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Photosynthesis and Cellular Respiration

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Title: Photosynthesis and Cellular Respiration


1
Photosynthesis and Cellular Respiration
2
Energy and Life
  • Energy the ability to do work
  • Autotrophs use sunlight, CO2 , and water to
  • make their own food (sugars) ? PHOTOSYNTHESIS
  • Heterotrophs cant make their own food, they
    have to eat autotrophs to stay alive!

3
ATP
  • ATP (Adenosine Tri-Phosphate) the energy storage
    molecule used by most organisms
  • It is the usable version of a cells energy
  • ATP gets broken down to release energy in the
    Mitochondria

4
Photosynthesis
  • CO2 H2O Sunlight -----------? C6H12O6 O2
  • Chlorophyll pigment inside the chloroplast that
    absorbs sunlight
  • Light Reactions Convert light energy to ATP
    (during the day)
  • Dark Reactions Convert CO2 H2O to sugars (at
    night)

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6
Light Reactions
  • Light Reactions (Photophosphorylation) Convert
    light energy to ATP (during the day) takes the
    energy in light and the electrons in water to
    make the energy rich molecules ATP and NADPH
  • H20 ADP Pi NADP light ? ATP NADPH
    O2 H

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8
Dark Reactions
  • Dark Reactions (Calvin Benson Cycle) Convert
    CO2 H2O to sugars (at night) takes CO2 from
    the atmosphere and the energy in ATP NADPH to
    create a glucose molecule.
  • 6CO218ATP12NADPH H ?18ADP18 Pi 12NADP 1
    glucose

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10
Cellular Respiration
  • C6H12O6 O2 -----------? CO2 H2O Energy
  • The breakdown of food molecules to release energy
    needed for work.
  • Step 1 Glycolysis converts glucose (6-carbon
    sugar) to pyruvate (2, 3-carbon sugars)
    releases energy ? 2 ATP
  • Step 2 Aerobic Respiration breakdown of
    Pyruvate in the presence of Oxygen ? NO ATP made!
  • Step 3 Krebs Cycle Produces coenzymes (NADH)
    to speed up the last step ? 2 ATP
  • Step 4 Electron Transport Chain Uses the
    coenzymes (NADH) to crank out mass amounts of ATP
    ? 32 ATP!

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12
Total ATP Production
  • CELLULAR RESPIRATION PRODUCES A TOTAL OF 36 ATP
    MOLECULES!

13
Anaerobic Respiration Chemical reactions that
release the energy from foods in the absence of
oxygen (O2)
  • Cells (active muscle cells) or organisms
    (bacteria, yeast) that use this process to get
    their energy needs live on the small amount of
    ATP that is provided by Glycolysis (2 ATP)

14
Anaerobic Respiration
  • Alcoholic Fermentation Converts pyruvate
    (3-carbon sugar) to CO2 and ethanol (alcohol)
  • Bakers use the fermentation of yeast cells to
    make breads ( the CO2 makes the dough rise)
  • Also used industrially in the manufacturing of
    beer wine
  • Ethanol is added to gasoline to make gasohol

15
Anaerobic Respiration
  • Lactic Acid Fermentation converts pyruvate to
    Lactic Acid
  • During strenuous exercise you deplete your
    muscle cells of oxygen so they enter the
    anaerobic cycle
  • Lactic acid is a waste product produced from
    this
  • Lactic acid build up in the muscles causes
    muscle cramping
  • Lactic acid made in the muscles diffuses into
    the bloodstream , then goes to the liver, where
    it is converted back into pyruvate

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17
Aerobic vs. Anaerobic
  • Aerobic vs. Anaerobic Respiration
  • 1. Oxygen required 1. No Oxygen required
  • 2. Produces 36 ATP 2. Produces 2 ATP
  • ATP provided through the complete Aerobic
    breakdown of glucose provides energy for
    activities such as eating, sleeping, exercising,
    STUDYING BIOLOGY!
  • Aerobic Respiration is relatively inefficient !!
    ? 36 ATP is only about half the energy contained
    in a glucose molecule!

18
  • Question Where does the rest of the energy go?
  • Answer Lost as heat

19
Organelles where these events occur...
  • Photosynthesis Occurs in the Chloroplasts
  • Both the Light and Dark reactions
  • Stroma fluid inside chloroplast (Dark
    reactions)
  • Thylakoids individual membrane layer
    (pancake) (Light reactions)
  • Granum (Grana) an entire stack of thylakoids

20
  • Cellular Respiration Occurs in the
    Mitochondria, Cytoplasm
  • Glycolysis occurs in the cytoplasm, products
    get shipped to the Mitochondria
  • Aerobic Respiration Krebs Cycle occurs in the
    Mitochondria Matrix
  • Electron Transport Chain occurs on the Cristae

21
Enzymes Catalysts
22
Key Terms
  • Catalyst A chemical agent that accelerates a
    chemical reaction without being permanently
    changed in the process
  • Enzyme A protein molecule that acts as a
    Biological Catalyst
  • Substrate the molecule that the enzyme binds
    to the molecule that undergoes the reaction

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24
5 Things All Enzymes Have in Common
  • 1. They dont make anything happen that could
    not happen on its own
  • 2. They are NOT permanently altered or used up
    by a reaction (they are re-used)
  • 3. The same enzyme usually works for the forward
    and reverse directions of a reaction
  • 4. All enzymes work on specific substrates
  • 5. Enzymes function to lower the Activation
    Energy of a chemical reaction

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26
Activation Energy
  • Activation Energy The extra energy required to
    destabilize existing chemical bonds and initiate
    a chemical reaction
  • Enzymes increase the rate of reactions by
    lowering the Activation Energy!

27
  • Active Site Pocket on the enzyme in which the
    substrate binds to forming an Enzyme-Substrate
    Complex (lock and key)
  • Products what the substrate is turned into
    after binding to the enzyme gets released

28
Factors That Affect Enzyme Activity
  • 1. Temperature rate increases with temp.
    increase only until the temperature optimum is
    reached maximizes random molecular movement
  • Optimal temp range for most human enzymes
    35-40? C (94-99? F )
  • 2. pH pH optimum pH 4 to 6 pepsin (a
    digestive enzyme) works best at pH 2

29
Factors That Affect Enzyme Activity
  • 3. Ionic Concentration high ion concentrations
    (salt) slow down enzyme activity
  • 4. Cofactors Coenzymes presence of small
    non-protein molecules required for proper enzyme
    catalysis
  • Cofactors inorganic (Zn, Cu, metals)
  • Coenzymes organic (vitamins)

30
Factors That Affect Enzyme Activity
  • 5. Enzyme Inhibitors substance that binds to
    an enzyme and decreases its activity
  • Competitive Inhibition resemble an enzymes
    normal substrate, compete with it for the active
    site, block it
  • Noncompetitive Inhibition binds to another
    part of the enzyme besides the active site
    causes the enzyme to change shape so the active
    site cant bind to the substrate
  • 6. Allosteric Regulation receptor site on some
    part of the enzyme other than the active site
    serve as a chemical on/off switch
    (activator/inhibitor)
  • 7. Feedback Inhibition the product of one
    metabolic pathway can become the inhibitor for
    another

31
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