Chapter 8: Photosynthesis
8-1 Energy and Life
 Energy – the ability to do work
 Organisms and their cells need a steady supply of energy in order to function
Chemical Energy and ATP
 Adenosine Triphosphate
 ATP
 Energy storing molecules
 Made up of…
 1 adenine
 1 ribose
 3 phosphates
 Adenosine Diphosphate
 ADP
 Cells store energy by bonding a third phosphate group to ADP to make ATP.
 Made up of…
 1 adenine
 1 ribose
 2 phosphates
Using Biochemical Energy
 Cells use energy to…..
 maintain homeostasis
 maintain body warmth
 move cells
 transmit nerve impulses
8-2 Photosynthesis: An Overview
Van Helmont’s Experiment
 In the 1600s, Jan van Helmont wanted to find out if plants grew by taking material
out of the soil
 He determined the mass of a pot of dry soil and a small seedling
 Planted the seedling in the pot, and watered it regularly
 After 5 years the seedling was a small tree and had gained 75kg, but the soil’s mass
was almost unchanged
 Van Helmont concluded that the gain in mass came from water because water was
the only thing he had added
 Although van Helmont did not realize it, carbon dioxide in the air made a major
contribution to the mass of his tree
 In photosynthesis, the carbon in carbon dioxide is used to make glucose
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Priestley Experiment – 100 years later…
 He took a candle, placed a glass jar over it and watched as the flame gradually died
 He thought the flame needed something in the air to keep burning
 He placed a sprig of mint into the jar for a few days
 He found that the candle could be relighted and would remain lighted for a while
 The plant produced the substance required for burning
The Photosynthesis Equation
 Photosynthesis – plants trap the sun’s energy and make glucose
 The equation for photosynthesis is:
 6CO2 + 6H2O → C6H12O6 + 6O2
 Carbon dioxide + water → glucose + oxygen
Light and Pigments
 How do plants capture the energy of sunlight?
 Pigments – light absorbing molecules in plants
 Two main types of chlorophyll
 Chlorophyll a
 Chlorophyll b
 Chlorophyll does not absorb green light waves
 Green light is reflected by leaves which is why plants look green
8-3 The Reactions of Photosynthesis
Inside a Chloroplast
 In plants photosynthesis takes place inside chloroplasts
 Parts of a chloroplast
 Thylakoid – disk-like membrane that contain chlorophyll
 Grana – a stack of thylakoids
 Stroma – liquid surrounding the thylakoids
 Photosynthesis occurs in 2 Phases
1. Light Dependent Reaction
2. Light Independent Reaction
Light Dependent Reactions
 First phase of photosynthesis
 Takes place in thylakoid
 Sunlight strikes chlorophyll molecules in the thylakoid
 Energy in the light is transferred to electrons
 Highly energized electrons pass from chlorophyll to electron transport chain
 Electron Transport Chain – a series of proteins embedded in the thylakoid
membrane
 ADP → ATP
 H2O → H + H + O
 Oxygen leaves the plant and goes out into the atmosphere
 Hydrogen combines with NADP
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 NADP → NADPH
 NADPH – an electron carrier
Light Independent Reactions
 Second phase of photosynthesis
 Does not require light
 Takes place in the stroma
 Also called the Calvin Cycle
 Each glucose molecule made contains 6 carbon atoms
 Only one molecule of CO2 is added to the cycle each time, it takes a total of 6
rounds of the cycle to form 1 glucose
 6CO2 combines with RUBP and makes 12 PGA
 12 PGA combines with ATP and NADPH and makes 12 PGAL
 2 PGAL are used to make 1 glucose C6H12O6
 10 PGAL are used to make more RUBP to keep the reaction going
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Chapter 8: Photosynthesis
8-1 Energy and Life
 Energy –
 Organisms and their cells need a steady supply of energy in order to function
Chemical Energy and ATP
 Adenosine Triphosphate


 Made up of…



 Adenosine Diphosphate

 Cells store energy by bonding a third phosphate group to ADP to make _______
 Made up of…



Using Biochemical Energy
 Cells use energy to…..




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8-2 Photosynthesis: An Overview
Van Helmont’s Experiment
 In the 1600s, Jan van Helmont wanted to find out if plants grew by taking material
out of the soil
 He determined the mass of a pot of dry soil and a small seedling
 Planted the seedling in the pot, and watered it regularly
 After 5 years the seedling was a small tree and had gained _____kg, but the soil’s
mass was almost unchanged
 Van Helmont concluded that the gain in mass came from water because water was
the only thing he had added
 Although van Helmont did not realize it, __________ __________ in the air made a
major contribution to the mass of his tree
 In photosynthesis, the carbon in carbon dioxide is used to make ____________
Priestley Experiment – 100 years later…
 He took a candle, placed a glass jar over it and watched as the flame gradually died
 He reasoned that the flame needed something in the air to keep burning
 He placed a sprig of mint into the jar for a few days
 He found that the candle could be re-lighted and would remain lit for a while
 The plant produced the substance required for burning
The Photosynthesis Equation
 Photosynthesis –
 The equation for photosynthesis is:


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Light and Pigments
 How do plants capture the energy of sunlight?
 Pigments –
 Two main types of chlorophyll


 Chlorophyll does not absorb green light waves
 Green light is ____________ by leaves which is why plants look green
8-3 The Reactions of Photosynthesis
Inside a Chloroplast
 In plants photosynthesis takes place inside chloroplasts
 Parts of a chloroplast
 Thylakoid –
 Grana –
 Stroma –
 Photosynthesis occurs in 2 Phases
1. Light Dependent Reaction
2. Light Independent Reaction
Light Dependent Reactions
 First phase of photosynthesis
 Takes place in _______________
 Sunlight strikes ________________ molecules in the thylakoid
 Energy in the light is transferred to electrons
 Highly energized electrons pass from chlorophyll to electron transport chain
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 Electron Transport Chain –
 ______ → ______
 ______ → ___ + ___ + ___
 Oxygen leaves the plant and goes out into the _______________
 Hydrogen combines with NADP
 NADP → __________
 NADPH –
Light Independent Reactions
 Second phase of photosynthesis
 Does not require ___________
 Takes place in the ___________
 Also called the __________ ___________
 Each glucose molecule made contains ______ carbon atoms
 Only one molecule of CO2 is added to the cycle each time, it takes a total of 6
rounds of the cycle to form 1 glucose
 6CO2 combines with RUBP and makes _____ PGA
 12 PGA combines with _______ and __________ and makes _____ PGAL
 _____ PGAL are used to make 1 glucose (C6H12O6)
 _____ PGAL are used to make more RUBP to keep the reaction going
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