The Calvin Cycle

Why can't the calvin cycle operate in the dark?

1. ATP and NADPH cannot be formed 2. Enzymes that are needed for the Calvin Cycle, like rubisco, cannot be activated 3. The stomates are closed, so there is not enough C02 available

What do the products of photosynthesis provide humans or other animals that eat the plants?

1. Energy 2. Carbon skeleton

*******What do PGAL and other sugar phosphates provide for the plants?

1. Food 2. They supply energy 3. They provide a Carbon Skeleton

In plants, what is much of the three carbon sugar converted to, and where?

1. In the cytoplasm of leaf cells, much of the sugar is converted into 12 carbon disaccharide, sucrose. 2. Starch 3. Amino acids, which become proteins 4. Lipids

What role does light play in the calvin cycle?

1. It provides ATP and NADPH 2. It activates Rubisco and several other enzymes of the cycle

What do the 3 carbon sugars released from the Clavin Cycle produce?

1. Starch 2. Lipids 3. Amino Acids, which become proteins

What happens to the sucrose, that the leaf cell makes?

1. The leaf cell can consume it, or take it up 2. It can send it through the veins of the leaf to the rest of the plant, with energy and carbon skeletons 3. Chloroplast enzymes can convert the sugars to starch

What is the name of the plants that only use the Calvin Cycle to fix carbon dioxide?

C3 plants

What is formed, and what happens to the molecules when ATP and NADPH are used

ADP and NADP+ are formed, and they return to the light reactions

What steps do ATP and what steps do NADPH use?

ATP is used in steps d and b and NADPH issued in step b

What happens in part c?

Enzyme reactions rearrange PGAL, eventually making a 5-carbon sugar phosphate

What happens to the three carbon sugar that is released from 3 turns of the calvin cycle?

Plants can synthesize other compounds, like carbohydrate polymers and amino acids

Whats the final step (part d)?

The final step is using an ATP molecule, you add a second phosphate group to the 5-carbon sugar phosphate to make a 5-carbon sugar biphosphate RuBP

When is starch accumulated, and what happens to the starch at night

The plant accumulates starch in their chloroplast during daylight, at night, the chloroplast breaks down the starch, to supply the plant with energy and carbon skeletons

Where does the Calvin cycle take place?

in the stroma of a chloroplast cell.

Is the Calvin Cycle part of photosynthesis?

Yes, it completes photosynthesis

Whats the first step of the Calvin Cycle, and what is it called?

Carbon dioxided combines with the five carbon sugar phosphate (RuBP) ribulose biphosphate, its known as Carbon Dioxide fixation because it "fixes carbon dioxide into an organic molecule. This produces an unstable six carbon molecule that immediately splits into two molecules of PGA (3 carbon acid phosphoglyceric acid)

What is the name of the enzyme to do carbon fixation (step a)

Rubisco

What happens with three cycles of the Calvin Cycle

Three carbon Dioxides are needed, forming 6 PGALs of which 5 are needed to regenerate RuBP, and the 6th is available for organism maintenance and growth

What happens in part b?

Two enzyme steps reduce PGA into PGAL, which is 3carbon sugar phosphate phosphoglyceraldehyde . This step requires 1 molecule of ATP and one molecule of NADPH per PGA ,molecule

What does the Calvin Cycle do?

Uses the chemical energy from the light reactions to form sugar that organisms use for growth