Final answer:
In photosynthesis, energy carriers like ATP and NADPH are generated during the light-dependent reactions and consumed in the light-independent reactions (Calvin cycle) to synthesize sugars from CO2. The energy carriers cycle between 'full' and 'empty' states as they transfer energy and electrons necessary for the production of carbohydrates.
Step-by-step explanation:
Energy Carriers in Photosynthesis
In photosynthesis, electron carriers, or coenzymes, play a critical role in the transfer of energy. There are two main stages of photosynthesis: the light-dependent reactions and the light-independent reactions (Calvin cycle). During the light-dependent reactions, sunlight is absorbed by chlorophyll, and the energy is used to convert water into oxygen and high-energy carriers, such as ATP and NADPH. These energy carriers are considered "full" as they carry the potential energy to the next stage.
In the light-independent reactions, commonly known as the Calvin cycle, these energy carriers (ATP and NADPH) are used to convert CO2 into carbohydrates. Specifically, ATP provides the energy while NADPH transfers electrons to the carbon compounds that will eventually become sugars. Through the enzyme RuBisCO, CO2 is fixed to RuBP, and after several turns of the cycle, G3P is produced, which can be used to form carbohydrates.
Importantly, both processes are connected as the "empty" energy carriers, ATP and NADPH that have released their energy during the Calvin cycle, return to the light-dependent reactions to be re-energized and thus sustain the cycle of photosynthesis.