Photosynthesis: Calvin Cycle | Summary and Q&A

TL;DR

Dark reactions, also known as the Calvin Cycle, are light-independent reactions in photosynthesis that use ATP, NADPH, and carbon dioxide to fix carbon and produce glyceraldehyde 3-phosphate (PGAL) which can be used to build other carbohydrates.

Key Insights

• 🙂 Dark reactions or the Calvin Cycle occur in the stroma of chloroplasts and are light-independent.
• 🙂 ATP and NADPH, produced during the light reactions, are used as fuel in the Calvin Cycle.
• 🏛️ The Calvin Cycle fixes carbon dioxide and produces PGAL, which can be used to build other carbohydrates.
• 🖐️ The enzyme RuBisCo plays a crucial role in facilitating the reactions of the Calvin Cycle.
• 🙂 Dark reactions are also known as the light-independent reactions because they do not require photons.
• ❓ Carbon fixation is the process of converting carbon dioxide into solid structures, such as carbohydrates.
• 🏍️ The Calvin Cycle is a cycle because it continuously reuses most of the PGAL molecules.

Transcript

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Questions & Answers

Q: What are the dark reactions in photosynthesis?

The dark reactions, also known as the Calvin Cycle, are light-independent reactions that take place in the stroma of chloroplasts. They use ATP, NADPH, and carbon dioxide to fix carbon and produce PGAL.

Q: Why are dark reactions called "dark" if they occur during the day?

Dark reactions are called "dark" because they are light-independent and do not require photons. They can occur at the same time as the light reactions during the day.

Q: What is the main product of the Calvin Cycle?

The main product of the Calvin Cycle is glyceraldehyde 3-phosphate (PGAL), which can be used to build other carbohydrates, including glucose.

Q: How is carbon dioxide fixed in the Calvin Cycle?

Carbon dioxide is fixed in the Calvin Cycle when it reacts with ribulose bisphosphate (RuBP), facilitated by the enzyme RuBisCo. This reaction leads to the production of PGAL.

Summary & Key Takeaways

• The dark reactions, or the Calvin Cycle, occur in the stroma of the chloroplasts and are light-independent.

• The reactions involve the use of ATP and NADPH, produced during the light reactions, along with carbon dioxide to fix carbon and produce PGAL.

• PGAL can be used to generate glucose and other carbohydrates.