes in? NADH and FADH2
• What comes out?
• 34 ATP are generated
• Oxygen ultimately accepts the electrons at the
  end of the ETC and then combines with a few
  hydrogen ions to create WATER (H2O)
• A series of proteins embedded in the
  mitochondrial membrane transfers electrons from
  one to another down the chain
• With each transfer, the energy level of the
  electrons is gradually lowered (like climbing
  down stairs!)
• The energy from the flow of electrons is used to
  pump H ions out of the mitochondrial matrix into
  the intermembrane space (from low to high
  concentration)
• The flow of the H back into the matrix (from
  high to low concentration!!!!) provides the
  energy that is used to combine ADP and P to
  produce ATP.

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Electron Transport Chain Powering The Creation of
ATP
FIGURE 7-19
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FIGURE 7-3