19 Questions
What powers the enzyme complex ATP synthase in photosynthesis?
The flow of H+ from high concentration in the lumen to low concentration in the stroma
What is the primary function of photolysis in photosynthesis?
Resupply electrons to PSII
Which molecule is covalently bonded to RuBP by Rubisco in the carbon fixation phase?
CO2
What is the product of the reduction phase in the Calvin Cycle?
G3P
In photosynthesis, what is the primary role of ATP?
Powering the enzyme complex ATP synthase
Which phase of the Calvin Cycle involves making G3P back into RuBP?
Regeneration phase
What is one of the main functions of G3P produced in photosynthesis?
Make fatty acids, amino acids, and nucleic acids
What happens when electrons flow from high concentration in the lumen to low concentration in the stroma?
ATP is generated
Which component of photosynthesis involves storing energy in chemical bonds by fixing carbon from CO2?
Calvin Cycle
What is the significance of NADPH in photosynthesis?
Acting as an electron carrier during Calvin Cycle reactions
Which of the following is the primary function of photosynthesis?
Transforming light energy into chemical energy
In eukaryotic cells, where does the process of photosynthesis take place?
Chloroplasts
What is the primary role of Photosystem II in the light reactions?
Donating high energy electrons to the electron transport chain
What is the primary function of the cytochrome complex in the electron transport chain?
Pumping hydrogen ions into the thylakoid lumen
What is the role of plastocyanin (PC) in the light reactions?
Donating low energy electrons to Photosystem I
What is the primary function of Photosystem I in the light reactions?
Re-exciting low energy electrons to a high energy level
What is the role of ferredoxin (FD) in the light reactions?
Reducing NADP+ to NADPH
What is the primary role of the proton gradient generated across the thylakoid membrane?
Driving the synthesis of ATP via ATP synthase
What is the final product of the light reactions?
ATP and NADPH
Study Notes
Light Reactions
- H+ flow from high concentration in the lumen to low concentration in the stroma drives ATP synthase, resulting in ATP formation in the stroma (photophosphorylation)
- Electrons leave the light reactions in NADPH, and new electrons are obtained by splitting water through photolysis by PSII
- These low-energy electrons resupply PSII, while the by-products (H+ and oxygen) are useful but not required for photosynthesis
- The role of photolysis is to generate new electrons by splitting water
Electron Transport Chain
- Photosystem II donates high-energy electrons to an electron transport chain (ETC) starting with the high-energy electron carrier PQ
- PQ reduces cytochrome complex, which uses the energy from the electrons to pump hydrogen ions across the membrane into the thylakoid lumen, generating a H+ gradient
- The low-energy electrons are then used to reduce PC, the last step in the ETC
- Photosystem I accepts the low-energy electrons from PC and re-excites them back to a high-energy level
ATP Synthesis
- ATP is formed during the light reactions using the energy generated from the H+ gradient
- ATP synthase is driven by the H+ flow from the lumen to the stroma
Calvin Cycle
- The Calvin Cycle fixes inorganic carbon from CO2 into organic carbon chains, storing energy in chemical bonds
- CO2 is covalently bonded to the 5C molecule RuBP by the enzyme Rubisco, generating two 3C organic molecules in the carbon fixation phase
- The product of the reduction phase is glyceraldehyde-3-phosphate (G3P)
- One G3P is exported while five go to the regeneration phase and are made back into three molecules of RuBP
Photosynthesis and Cellular Respiration
- Photosynthesis transforms light energy into chemical energy, and is part of the carbon cycle synthesizing new carbon backbones from CO2 released during cellular respiration
Chloroplasts and Components
- In eukaryotes (plants and algae), photosynthesis occurs in the chloroplasts, using components in the stroma, thylakoid membranes, and the thylakoid lumen
- The chloroplast has three compartments: stroma, thylakoid membranes, and thylakoid lumen
Test your knowledge on the process of photosynthesis and how it occurs in eukaryotic cells like plants and algae. Learn about the components involved in chloroplasts, thylakoid membranes, and the light reactions using photosystems.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
