Questions and Answers
Explain the Calvin cycle?
It makes sugar starting from a compound called RuBP, using carbon dioxide, ATP, and NADPH, producing G3P, which is then used to form glucose.
Summarize the overall process of photosynthesis.
6 CO2 + 6 H2O -> C6H12O6 + 6 O2. Light reactions convert light energy to ATP and NADPH, while the Calvin cycle converts CO2 to sugar.
What are the inputs and outputs of the Calvin cycle?
Inputs - carbon dioxide, NADPH, ATP. Outputs - G3P.
Which stage of photosynthesis uses each reactant from the overall photosynthesis equation?
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Which stage generates each product from the overall photosynthesis equation?
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What molecule is the direct product of photosynthesis?
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How is oxygen used by plant cells?
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Photosynthesis provides oxygen, but after that what happens?
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The reactions of this cycle are called the ___________ because they do NOT depend on light energy directly.
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What do the Calvin reactions not depend on?
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The cycle uses the energy produced by ____________ to synthesize _______ (such as glucose) by reducing CO2.
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CO2 is reduced using the reducing potential of _______ that is also produced by photosynthesis.
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What are the three stages of the Calvin cycle?
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What enzyme catalyzes the first step of the Calvin cycle?
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Where does the Calvin cycle occur?
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Thylakoid lumen is also called?
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Where does oxidation/phosphorylation occur?
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_____ from air is fixed. That is the power of the Calvin cycle.
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To link carbons together, what energy forms are generated?
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_________: carbon fixation getting free carbons and fixing them to a molecule.
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_________: adding reducing power.
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_________: Ribulose 1,5-BP accepts the carbons to fix them.
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What is different about the Glyceraldehyde 3-Phosphate dehydrogenase enzyme in the Calvin reaction compared to glycolysis and gluconeogenesis?
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Can glucose 6-phosphate be used to build polymers?
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What is different about the glucose 1-phosphate built in the Calvin cycle compared to glucose 1-phosphate from the galactose entry to glycolysis?
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What are the molecules produced from the Calvin Cycle?
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Study Notes
Calvin Cycle Overview
- The Calvin cycle is a process that converts carbon dioxide into sugar using inputs from light reactions.
- It starts with ribulose bisphosphate (RuBP) and requires carbon dioxide, ATP, and NADPH.
- The output is G3P (glyceraldehyde 3-phosphate), which can be converted into glucose and other organic molecules.
Inputs and Outputs
- Inputs: Carbon dioxide, ATP, NADPH.
- Outputs: G3P, ADP, NADP+.
Photosynthesis Process
- Overall reaction: 6 CO2 + 6 H2O → C6H12O6 + 6 O2.
- Light reactions occur in thylakoid membranes; they convert light into chemical energy (ATP and NADPH) and produce oxygen.
- The Calvin cycle occurs in the stroma, utilizing ATP and NADPH to synthesize sugars from carbon dioxide.
Phases of the Calvin Cycle
- The cycle consists of three stages: fixation, reduction, and regeneration.
- Fixation: Describes the capture of carbon dioxide and its conversion into a stable intermediate, utilizing rubisco enzyme.
- Reduction: Involves the addition of energy to the fixed carbon, producing G3P as an energy-rich sugar.
- Regeneration: Reforms RuBP to continue the cycle, allowing carbon fixation to happen again.
Enzymes and Locations
- Rubisco is the enzyme catalyzing the first step of the Calvin cycle, adding CO2 to RuBP.
- The Calvin cycle occurs in the stroma of chloroplasts, where it can utilize ATP and NADPH produced during the light reactions.
Energy Requirements
- NADPH and ATP generated in light reactions are essential for the energy needed to link carbon atoms and produce sugars.
- The Calvin cycle does not directly depend on light, hence it's referred to as the dark reactions.
Specific Molecule Relationships
- Oxygen is a direct product of photosynthesis but is not used for energy production; instead, it is a byproduct expelled into the atmosphere.
- The sugars produced serve as raw materials for energy and the synthesis of other organic compounds in the plant.
Differences in Metabolism
- The glyceraldehyde-3-phosphate dehydrogenase enzyme in the Calvin cycle uses NADPH instead of NADH, differing from enzymes in glycolysis and gluconeogenesis.
- The form of glucose produced via the Calvin cycle is synthesized from carbon dioxide, highlighting the significance of fixing atmospheric carbon.
Additional Information
- Thylakoid space is also known as the thylakoid lumen; oxidation and phosphorylation occur across thylakoid membranes.
- Glucose 6-phosphate produced in the Calvin cycle is not directly used to build polymers; distinctive processes are involved in its utilization.
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Test your knowledge of the Calvin cycle with these flashcards. Dive into the process of how carbon dioxide and energy are transformed into sugar. Perfect for students of biology looking to solidify their understanding of photosynthesis.
