UNIT 3 DAY 6 CALVIN CYCLE OPENER Sit

UNIT 3 DAY 6 CALVIN CYCLE

OPENER Sit with your light reaction group • What do plants gain most of their biomass from? • What happens in the Calvin Cycle? • Is it spontaneous or non spontaneous? How do you know?

Photosynthesis Equation 1. What two inputs/outputs have we learned about so far? 2. What is their role in the light reactions?

AGENDA • Photosynthesis Part Two: The Calvin Cycle • Turn into box: Winter Break Homework • Homework: Photosynthesis Packet

CALVIN CYCLE So the light reaction occurs in the • Thylakoid Membrane The outputs then go to the • Stroma of the chloroplast The dark reaction (independent reaction) occurs in the • Stroma of the chloroplast The output of the dark reaction is • Sugar (carbon based!)

The Calvin Cycle is a series of chemical reactions.

The Calvin Cycle Three Stages 1. Carbon Fixation 2. Reduction 3. Regeneration

The Calvin Cycle CARBON FIXATION O C O Enzyme=Ribisco Carbon Dioxide 2 PGA C C C Ru. BP (Ribuslose bisphosphate)

The Calvin Cycle REDUCTION C C C PGA ATP NADPH C C C G 3 P

The Calvin Cycle REGENERATION C C C C 12 G 3 P C Atoms C 36 C Carbon 30 from Ru. BP C 6 from. CCO 2 C G 3 P C C 2 G 3 P C 10 G 3 P C C C Used to make Ru. BP C C Used to make glucose C C C C

THE CALVIN CYCLE: 3 PARTS 1. Fixation: • Rubisco combines Ru. Bp with CO 2, forming a six carbon molecule that immediately breaks down into a three carbon PGA 2. Reduction: • PGA reduced by ATP, NADPH, producing HIGHER ENERGY GP 3 (BUT, only one out of every six GP 3 s goes into further anabolic pathways, becoming glucose, etc. ) 3. Regeneration: • 5 carbon Ru. Bp regenerated; requires GP 3 and ATP

THE CALVIN CYCLE, FREE ENERGY AND ENTROPY The light reactions capture free energy from the sun • Stored in ATP and NADPH The stored free energy is used to “walk uphill” in Calvin Cycle: • HIGHER ENERGY, MORE ORDERED sugars are made out of LOWER ENERGY, LESS ORDERED carbon dioxide Two consequences: • Energy (from sun) is stored in sugars • Carbon—the building block of ALL BIOMOLECULES—is made available to living things

TAKE THAT SECOND LAW OF THERMODYNAMICS!!! THE CALVIN CYCLE IS ONE OF LIFE’S VICTORY DANCES IN THE BATTLE AGAINST DEATH, DECAY, CHAOS AND DISORDER

Summarize the Dark Reaction on the same paper you wrote the Light Reaction. • Highlight in • Pink the inputs • Orange the outputs THE CALVIN CYCLE

Light Reactions Calvin Cycle

PHOTORESPIRATION Stomata: pores on leaf • Closed on hot, dry days • • • Limits CO 2 access, reducing photosynthetic yield Less CO 2 more O 2 accumulation Photorespiration instead of photosynthesis Photorespiration: wasteful process that uses ATP and O 2, producing more CO 2 and no sugars

REDUCING PHOTORESPIRATION Separate carbon fixation from Calvin Cycle • C 4 Plants (sugar cane, corn, millet) • Physically separate carbon fixation from Calvin Cycle • Different cells to fix carbon vs. where Carbon Cycle occurs • Store Carbon in 4 C compounds • Different enzyme to capture CO 2 (PEP carboxylase) • Different leaf structure • CAM Plants (cactus, pineapple, vanilla, agaves) • Separate carbon fixation form Calvin Cycle by the time of day • Fix carbon during night • Store Carbon in 4 C compounds • Perform Calvin Cycle during the day

RUBISCO ARTICLE What hypothesis did the scientists have? What was their result? Read with your group • rotate who reads what section. Tell the reader to stop when there is something important to highlight