Photosynthesis and Cellular Respiration Section 2

Energy in Living SystemsCalvin Cycle

CH 6 pg 120

Photosynthesis and Cellular Respiration Section 2

Factors that Affect Photosynthesis

• Light intensity (Electron Transport Chain)• Carbon dioxide concentration (Calvin Cycle)• Temperature (enzymes)

Photosynthesis and Cellular Respiration Section 2

Producing Sugar (Calvin Cycle)• The first two stages of photosynthesis depend directly on

light to make ATP and NADPH.

• In the final stage of photosynthesis, ATP and NADPH are used to produce energy-storing sugar molecules from the carbon in carbon dioxide.

Photosynthesis and Cellular Respiration Section 2

Photosynthesis and Cellular Respiration Section 2

Calvin Cycle (continuous process)• CO2 diffuses into the stroma

• Carbon Fixation, an enzyme (RuBisCo) adds CO2 to a carbon molecule

• ATP and NADPH use their energy to drive these reactions to create molecules of G3P (3 carbon)– G3P are used to create sugar molecules to store energy for later use

Photosynthesis and Cellular Respiration Section 2

G3P

PGAG3P

RuBP

G3P

Photosynthesis and Cellular Respiration Section 2

Photosynthesis and Cellular Respiration Section 2

Calvin Cycle (for more information)

• More description and explanation of Calvin Cycle are on the following slides.

Photosynthesis and Cellular Respiration Section 2

Calvin Cycle• CO2 diffuses into the stroma

• The enzyme (RuBP) adds CO2 to a 5 carbon molecule

• This occurs several times to make a 6 carbon molecule – splits into 2 – 3 carbon molecules (PGA)

Photosynthesis and Cellular Respiration Section 2

G3P

PGAG3P

RuBP

G3P

Photosynthesis and Cellular Respiration Section 2

• Each of PGA is converted/made into G3P

• One G3P molecule leaves the Calvin Cycle to be used to make carbohydrates

• The remaining G3P molecules are recycled back to the enzyme RuBP and reenters the Calvin Cycle

Photosynthesis and Cellular Respiration Section 2

G3P

PGA

G3P

RuBP

G3P

Photosynthesis and Cellular Respiration Section 2• Each of PGA is converted/made into G3P

– G3P is a molecule with additional phosphate and H+ that were donated by ATP and NADPH

– ADP and NADP are then recycled to the ETC

• One G3P molecule leaves the Calvin Cycle to be used to make carbohydrates

• The remaining G3P molecules are recycled back to the enzyme RuBP and reenters the Calvin Cycle

Photosynthesis and Cellular Respiration Section 2

Relationship