Chloroplasts primarily consume carbon dioxide and light energy to produce sugars and other organic molecules. They also utilize ATP and NADPH, which are energy-carrying molecules, in the process.
Energy Sources and Inputs
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Light Energy: Chlorophyll pigments within chloroplasts capture light energy, initiating photosynthesis. This energy powers the conversion of carbon dioxide into sugars. [Source: Chloroplasts have a high concentration of chlorophyll pigments which capture the energy from sunlight and convert it to chemical energy and release oxygen. The chemical energy created is then used to make sugar and other organic molecules from carbon dioxide in a process called the Calvin cycle. ]
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Carbon Dioxide (CO2): This is a crucial raw material. Chloroplasts incorporate CO2 into organic molecules like glucose during the Calvin cycle. [Source: Chloroplasts have a high concentration of chlorophyll pigments which capture the energy from sunlight and convert it to chemical energy and release oxygen. The chemical energy created is then used to make sugar and other organic molecules from carbon dioxide in a process called the Calvin cycle. ]
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ATP and NADPH: The Calvin cycle, responsible for making sugars, uses ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate) – both high-energy molecules produced during the light-dependent reactions of photosynthesis. For every CO2 molecule fixed, the Calvin cycle consumes three ATP molecules and two NADPH molecules. [Source: To fix one CO2 molecule, three ATP molecules and two NADPH molecules (ATP/NADPH = 1.5) are consumed by the Calvin-Benson-Bassham (CBB) cycle]
Indirect Consumption and Interactions
While not directly consumed, chloroplasts' function is highly dependent on other cellular processes:
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Mitochondrial Activity: The balance between ATP and NADPH in the chloroplast stroma (the inner space) is influenced by mitochondrial activity. A higher capacity for reducing equivalents consumption in mitochondria can indirectly help chloroplasts maintain this crucial energy balance. [Source: A higher capacity of consumption of reducing equivalents in mitochondria can indirectly help chloroplasts to balance the ATP/NADPH ratio in stroma and…]
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Nitrogen Supply: The rate of photosynthesis, and thus the consumption of CO2, can also be affected by nitrogen availability. [Source: It is suggested that large chloroplasts under high N supply is correlated with the decreased Rubisco specific activity and PNUE.]
It's important to note that while some organisms can acquire chloroplasts through a process called kleptoplasty (like sea slugs consuming algae), the chloroplasts themselves don't consume the algae's cells in the traditional sense. The sea slugs consume the algae to obtain the chloroplasts. [Source: The sea slug Elysia timida, however, can steal whole chloroplasts from the cells of the algae it consumes: the stolen structures then become…]
