What happens during the Calvin cycle? What is required for it to happen (does it need light? Where does the cycle take place?)
The cycle takes place in the stroma of chloroplast, yes it needs light, it mostly needs CO2, but the calvin cycle is a process that turns CO2 into sugar.
The Calvin cycle is a series of biochemical reactions that occur during photosynthesis, specifically in the stroma of chloroplasts. It occurs after the light-dependent reactions have taken place.
During the Calvin cycle, carbon dioxide (CO2) from the atmosphere is converted into glucose, which is a sugar molecule that can be used by plants for energy. The cycle consists of several steps, including:
1. Carbon Fixation: Three molecules of CO2 combine with three molecules of a 5-carbon sugar called ribulose bisphosphate (RuBP) to form six molecules of a 3-carbon compound called 3-phosphoglycerate (3-PGA).
2. Reduction: ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate) generated in the light-dependent reactions provide energy and electrons to convert the 3-PGA molecules into glyceraldehyde 3-phosphate (G3P), another 3-carbon compound. Some of the G3P is used for glucose production, while some is used to regenerate the starting molecule, RuBP.
3. Regeneration: Five out of every six molecules of G3P formed are used to regenerate three molecules of RuBP. This allows the cycle to continue by accepting new CO2 molecules.
The Calvin cycle does not require direct light to occur. However, it relies on the products of the light-dependent reactions, namely ATP and NADPH, which are generated utilizing light energy. These products provide the energy and reducing power needed to drive the reactions of the Calvin cycle.
In summary, the Calvin cycle is the process by which carbon dioxide is converted into glucose during photosynthesis. It occurs in the stroma of chloroplasts and requires the products of the light-dependent reactions (ATP and NADPH) to proceed.
During the Calvin cycle, also known as the dark reaction or light-independent reaction, plants convert carbon dioxide into glucose. This process takes place in the stroma of the chloroplasts in plant cells.
To understand the Calvin cycle, it is important to first know that it occurs as part of photosynthesis, the process by which plants convert sunlight into chemical energy. Photosynthesis has two main stages: the light-dependent reactions and the light-independent reactions.
The Calvin cycle takes place after the light-dependent reactions and does not directly require light. However, it depends on the products generated during the light-dependent reactions. In the light-dependent reactions, light energy is used to generate ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate). These energy-rich molecules are then used in the Calvin cycle.
The Calvin cycle has three main steps: carbon fixation, reduction, and regeneration. Here's a simplified explanation of each step:
1. Carbon Fixation: In this step, carbon dioxide (CO2) is captured and combined with a 5-carbon compound called ribulose bisphosphate (RuBP) using an enzyme called RuBisCO. The resulting unstable molecule quickly breaks down into two 3-carbon molecules called 3-phosphoglycerate (3-PGA).
2. Reduction: The energy-rich molecules, ATP and NADPH, generated during the light-dependent reactions, are used to convert the 3-PGA into another 3-carbon molecule called glyceraldehyde 3-phosphate (G3P). This conversion involves the transfer of energy and electrons to power the reactions.
3. Regeneration: Some G3P molecules produced in the reduction step are used to regenerate RuBP, the initial 5-carbon compound needed for carbon fixation. This step ensures the continuity of the cycle and the availability of RuBP to capture more carbon dioxide.
The Calvin cycle operates in a cyclical manner, continuously converting carbon dioxide into glucose and other organic molecules. Glucose is eventually used for energy production or stored as starch for later use.
In summary, the Calvin cycle is a light-independent process that occurs in the stroma of chloroplasts. Although it does not directly require light, it relies on the ATP and NADPH generated in the light-dependent reactions. Through a series of steps, carbon dioxide is captured, converted into glucose, and eventually regenerated to sustain the cycle.
From Internet:
There are two stages of Photosynthesis –
Light-dependent reactions – As the name suggests, it requires light and mainly occurs during the daytime.
Light-independent reactions – It is also called the dark reaction or Calvin cycle or C3 cycle. This reaction occurs both in the presence and absence of sunlight.