The Calvin Cycle

Photorespiration

A metabolic pathway that consumes oxygen, releases carbon dioxide, generates no ATP, and decreases photosynthetic output; generally occurs on hot, dry, bright days, when stomata close and the oxygen concentration in the leaf exceeds that of carbon dioxide.

C4 plants

A plant that prefaces the Calvin cycle with reactions that incorporate CO2 into four-carbon compounds, the end product of which supplies CO2 for the Calvin cycle.

C3 plants

A plant that uses the Calvin cycle for the initial steps that incorporate CO2 into organic material, forming a three-carbon compound as the first stable intermediate; less efficient in hot and dry regions as stomata must remain closed to prevent excessive water loss

Chromatography

A technique that is used to separate the components of a mixture based on the tendency of each component to travel or be drawn across the surface of another material.

ATP and TP

Ribulose bisphosphate is reformed using __________

Rubisco

Ribulose carboxylase, the enzyme that catalyzes the first step of the Calvin cycle (the addition of CO2 to RuBP, or ribulose bisphosphate).

Stomata

Small openings on the underside of a leaf through which oxygen and carbon dioxide can move

1/2 a glucose

how much glucose is produced in one cycle of the calvin cycle?

the order of the calvin cycle (the order in which the proteins are in the cycle based on the time they were produced)

overall, what was discovered by Calvin´s lollipop experiment?

carbon fixation, reduction of GP, and regeneration of RUBP

what are the three steps to the calvin cycle?

carbon fixation

The initial incorporation of carbon into organic compounds.

G3P; TP

_______________ is reduced to ________________ using reduced NADP and ATP

CAM pathway

a water-conserving, carbon-fixing process; CAM plants take in carbon at night and fix it into various organic compounds and release it during the day

Reduction of GP

GP is converted to TP the reduction of NADPH and using the energy provided by ATP

stroma

Light-independent reactions take place in the _________

Rubisco; carboxylation; RuBP

In the light-independent reactions, ___________ catalyses the __________________ of ________________

Regeneration of RuBP

In the process of carbon fixation, RuBP attaches a CO2 to produce a six-carbon molecule, which is then split to produce two molecules of 3-phosphoglycerate. After phosphorylation and reduction produces glyceraldehyde 3-phosphate (G3P), what more needs to happen to complete the Calvin cycle?

Lollipop experiment

Radioactive carbon-14 is added to a 'lollipop' apparatus containing green algae (Chlorella) Light is shone on the apparatus to induce photosynthesis (which will incorporate the carbon-14 into organic compounds) After different periods of time, the algae is killed by running it into a solution of heated alcohol (stops cell metabolism) Dead algal samples are analysed using 2D chromatography, which separates out the different carbon compounds Any radioactive carbon compounds on the chromatogram were then identified using autoradiography (X-ray film exposure) By comparing different periods of light exposure, the order by which carbon compounds are generated was determined Calvin used this information to propose a sequence of events known as the Calvin cycle (light independent reactions)

RuBP; glucose

Triose phosphate is used to regenerate ____________- and produce _____________