Chapters 8

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Chapters 8 9Photosynthesis Respiration

• Aka Energetics

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TOP
Secondary Consumers
Energy Pyramid
PRIMARY CONSUMERS
PRODUCERS
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• Where do we get all our energy from?
• Ultimately from the Sun
• By what process do we get this energy?

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Photosynthesis

• Process by which green plants or organism with
  chlorophyll, convert light energy into chemical
  energy in the bonds of carbohydrates

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• Autotrophic
• Can transfer energy to produce food can
  synthesize food
• Plants, some bacteria protists
• Heterotrophic
• Must obtain energy from preformed food gotta
  eat food
• Fungus, all animals, some bacteria protists

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What is needed for autotrophs to photosynthesize?

• Carbon dioxide (atmospheric)
• Water (in the soil or air)
• Sunlight (or artificial light source)
• Chlorophyll (present in leaves and sometimes
  stems)
• Enzymes (to regulate the rate of the reaction)

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Experiments that lead to our understanding of
Photosynthesis

• Van Helmont (1600s)
• Experiment w/ potted plant to determine what a
  plant uses to grow.
• Conclusion Water is necessary for plant growth

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In his own words

• I took an earthen pot and in it placed 200 pounds
  of earth which had been dried out in an oven.
  This I moistened with rain water, and in it
  planted a shoot of willow which weighed five
  pounds. When five years had passed the tree
  which grew from it weighed 169 pounds and about
  three ounces. The earthen pot was wetted
  whenever it was necessary with rain or distilled
  water only. It was very large, and was sunk in
  the ground, and had a tin plated iron lid with
  many holes punched in it, which covered the edge
  of the pot to keep air-borne dust from mixing
  with the earth. I did not keep track of the
  weight of the leaves which fell in each of the
  four autumns. Finally, I dried out the earth in
  the pot once more, and found the same 200 pounds,
  less about 2 ounces. Thus, 164 pounds of wood,
  bark, and roots had arisen from water alone."
  (Howe 1965)

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Priestly (1771)

• Experimented w/ candle, plant jar.
• Conclusion Plants produce oxygen that is
  necessary for the candle to stay lit.

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Ingen-Housz (1779)

• Repeated Priestlys experiment but put plant in
  darkness with candle.
• Conclusion Light is needed for photosynthesis
  oxygen production.

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General formula for Photosynthesis

• CO2 H2O (w/chlorophyll enzymes) light
• C6H12O6 O2 H2O

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This process actually occurs in 80 chemical
reactions
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Where in a plant does photosynthesis occur?

• Chloroplasts contain the pigment chlorophyll
• Chloroplasts are oval structures consisting of
  stacked grana (photosynthetic membranes)
• and a liquid called stroma. Chlorophyll is found
  in the stacked grana

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Pigments

• Main photosynthetic pigments are chlorophyll a
  and chlorophyll b
• Other pigments in plastids are accessory pigments
  to absorb all the wavelengths of light

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So what is light?

• White light
• Color depends of which wavelength is being
  reflected.
• So if a leaf is green, green light or wavelengths
  are being reflected and all other colors are
  being absorbed. If black, all the wavelengths (or
  colors) are being absorbed, reflecting nothing.
  
• Absorbed wavelengths become energy (heat or
  kinetic).

is a mixture of all the wavelengths (colors) of
visible
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Is all light the same?

• Using a spectroscope, we will look at different
  light sources
• Sunlight,
• Incandescent light
• Fluorescent light
• Fluorescent light
• Incandescent light

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Plants just love red and blue light. They dont
utilize much green or yellow
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Why do leaves change color in the fall?

• Since chlorophyll a b are the densest pigments,
  they break down first when water is sparse.
• This leaves the other pigments like the
  carotenoids, cyanins and xanthophylls to remain
  longer until they break down.

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What happens to the energy absorbed by the
chlorophyll of the plants?

• The energy will be stored in the bonds of
  Adenosine Triphosphate (ATP).
• Animation

Adenine
3 phosphate groups
Ribose
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• ATP is made up of adenine, ribose, and three
  phosphate groups.
• ATP acts as temporary energy storage.
• You make and break down ATP molecules constantly.
• ADP P ATP
• Think of ATP like cash in your pocket
• Glucose like an ATM card
• Glycogen like your savings account
• Lipids like a Savings Bond

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Photosynthesis occurs in 2 major steps

• Light Reaction
• occurs only in the presence of light.
• Occurs in the grana (thylakoids) of the
  chloroplasts
• Also known as Photolysis because light is used to
  split water molecules into hydrogen and oxygen

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Light Dependant Reaction This one is my favorite!
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• 2.Dark Reactions (Light Independent rx)
• can occur in light or darkness. Follows light
  reaction
• Occurs in the stroma of the chloroplasts
• Also known as Carbon fixation because CO2 will
  get fixed up with the hydrogens and energy from
  the light reaction to produce Glucose

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Overview of Photosynthesis
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The Steps in Photosynthesis

• THE LIGHT REACTION
•  1) The light energy strikes the leaf, passes
  into the leaf and hits a chloroplast inside an
  individual cell.
•  2) The light energy, upon entering the
  chloroplasts, is captured by the chlorophyll
  inside a grana. Electrons are excited.
• NADPH ATP are formed
•  3) Inside the grana some of the energy is used
  to split water into hydrogen and oxygen.
•  4) The oxygen is released into the air.

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• THE DARK REACTION Calvin Cycle
• 5) The hydrogen (from NADPH) is taken to the
  stroma along with the grana's remaining light
  energy (ATP).
• 6) Carbon dioxide enters the leaf and passes
  into the chloroplast.
• 7) In the stroma the remaining light energy
  (ATP) is used to combine hydrogen (from NADPH)
  and carbon dioxide to make carbohydrates. This
  occurs during the Calvin Cycle
• 8) The energyrich carbohydrates are carried to
  the plant's cells.
•  9) The energyrich carbohydrates are used by
  the cells to drive the plant's life processes.

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Great Summary of Photosynthesis Respiration

• A good one

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• Chapter 9 Respiration
• aka Getting energy from the cake

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• Think of Photosynthesis like baking a cake.
• The plant takes the raw materials (CO2 H2O),
  puts them together using energy (heat),
  synthesize the cake.
• In order to get the energy out of the cake, the
  plant us must ingest it (eat), digest it (break
  it down into its monomers) then we must burn
  it to release the energy stored in the bonds of
  the cake.
• THIS IS RESPIRATION

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• How do we get the energy out of the food that we
  have consumed?

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Cellular Respiration

• Is the process by which organisms obtain the
  energy that they need by releasing the chemical
  energy stored in nutrients
• Nutrient Glucose
• Chemical Energy ATP

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• Occurs in the Mitochondria
• of Eukaryotic organisms

Respiration occurs on the Cristae
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Two Types of Respiration

• Aerobic Respiration needs oxygen to release the
  energy in food
• C6H12O6    6O2    6CO2    6 H2O   36 ATP
• Anaerobic Respiration can release the energy
  from food without the need of oxygen. (Some
  bacteria yeast)
• C6H12O6    2CO2    2 Ethanol    2 ATP
• C6H12O6    2Lactic Acid    2 ATP

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Anaerobic Respiration

• Also known as Fermentation
• Occurs in the cytoplasm of yeast some bacterial
  cells
• Since the organism are very small simple, do
  not need much ATP

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Anaerobic Respiration occurs in two steps

• Glycolysis
• Glucose (6 Carbons) is broken down into 2
  Pyruvic (3 Carbons each) acid molecules 2 ATP
  (activation energy)
• Produces 4 ATP, netting 2 ATP

2 ATP?
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Fermentation

• The 2 Pyruvic Acids will break down into
• 1. Alcohol CO2 (if yeast some bacteria)
• 2. Lactic Acid (some bacteria)
• Both forms will not produce any more ATP molecules

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Uses for Fermentation

• Yeast some bacteria
• Used in baking, wine making brewing industry
• Bacteria
• Lactic acid production is used in cheese
  processing, buttermilk, sour cream, yogurt,
  sauerkraut, pickles. The souring of dairy
  products is actually the production of lactic
  acid by anaerobic bacteria

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Aerobic Respiration

• Occurs in the Mitochondria
• Yields more ATP per molecule of glucose (36 38
  molecules) of ATP/Glucose
• Occurs in 3 basic steps

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• Glycolysis
• Using 2 ATP as activation energy, a glucose
  molecule is broken down into 2 Pyruvic Acid
  molecules. 4 ATP are produced, leaving 2 ATP
  netted Occurs in cytoplasm
• 2. Krebs Cycle in the Mitochondria, the 2
  Pyruvic acids are broken down, releasing CO2
  producing 2 ATP
• 3. Electron Transport Chain Oxygen combines
  with hydrogen
• 32 ATP are produced

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Krebs Cycle
Pyruvic Acid
Carbon Dioxide
2 Carbon Dioxides
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How much more efficient is Aerobic Respiration
than Anaerobic Respiration at releasing ATP from
one molecule of glucose?

• Aerobic respiration yields 2 2 32?36 ATP
• Anaerobic respiration yields 2 ATP ? 2
  ATP _______
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  36 2
• Aerobic Respiration is 18xs more efficient!!!
  

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Muscle Fatigue

• You are a big organism need a lot of ATP to
  keep you fueled.
• At times though, you may not be breathing
  correctly therefore, arent taking in enough O2
  to remain an aerobic organism.
• During this time, your body (muscle cells)
  convert to anaerobic respiration to give you some
  ATP. Hey 2 ATP are better than none!
• Lactic acid accumulates in your muscle cells,
  acid burns the cells, causing you to cramp up
  thus stop your activity breathe normally