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					INTRODUCTION TO CELLULAR RESPIRATION

• Introduction: All living organisms need energy
• Respiration: the life process by which organisms
  convert the chemical energy stored in food to a form
  of energy more easily utilized by the cell
• Process of Cell Respiration: a biochemical process
  used by cells to release energy from organic
  molecules (food) such as glucose
   ~this energy is stored in the molecule ATP
   ~ ATP = adenosine triphosphate or A~P~P~P
   ~ the process is controlled by enzymes
      Aerobic Cellular Respiration
• Aerobic = with oxygen
• Occurs in the mitochondria
• The use of oxygen releases more energy per glucose molecule
  than anaerobic = without oxygen
• Uses oxygen but releases carbon dioxide and water
SUMMARY EQUATION:
Breathing and cellular respiration are closely related



                             O2                           BREATHING
                                               CO2


                         Lungs



                       CO2
                                 Bloodstream

                                                     Muscle cells carrying out
                                                O2
                                                         CELLULAR
                                                         RESPIRATION

                                    Sugar + O2  ATP + CO2 + H2O
Both plant and animal cells carry out the final stages of
     cellular respiration in the mitochondria.

                Outer membrane             Intermembrane
                                               Mitochondrion
                                           space




                                            Animal Cells
                      Inner
                      membrane
        Plant Cells


                                 Matrix
  STAGES OF CELLULAR RESPIRATION
• Respiration occurs in three main stages



                     High-energy electrons
                     carried by NADH

        GLYCOLYSIS                           KREBS        ELECTRON
                                             CYCLE        TRANSPORT CHAIN


     Cytoplasmic
     fluid                                           Mitochondrion
          1. Glycolysis: [Glyco=sweet, sugar
                                       lysis = to split]
~process in which one molecule of glucose is broken in half, producing 2
  molecules of pyruvic acid, a 3-carbon compound
~ takes place in cytoplasm
~ makes 2 ATP {part of anaerobic respiration too]
~NO OXYGEN NEEDED
~ 2 molecules of NADH are formed




          Glucose                                               Pyruvic
                                                                acid
                       2. Krebs Cycle
• Each pyruvic acid molecule is        Acetyl CoA
  broken down to form CO2 and a
  two-carbon acetyl group, which
  enters the Krebs cycle [Transition
  phase]
• The Krebs cycle completes the
  oxidation of organic fuel,               KREBS
  generating many NADH and                 CYCLE
  FADH2 molecules
• 2 turns per glucose molecule
• Occurs in mitochondria
• Produces 2 ATP
• 6 NADH & 2 FADH2
     3. Electron Transport Chain
• The electrons from NADH and FADH2 travel
  down the electron transport chain to oxygen
• Oxygen is the final electron acceptor
• Occurs in mitochondria
• Produces 32 ATP
Fermentation is an anaerobic alternative to
           aerobic respiration
• Process operates by means of chemical reactions
  catalyzed by enzymes in cytoplasm of cell
• Primary mode of energy production for some
  bacteria and fungi (yeast)
• use glycolysis alone to produce small amounts of ATP
• Important in production of foods such as cheese,
  buttermilk, yogurt, alcohol, (wine/beer) and bread
• 2 types: 1. alcohol & 2. lactic acid
          Alcoholic Fermentation
      glucose -> pyruvic acid-> 2 ethyl alcohol + 2 CO2
    2ATP
GLYCOLYSIS          FERMENTATION
          Lactic Acid Fermentation
Glucose->pyruvic acid -> 2 lactic acid
      2ATP
   GLYCOLYSIS         FERMENTATION
~ used to make cheese and yogurt
~ in humans during strenuous exercise
  not enough oxygen from blood “oxygen debt”
~ lactic acid accumulates in muscle; leads to fatigue and pain

Both types a of fermentation are considered inefficient , only
  produce 2ATP from glycolysis
                          Electrons carried in NADH

                                                 Electrons carried
                                                  in NADH and
                     Pyruvic
                                                 FADH2
                      acid

Glucose      Glycolysis


 Cytoplasm


                                                 Mitochondrion

				
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posted:4/25/2011
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