Calvin Cycle

Characteristics of Calvin Cycle Similar to KC because starting material is regeneratedSimilar to KC because starting material is regenerated Anabolic and endergonic, takes place in the stroma of the chloroplastAnabolic and endergonic, takes place in the stroma of the chloroplast C enters as carbon dioxide and leaves as a sugarC enters as carbon dioxide and leaves as a sugar ATP is energy sourceATP is energy source NADPH is reducing agent to the sugarNADPH is reducing agent to the sugar Direct carbohydrate product is G3P, glyceraldehyde 3-phosphate (also known as PGAL)…for one G3P, the Calvin cycle must “spin” 3 times “fixing” 3 carbon dioxide moleculesDirect carbohydrate product is G3P, glyceraldehyde 3-phosphate (also known as PGAL)…for one G3P, the Calvin cycle must “spin” 3 times “fixing” 3 carbon dioxide molecules

3 phases of the Calvin Cycle 1. Carbon Fixation – each CO 2 is attached to ribulose biphosphate (RuBP) by an enzyme called Rubisco  most abundant protein on Earth, making 2 molecules of 3- phosphoglycerate per CO 21. Carbon Fixation – each CO 2 is attached to ribulose biphosphate (RuBP) by an enzyme called Rubisco  most abundant protein on Earth, making 2 molecules of 3- phosphoglycerate per CO 2

2. Reduction –2. Reduction – –Each molecule is phosphorylated via ATP and becomes 1-3-biphosphoglycerate (total here is six! …2/each of the three CO 2 …therefore, requiring 6 ATP) –Next NADPH reduces 1-3- biphosphoglycerate to G3P (6 NADPH making 6 G3P) –Only one G3P exits cycle here

3. Regeneration of CO 2 acceptor RuBP3. Regeneration of CO 2 acceptor RuBP –5 remaining G3P use 3 ATP to rearrange into 3 RuBP –The G3P that exited the Calvin cycle will be used in biosynthesis for glucose and other organic molecules

For one G3P molecule, how many CO 2, ATP, and NADPH molecules are needed?For one G3P molecule, how many CO 2, ATP, and NADPH molecules are needed? –3 CO 2 –9 ATP –6 NADPH

To make a glucose molecule, how many CO2, ATP, and NADPH molecules are necessary?To make a glucose molecule, how many CO2, ATP, and NADPH molecules are necessary? - 6 CO ATP -12 NADPH

Where do the ADP and NADP+ go that have been “recycled” due to the Calvin cycle?Where do the ADP and NADP+ go that have been “recycled” due to the Calvin cycle? –To be used in the light reactions in the thylakoid membranes

The Calvin Cycle

Calvin Cycle Animation U27qYJNU0http:// U27qYJNU0http:// U27qYJNU0http:// U27qYJNU0

Lab 4 Photosynthesis This lab will measure the rate of photosynthesisThis lab will measure the rate of photosynthesis Under normal conditions an excited electron will move through the ETC and reduce _______.Under normal conditions an excited electron will move through the ETC and reduce _______.

Lab 4 Photosynthesis This lab will measure the rate of photosynthesisThis lab will measure the rate of photosynthesis Under normal conditions an excited electron will move through the ETC and reduce NADP+.Under normal conditions an excited electron will move through the ETC and reduce NADP+. What is going to happen in this lab?What is going to happen in this lab?

DPIP What happens as light hits the reaction center?

DPIP The DPIP will be reduced, and it will go from blue to colorless How will we measure the rate of reduction of DPIP?

Tips for Success Be sure to add all materials to each cuvette, except the chloroplastsBe sure to add all materials to each cuvette, except the chloroplasts Add chloroplasts to your blank cuvette and calibrate the spectrophotometerAdd chloroplasts to your blank cuvette and calibrate the spectrophotometer Once the machine has been calibrated, add chloroplasts to one cuvette and immediately take your first reading.Once the machine has been calibrated, add chloroplasts to one cuvette and immediately take your first reading.

Use “kim wipes” to keep cuvettes clean.Use “kim wipes” to keep cuvettes clean. Mix each sample before you read itMix each sample before you read it Orient the cuvettes in the spec the same way each time you read them.Orient the cuvettes in the spec the same way each time you read them. Keep all tubes a constant distance from the light source.Keep all tubes a constant distance from the light source. Remove the “dark” cuvette from the foil before getting each reading.Remove the “dark” cuvette from the foil before getting each reading.

Predict Results: