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11/5/14
• Notes over Photosynthesis• Complete and turn in ATP lab DUE by EOC• CW/HW on photosynthesis
8.2 Photosynthesis
Pages 222-227
4
More on ATP• Cells Have Enough ATP
To Last For A Few Seconds
• ATP must constantly be made
• ATP Transfers Energy Very Well
• ATP Is NOT Good At Energy Storage
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5
Glucose• Glucose is a monosaccharide
• C6H12O6
• One Molecule of glucose Stores 90 Times More Chemical Energy Than One Molecule of ATP
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Photosynthesis
• Photosynthesis is the process of turning light energy into chemical energy!
Chemical Equation
http://www.youtube.com/watch?v=mpPwmvtDjWw
PhotosynthesisPhotosynthesis occurs in TWO phases.1. Light-dependent reactions2. Light-independent reactions (dark reactions)
Remember the “reactants”…….
1. Carbon Dioxide (CO2)2. Water (H20)3. Energy (sunlight)
Where do the reactants come from?
• CO2 (a gas) is in the atmosphere and enters the plant through small openings on the back of leaves called stomata.
The stomata is where gas exchange occurs. CO2 in; O2 out
Where does everything come from?
• Water (H20) comes from the soil absorbed by the plants roots.
Where does everything come from?
Light energy comes from the sun and is captured by chloroplasts.
Chloroplasts
• Chloroplasts capture light energy and are found mainly in the LEAVES.
!REVIEW!
What are the 3 reactants and how do they get into a plant?1. WATER----The roots2. Carbon Dioxide---The stomata3. Light---The chloroplast.
Is photosynthesis catabolic or anabolic??
What organelle does photosynthesis take place in?
Chloroplast
Inside the chloroplast.
• thylakoids – saclike photosynthetic membranes
• grana – stacks of thylakoids
• stroma – space outside the thylakoids
The spectrum of visible light
Energy from the sun travels to Earth in the form oflight. Sunlight is a mixture of differentwavelengths of light – many of these are visibleto your eyes.
How plants obtain energy
Thylakoids have light-absorbing colored molecules called PIGMENTS
• Chlorophyll a & b = blue/green• Xanthophyll = yellow• Carotenoids = orange/red• Anthocyanin = red/purple
• The most common pigment is chlorophyll, which gives plants their green color.
Plants don’t need green light to make food, so it is reflected – which is why plants are green!
• Plants absorb red and blue light from the sun to make food during photosynthesis
• Plants don’t need green light to make food, so it is reflected – which is why plants are green!
So…the best wavelengths of light for plant growth are red and blue while the worst wavelength of light for plant growth is green.
• Ok… now we have all the reactants….Lets make some SUGAR!!
up!!
The Two Phases of Photosynthesis• Phase I - Light Dependent Reaction
(occurs in the thylakoids)– Light energy is absorbed and TRANSFORMED to
chemical energy (ATP and NADPH molecules)
Rember Chemical energy is ATP!!
23
Light Dependent Reaction
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24
Light Dependent Reaction
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What you NEED to Know!
• At the end of Phase I, the plant has made 1.ATP (energy)2.NADPH (electron carrier)3.O2 (oxygen)
• Phase II – Light Independent Reaction (or the Dark Reaction/Calvin Cycle) (occurs in stroma)– NADPH and ATP that were formed during light
dependent reactions are used to make glucose
How plants transform energy
Calvin Cycle converts carbon dioxide into sugar using the NADPH & ATP energy from the light-dependent reactions.
The enzyme Rubisco also helps!
Light Independent Reaction(The Dark Reaction)
(Calvin Cycle)1.ATP and NADPH contain a high
amount of energy, but are short stores (no longer than a few minutes).
2.So plants use the ATP and NADPH to build GLUCOSE which can be stored for a longer time.
The Calvin Cycle1. Does not require light.2. 6 carbon dioxide molecules are
required from the atmosphere3. ATP & NADPH powers the cycle
Not On FIB write down
• The Enzyme Rubisco helps build the glucose molecule during the Calvin cycle.
Reactants & products1.The Calvin Cycle uses 6 molecules of
CO2 to produce a single 6-Carbon sugar molecule called glucose.
2.Uses for sugars include: form starches & cellulose. When other organisms eat plants, they can also use the energy stored in carbohydrates.
Summary of Photosynthesis
Light Reactions• Inputs:
LightWater
• Outputs: ATP
NADPHOxygen (O2)
OCCURS IN THYLOKOID
Dark reactions (Calvin cycle)• Inputs:
◦ ATP◦ NADPH◦ CO2
• Outputs:◦ Sugars
OCCURS IN THE STROMA
Summary• Light reactions Calvin Cycle
Thylakoid Stroma
Glucose
Let’s review…
Light-d
ep
end
ent
reactio
ns
Lig
ht-
ind
ep
end
ent
react
ions
What materials come into the chloroplast that are used in the
light-dependent reactions?
What material comes into the chloroplast that is used by the
Calvin Cycle?
What material moves out of the chloroplast from the light-
dependent reactions?
What materials move out of the chloroplast from the Calvin Cycle?
What materials move from the light-dependent reactions to the Calvin
Cycle?
What materials move from the Calvin Cycle back to the light-
dependent reactions?
Factors affecting Photosynthesis
● Water - shortage can slow or even stop photosynthesis - plants living in dry areas have a waxy coating to prevent water loss
● Temperature - enzymes used in photosynthesis function best between 0°C and 35°C - high or low temps slow down or stop photosynthesis
● Intensity of light - increasing light intensity increases the rate of photosynthesis - plants eventually reach their maximum rate of photosynthesis
And Now……….
• THE PHOTOSYNTHESIS RAP!• http://www.youtube.com/watch?v=pE82qtKS
SH4&safety_mode=true&persist_safety_mode=1&safe=active
A. chloroplasts
B. Golgi apparatus
C. mitochondria
D. vacuoles
Where in the plant cell does photosynthesis take place?
Cellular Energy
8.2 Formative Questions
Chapter 8
STOP!
• Using the cards provided, at your lab table, assemble the equation for photosynthesis with your lab partner(s).
• On a piece of paper, each person should draw a diagram of a plant showing the typical inputs and outputs of the photosynthetic process with your lab partner (s).
• Write the equation for photosynthesis on the paper as well.
