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Chapter 9 Cellular Respiration

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					   Chapter 9 Cellular Respiration
• Food is the source of our energy but how do we
  get access to that energy?

• Energy is measured in calories
                Calories

• Calorie on food labels is
  1000 calories (kilocalorie)

• 1 calorie=amount of energy
  needed to heat 1gram of
  water 1 C
           Cellular Respiration
•    C6H12O6 + 6O2 6CO2 + 6 H20 + energy

•    3 stages to capturing energy in food and
     making ATP
    1. Glycolysis
    2. Krebs cycle
    3. Electron transport
            Glycolysis
        occurs in cytoplasm
• -occurs when oxygen is present
• Glucose is broken into 2 3-C compounds
  (pyruvic acid)
• Invest 2 ATP, get 4 ATP
• Each NAD+ electron carrier NAD+NADH

• Total= 2 ATP, 2 NADH
              Fermentation
    -occurs when no oxygen is present

•   NADHNAD+ (sent back to glycolysis)

•   2 kinds of fermentation
           Alcoholic Fermentation
•   Occurs in making beer, wine, bread

    –   Pyruvic acid + NADHalcohol +CO2 + NAD+
          Lactic Acid Fermentation
•   Occurs during muscle use=burning muscles

    –   Pyruvic acid + NADHlactic acid + NAD+
Kreb’s Cycle and Electron Transport
• Occurs in the mitochondria
            Kreb’s cycle
Pyruvic acid is broken down into CO2
 1. 3-C pyruvic acid loses one C to CO2
 2. 2-C (acetyl-CoA) joins a 4-C molecule
    producing 6-C citric acid
 3. 6-C citric acid is broken down to 4-C
    molecule
 4. Releases 2 CO2 and electrons
 5. Cycle starts over
                 Kreb’s cycle
•   For each turn of cycle
•   3 CO2 released (exhalation)
•   1 ATP produced (used by cell)
•   5 pairs of high energy electrons captured
    – 4 NADH produced from NAD+
    – 1 FADH2 produced from FAD
• What are the electrons used for?
            Electron Transport Chain
•    Uses electrons from Kreb’s cycle to convert
     ADPATP
1.   As every 2 electrons travel down the chain, H+
     ions move across the mitochondria’s membrane
2.   This causes a buildup of positive charges inside
     membrane
3.   As H+ move through ATP synthase, the ATP
     synthase spins
4.   This causes ADP to attach a PATP
5.   Each pair of electrons makes 3 ADPATP
6.   Final product is H2O
Electron Transport Chain
   Total energy from 1 glucose
• Glycolysis             2 ATP
• Kreb’s cycle           2 ATP
• Electron Transport
  – 2 NADH(glycolysis)   4 ATP
  – 8 NADH(Kreb’s)       24 ATP
  – 2 FADH2 (Kreb’s)     4 ATP
• Total                  36 ATP
                Put it all together
   • C6H12O6 + 6O2 6CO2 + 6 H20 + energy

                                                     ATP
From Food              From Kreb’s From Electron
                                   Transport Chain
                       Cycle
            From Air
  How efficient is cellular respiration?
• 36 ATP from 1 glucose is only 38%
  of the total energy stored in the
  glucose

• What happens to other 62% of
  energy?
  – Released as heat

				
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