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8.2   cell energetics - photosynthesis
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  • 8.2.1 – Draw and label a diagram showing the structure of a chloroplast as seen in electron micrographs.
  • 8.2.1 – Draw and label a diagram showing the structure of a chloroplast as seen in electron micrographs.
  • 8.2.1 – Draw and label a diagram showing the structure of a chloroplast as seen in electron micrographs.
  • 8.2.2 - State that photosynthesis consists of light-dependent and light-independent reactions.These should not be called “light” and “dark” reactions.
  • 8.2.3 - Explain the light-dependent reactions.Include the photoactivation of photosystem II, photolysis of water, electron transport, cyclic and non-cyclic photophosphorylation, photoactivation of photosystem I, and reduction of NADP+.
  • 8.2.3 - Explain the light-dependent reactions.Include the photoactivation of photosystem II, photolysis of water, electron transport, cyclic and non-cyclic photophosphorylation, photoactivation of photosystem I, and reduction of NADP+.
  • 8.2.3 - Explain the light-dependent reactions.Include the photoactivation of photosystem II, photolysis of water, electron transport, cyclic and non-cyclic photophosphorylation, photoactivation of photosystem I, and reduction of NADP+.
  • 8.2.3 - Explain the light-dependent reactions.Include the photoactivation of photosystem II, photolysis of water, electron transport, cyclic and non-cyclic photophosphorylation, photoactivation of photosystem I, and reduction of NADP+.
  • 8.2.3 - Explain the light-dependent reactions.Include the photoactivation of photosystem II, photolysis of water, electron transport, cyclic and non-cyclic photophosphorylation, photoactivation of photosystem I, and reduction of NADP+.
  • 8.2.3 - Explain the light-dependent reactions.Include the photoactivation of photosystem II, photolysis of water, electron transport, cyclic and non-cyclic photophosphorylation, photoactivation of photosystem I, and reduction of NADP+.
  • 8.2.3 - Explain the light-dependent reactions.Include the photoactivation of photosystem II, photolysis of water, electron transport, cyclic and non-cyclic photophosphorylation, photoactivation of photosystem I, and reduction of NADP+.
  • 8.2.3 - Explain the light-dependent reactions.Include the photoactivation of photosystem II, photolysis of water, electron transport, cyclic and non-cyclic photophosphorylation, photoactivation of photosystem I, and reduction of NADP+.
  • 8.2.3 - Explain the light-dependent reactions.Include the photoactivation of photosystem II, photolysis of water, electron transport, cyclic and non-cyclic photophosphorylation, photoactivation of photosystem I, and reduction of NADP+.
  • 8.2.4 - Explain photophosphorylation in terms of chemiosmosis.
  • 8.2.3 - Explain the light-dependent reactions.Include the photoactivation of photosystem II, photolysis of water, electron transport, cyclic and non-cyclic photophosphorylation, photoactivation of photosystem I, and reduction of NADP+.
  • 8.2.4 - Explain photophosphorylation in terms of chemiosmosis.
  • 8.2.3 - Explain the light-dependent reactions.Include the photoactivation of photosystem II, photolysis of water, electron transport, cyclic and non-cyclic photophosphorylation, photoactivation of photosystem I, and reduction of NADP+.
  • 8.2.3 - Explain the light-dependent reactions.Include the photoactivation of photosystem II, photolysis of water, electron transport, cyclic and non-cyclic photophosphorylation, photoactivation of photosystem I, and reduction of NADP+.
  • 8.2.3 - Explain the light-dependent reactions.Include the photoactivation of photosystem II, photolysis of water, electron transport, cyclic and non-cyclic photophosphorylation, photoactivation of photosystem I, and reduction of NADP+.
  • 8.2.3 - Explain the light-dependent reactions.http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/120072/bio13.swf::Photosynthetic%20Electron%20Transport%20and%20ATP%20Synthesis
  • 8.2.5 – Explain the light-independent reactions.Include the roles of ribulosebisphosphate (RuBP) carboxylase, reduction of glycerate 3-phosphate (GP) to triose phosphate (TP), NADPH + H+, ATP, regeneration of RuBP, and subsequent synthesis of more complex carbohydrates.
  • 8.2.5 – Explain the light-independent reactions.Include the roles of ribulosebisphosphate (RuBP) carboxylase, reduction of glycerate 3-phosphate (GP) to triose phosphate (TP), NADPH + H+, ATP, regeneration of RuBP, and subsequent synthesis of more complex carbohydrates.
  • 8.2.5 – Explain the light-independent reactions.Include the roles of ribulosebisphosphate (RuBP) carboxylase, reduction of glycerate 3-phosphate (GP) to triose phosphate (TP), NADPH + H+, ATP, regeneration of RuBP, and subsequent synthesis of more complex carbohydrates.
  • 8.2.5 – Explain the light-independent reactions.Include the roles of ribulosebisphosphate (RuBP) carboxylase, reduction of glycerate 3-phosphate (GP) to triose phosphate (TP), NADPH + H+, ATP, regeneration of RuBP, and subsequent synthesis of more complex carbohydrates.
  • 8.2.5 – Explain the light-independent reactions.Include the roles of ribulosebisphosphate (RuBP) carboxylase, reduction of glycerate 3-phosphate (GP) to triose phosphate (TP), NADPH + H+, ATP, regeneration of RuBP, and subsequent synthesis of more complex carbohydrates.
  • 8.2.5 – Explain the light-independent reactions.http://highered.mcgraw-hill.com/sites/0070960526/student_view0/chapter5/animation_quiz_1.html
  • 8.2.5 – Explain the light-independent reactions.http://www.science.smith.edu/departments/Biology/Bio231/calvin.html
  • 8.2.6 – Explain the relationship between the structure of the chloroplast and its function.Limit this to the large surface area of thylakoids for light absorption, the small space inside thylakoids for accumulation of protons, and the fluid stroma for the enzymes of the Calvin cycle.
  • 8.2.7 – Explain the relationship between the action spectrum and the absorption spectrum of photosynthetic pigments in green plants.A separate spectrum for each pigment (chlorophyll a, chlorophyll b, and so on) is not required.
  • 8.2.7 – Explain the relationship between the action spectrum and the absorption spectrum of photosynthetic pigments in green plants.A separate spectrum for each pigment (chlorophyll a, chlorophyll b, and so on) is not required.
  • 8.2.8 - Explain the concept of limiting factors in photosynthesis, with reference to light intensity, temperature and concentration of carbon dioxide.
  • 8.2.8 - Explain the concept of limiting factors in photosynthesis, with reference to light intensity, temperature and concentration of carbon dioxide.
  • 8.2.8 - Explain the concept of limiting factors in photosynthesis, with reference to light intensity, temperature and concentration of carbon dioxide.
  • 8.2.8 - Explain the concept of limiting factors in photosynthesis, with reference to light intensity, temperature and concentration of carbon dioxide.
  • Topic 8.2 – Cell Energetics - Photosynthesis
  • Topic 8.2 – Cell Energetics - Photosynthesis
  • Topic 8.2 – Cell Energetics - Photosynthesis

8.2   cell energetics - photosynthesis 8.2 cell energetics - photosynthesis Presentation Transcript

  • Option 8.2 – Photosynthesis HL
  • Chloroplast Structure [8.2.1] 8.2.1
  • Chloroplast Structure [8.2.1] 8.2.1
  • Draw and Label Chloroplast [8.2.1] 8.2.1
  • Photosynthesis occurs in two primary steps referred to as the light-dependent & light-independent reactions. 8.2.2
  • Overall, the light-dependent reaction produces ATP and NADPH, which are used by the light-independent reaction. It takes place in the thylakoid membrane in the grana stacks O 2 H2O+ light + H + electrons ATP +NADPH Can occur through one of two ways: We’ll get to - Cyclic photophosphorylation this later - Non-cyclic photophosphorylation 8.2.3
  • The light-dependent reaction consists of two reaction centers called photosystems (PS), which are embedded in the thylakoid membrane. The reaction starts with PSII. 8.2.3
  • Light-Dependent Reaction 1. In the beginning of photosynthesis light photon is absorbed by pigment molecules in PSII 2. The photon is transferred from molecule to molecule until it reaches chlorophyll a in the reaction center 3. The photon energy excites an electron which is captured by the primary acceptor 1 2 3 8.2.3
  • Light-Dependent Reaction 4. Water is split by an enzyme to produce H+, eand O2 (photolysis) 5. Electrons are sent to the chlorophyll a one by one 6. The excited electron is passed out of PSII and to the electron transport chain (ETC) 4 6 5 8.2.3
  • 7. The excited electrons are passed down the ETC, which consists of carrier molecules (plastoquinone, cytochrome complex). 7 8 8. The energy lost as the electron is transported drives chemiosmosis to phosphorylate ADP to ATP. 8.2.3
  • 9. PSI absorbs a photon and transfers the energy to an electron (similar to PSII) which is passed to PSI’s primary electron center. 9 10 10. The low energy electron passed from PSII through the ETC takes the place of the newly excited electron. 8.2.3
  • 11. The high energy electron is passed down a second electron transport chain that involves ferrodoxin. 12 11 12. NADP reductase catalyses the transfer of the electron from ferrodoxin to NADP+. Two electrons are needed to fully reduce NADP+ to NADPH. 8.2.3
  • 8.2.3
  • Light-Dependent Reaction The products of the light-dependent reaction are used by the Calvin Cycle, which takes place in the chlorophyll stroma. 8.2.3
  • Photophosphorylation via Chemiosmosis During the first ETC, energy lost by the electron is used by b6f complex to pump H+ ions into the thylakoid space. This increase the H+ concentration inside the thylakoid, creating a gradient. ATP synthase uses this gradient energy to phosphorylate ADP into ATP. This is chemiosmosis. 8.2.4
  • Review Question 1. Draw and label a diagram of a chloroplast. 2. Outline the light-dependent reaction. 3. Explain photophosphorylation via chemiosmosis (in regards to photosynthesis). 8.2.3
  • Photophosphorylation via Chemiosmosis 8.2.4
  • Cyclic Photophosphorylation occurs when the light-dependent reaction reuses electrons from PSI. Electrons cycle back from the acceptor in PSI back to the cytochrome in the ETC. Occurs when there is plenty of light and an accumulation of NADPH The process produces ATP, but not NADPH, which is useful for the Calvin cycle, which requires more ATP than NADPH. 8.2.3
  • Cyclic Photophosphorylation occurs when the light-dependent reaction reuses electrons from PSI. Electrons cycle back from the acceptor in PSI back to the cytochrome in the ETC. Occurs when there is plenty of light and an accumulation of NADPH The process produces ATP, but not NADPH, which is useful for the Calvin cycle, which requires more ATP than NADPH. 8.2.3
  • Non-Cyclic Photophosphorylation uses both photosystems and produces both ATP and NADPH. Electrons are used to reduce NADP+ and not recycled PEA PEA 8.2.3
  • The light-independent occurs in the stroma of the chloroplast and involves the fixation of CO2 into multi-carbon sugars (glucose) using the Calvin Cycle. Calvin cycle has three stages: 1. Carbon Fixation 2. Reduction 3. Regeneration of RuBP In: CO2 Out: TP 8.2.5
  • Carbon Fixation At the beginning of the Calvin cycle, one CO2 enters at a time and attaches to a 5-carbon sugar ribulose biphosphate (RuBP). However, the resulting 6-carbon product is highly unstable and so splits into two glycerate-3phosphate (GP). 8.2.5
  • Reduction Next, each GP are acted on by ATP and NADPH from the light dependent reaction to form two of a 3-carbon compounds called triose phosphate (TP) aka G3P. Of every six G3P, one will be used in the synthesis of glucose and complex carbohydrates. 8.2.5
  • RuBP Regeneration The remaining five TP/G3P molecules are recycled back into molecules of RuBP using ATP. They are consumed as incoming CO2 continues to come a start the cycle. Overall the entire process consumes 9 ATP, 6 NADPH & 3 CO2 3 molecules of RuBP used to fix carbon 8.2.5
  • 8.2.5
  • http://highered.mcgrawhill.com/sites/0070960526/student_view0/cha pter5/animation_quiz_1.html 8.2.5
  • http://www.science.smith.edu/departments/B iology/Bio231/calvin.html 8.2.5
  • Chloroplast Structure & Function • The thylakoid membrane has a large surface area to maximize absorption of light • The thylakoid space has a small volume (movement of few hydrogen ions will affect concentration • The stroma contains enzymes that enable the Calvin cycle to proceed 8.2.6
  • An absorption spectrum shows how each pigment absorbs different wavelengths of light. An action spectrum shows the rate of photosynthesis at different wavelengths of light. 8.2.7
  • Action vs. Absorption Spectrums The action and absorption spectrums resemble each other for each chlorophyll pigment, but do not match exactly. When one pigment absorbs light, others are as well which also affect the overall rate of photosynthesis. 8.2.7
  • The following are needed for photosynthesis to occur, so altering them will change the photosynthetic rate. • • • • • Chlorophyll Light Carbon Dioxide Water Suitable temperature These are limiting factors. 8.2.8
  • Light Intensity Once the chlorophyll pigments are saturated with light, the photosynthetic rate can no longer increase. Temperature Low temperatures will prevent the photosynthesis from occurring. Too high will denature the proteins involved. 8.2.8
  • CO2 Concentration When the reaction has been saturated with chlorophyll, the rate can not increase. However, it increases up to that point. 8.2.8
  • Limiting Factors Graphs 8.2.8
  • Photosynthesis includes Lightindependent reactions uses Light-dependent reactions uses Light Energy Thylakoid membranes to produce ATP NADPH occurs in occur in Stroma of O2 Chloroplasts ATP NADPH to produce Glucose
  • The Importance of Photosynthesis • 50% of the organic compounds produced by photosynthesis are used for cellular respiration by the plant • The remaining is: – Used to build cellulose cell walls – Stored • In starch granules (some in chloroplast) • In roots, tubers, seeds, fruits • Photosynthesis is responsible for the O2 in our atmosphere. • And for the food we eat. 160 billion metric tons of carbohydrates are produced annually through photosynthesis.
  • 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Review Questions Draw a diagram of a chloroplast. Where in the chloroplast does the light dependent reaction take place? How does the structure of #2 relate to its function? What is the role of chlorophyll pigments in the light-dependent reaction. What is the primary role of photosystem II? How is water photolysed in photosystem II? What happens to the products of photolysis? Where does the e- from psII go and what does it do along the way? What is the role of H+ gradients in the light dependent reactions? What are the products of the light reaction and where do they go? 8.2
  • 8.2.1 8.2.2 8.2.3 8.2.4 8.2.5 8.2.6 Draw and label a diagram showing the structure of a chloroplast as seen in electron micrographs. State that photosynthesis consists of light-dependent and light-independent reactions. Explain the light-dependent reactions. Explain photophosphorylation in terms of chemiosmosis. Explain the light-independent reactions. Explain the relationship between the structure of the chloroplast and its function. 8.2
  • Explain the relationship between the action spectrum 8.2.7 and the absorption spectrum of photosynthetic pigments in green plants. Explain the concept of limiting factors in 8.2.8 photosynthesis, with reference to light intensity, temperature and concentration of carbon dioxide. 8.2