The Calvin Cycle and Carbon Reactions

These flashcards cover key concepts and processes related to the Calvin cycle and carbon reactions within photosynthesis.

What is the main function of the Calvin cycle in photosynthesis?

The main function is to convert carbon dioxide and energy into glucose through the rearrangement of carbon molecules.

Where does the Calvin cycle take place?

The Calvin cycle takes place outside of the thylakoid membranes in the stroma of chloroplasts.

What is the starting molecule that combines with carbon dioxide in the Calvin cycle?

The starting molecule is RuBP, which is five carbons long.

What molecule is produced when carbon dioxide combines with RuBP?

A temporary six-carbon molecule is produced when carbon dioxide combines with RuBP.

What happens to the six-carbon molecule after it is formed?

The six-carbon molecule quickly breaks in half into two molecules each containing three carbons.

What are the names of the three-carbon molecules produced from the breakdown of the six-carbon molecule?

The three-carbon molecules are called 3-PGA (3-phosphoglycerate).

What energy sources are required for the rearrangement of carbon molecules in the Calvin cycle?

ATP and NADPH generated from the light reaction are required for the rearrangement of carbon molecules.

What is 1,3-bisphosphoglycerate?

1,3-bisphosphoglycerate is an intermediate molecule formed from the rearrangement of 3-PGA, requiring energy.

What is the final carbon molecule produced in the Calvin cycle that can be converted into glucose?

The final carbon molecule is G3P (glyceraldehyde-3-phosphate).

What happens to some of the G3P produced in the Calvin cycle?

Some G3P is used to form glucose, while some is used to regenerate RuBP.

How many turns of the Calvin cycle are needed to produce one molecule of glucose?

Six turns of the Calvin cycle are needed to produce one molecule of glucose.

What happens to ATP and NADPH after they deliver energy to the Calvin cycle?

They are converted to ADP and NADP+, which return to the light reactions for re-energizing.

What is the role of carbon dioxide in the Calvin cycle?

Carbon dioxide serves as a source of carbon that is transformed to eventually produce glucose.

What process requires energy during the Calvin cycle?

The rearrangements of carbon molecules, particularly from 3-PGA to G3P, require energy.

What is the relationship between the light reactions and the Calvin cycle?

The light reactions generate ATP and NADPH, which provide the energy needed for the Calvin cycle.

What happens to NADP+ after it releases energy in the Calvin cycle?

NADP+ returns to the light reactions to be recharged into NADPH.

What type of reactions occur in the Calvin cycle?

The Calvin cycle consists of carbon reactions that rearrange carbon molecules.

What is the significance of regenerating RuBP in the Calvin cycle?

Regenerating RuBP is crucial for the continuation of the cycle, allowing for the fixation of more CO2.

Why is the Calvin cycle considered a cycle?

It is considered a cycle because it continuously regenerates RuBP while transforming carbon into glucose.

What is the end product of the Calvin cycle?

The end product of the Calvin cycle is glucose.

What do you need to remember about the transformations of carbon in the Calvin cycle?

Each transformation involves rearranging carbon to progressively build towards glucose.