15_Photosynthesis (1)
Definition: Process by which plants, some bacteria, and protistans convert sunlight energy into chemical energy, producing glucose and oxygen.
Word Equation: Carbon dioxide + Water -> Glucose + Oxygen.
Chlorophyll Function: Main pigment involved in photosynthesis; absorbs sunlight and initiates the conversion of light energy into chemical energy.
Chlorophyll Variants:
Chlorophyll a: Essential for all photosynthetic organisms.
Accessory Pigments: Include chlorophyll b, c, d, and e (found in algae and protistans), xanthophylls, carotenoids (like beta-carotene).
Function of Leaves: Act as solar collectors filled with photosynthetic cells.
Raw Material Entry: Water and carbon dioxide enter leaf cells.
Products Exit: Sugar and oxygen are released.
Water Transport:
Transported through xylem vessels from the roots to leaves.
Land plants feature stomata for gas exchange, allowing the entry of CO2 and exit of O2 but risking water loss.
Chloroplast Characteristics:
Thylakoids: Flattened sacs where photosynthesis occurs, stacked in grana.
Stroma: Space between grana.
Membrane System: Chloroplasts have three membranes, creating three compartments.
Two Main Stages:
Light Dependent Reactions: Occur in grana; use light energy to produce ATP and NADPH.
Key Processes:
Photophosphorylation: ATP production.
Photolysis: Splitting of water, releasing O2 and providing electrons.
Light Independent Reactions (Calvin Cycle): Occur in stroma; utilize ATP and NADPH to fix carbon dioxide into carbohydrates.
Key Reaction: Carbon dioxide + RuBP forms unstable six-carbon intermediate, which yields GP.
Photoexcitation: Light energy absorbed by chlorophyll excites electrons, leading to photoionization.
Electron Transfer: Electrons travel through an electron transport chain, driven by Photosystem II (PSII) and Photosystem I (PSI).
Z Scheme: Diagrammatic representation of the process indicating energy transfer.
Processes Involved:
Photoionization, electron transfer to NADP+, production of ATP and NADPH.
Mechanism: H+ ions concentrated in the thylakoid compartment create an electrochemical gradient, driving ATP synthesis.
Function: Occurs only in PSI to produce extra ATP without forming NADPH.
Process:
Carbon fixation: CO2 combines with RuBP to ultimately form glucose via GP and GALP.
ATP and NADPH from light-dependent reactions drive the cycle.
Key Factors:
Light Intensity: Directly correlates with the rate of photosynthesis until limited by other factors.
Carbon Dioxide Concentration: Increased availability boosts photosynthesis rate.
Temperature: Enzyme-catalyzed reactions, rising to an optimum then decreasing if temperatures exceed this.
Success of photosynthesis is contingent on environmental factors and the effective functioning of chlorophyll and associated structures.
Definition: Process by which plants, some bacteria, and protistans convert sunlight energy into chemical energy, producing glucose and oxygen.
Word Equation: Carbon dioxide + Water -> Glucose + Oxygen.
Chlorophyll Function: Main pigment involved in photosynthesis; absorbs sunlight and initiates the conversion of light energy into chemical energy.
Chlorophyll Variants:
Chlorophyll a: Essential for all photosynthetic organisms.
Accessory Pigments: Include chlorophyll b, c, d, and e (found in algae and protistans), xanthophylls, carotenoids (like beta-carotene).
Function of Leaves: Act as solar collectors filled with photosynthetic cells.
Raw Material Entry: Water and carbon dioxide enter leaf cells.
Products Exit: Sugar and oxygen are released.
Water Transport:
Transported through xylem vessels from the roots to leaves.
Land plants feature stomata for gas exchange, allowing the entry of CO2 and exit of O2 but risking water loss.
Chloroplast Characteristics:
Thylakoids: Flattened sacs where photosynthesis occurs, stacked in grana.
Stroma: Space between grana.
Membrane System: Chloroplasts have three membranes, creating three compartments.
Two Main Stages:
Light Dependent Reactions: Occur in grana; use light energy to produce ATP and NADPH.
Key Processes:
Photophosphorylation: ATP production.
Photolysis: Splitting of water, releasing O2 and providing electrons.
Light Independent Reactions (Calvin Cycle): Occur in stroma; utilize ATP and NADPH to fix carbon dioxide into carbohydrates.
Key Reaction: Carbon dioxide + RuBP forms unstable six-carbon intermediate, which yields GP.
Photoexcitation: Light energy absorbed by chlorophyll excites electrons, leading to photoionization.
Electron Transfer: Electrons travel through an electron transport chain, driven by Photosystem II (PSII) and Photosystem I (PSI).
Z Scheme: Diagrammatic representation of the process indicating energy transfer.
Processes Involved:
Photoionization, electron transfer to NADP+, production of ATP and NADPH.
Mechanism: H+ ions concentrated in the thylakoid compartment create an electrochemical gradient, driving ATP synthesis.
Function: Occurs only in PSI to produce extra ATP without forming NADPH.
Process:
Carbon fixation: CO2 combines with RuBP to ultimately form glucose via GP and GALP.
ATP and NADPH from light-dependent reactions drive the cycle.
Key Factors:
Light Intensity: Directly correlates with the rate of photosynthesis until limited by other factors.
Carbon Dioxide Concentration: Increased availability boosts photosynthesis rate.
Temperature: Enzyme-catalyzed reactions, rising to an optimum then decreasing if temperatures exceed this.
Success of photosynthesis is contingent on environmental factors and the effective functioning of chlorophyll and associated structures.