Photosynthesis Basics Where on the plant?

Sunlight broken up

Photosynthesis Basics Not all light is equal to a plant Pg 207 Green light is worst for photosynthesis reactions, so green light gets reflected (red and blue/violet get absorbed) and we see plants as green (especially the leaves)

Photosynthesis Basics Pg 184

Photosynthesis Basics Chloroplasts

Photosynthesis Basics Pg 184

Remember: Plants do both photosynthesis and cellular respiration Cell Respiration The overall chemical reaction: REACTANTS  PRODUCTS Carbon dioxide + Water + ENERGY  Oxygen + Food (air) (sunlight = photons) (sugars) CO2 + H2O + Photons  O2 + C6H12O6 The “true” equations: 6CO2 + 6H2O + 2 Photons  6O2 + C6H12O6 Photosynthesis: 6O2 + C6H12O6  6CO2 + 6H2O + ATP Cellular Respiration: Photosynthesis is just the reverse of Cellular Respiration Remember: Plants do both photosynthesis and cellular respiration

(Sugars) Both Stages happen in the Chloroplasts (just in different parts)

Stage 1: Light-Dependent Reactions Photons (x2) H2O NADP+ ADP (Light energy) empty Light reactions: In the thylakoid’s membranes O2 NADPH ATP e- full

Light Reactions -When photons strike a molecule of chlorophyll it “excites” a single electron on the thylakoid

Light Reactions -This excited e- proceeds to jump around a bit until it is funneled down to the starting point to a e- transport chain in the thylakoid membrane - this is photon reception area is called Photosystem II

Photosystem II (the photon first reception area) & e- transport chain Notice: Water is broken up in the process of going from PS I to the e-chain; this is how plants make O2 Pg 211

A way to think of the light reactions Pg 227

Webpage animations for Light reactions http://www.science.smith.edu/departments/Biology/Bio231/ltrxn.html http://www.stolaf.edu/people/giannini/flashanimat/metabolism/photosynthesis.swf http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter10/animations.html# http://www.stolaf.edu/people/giannini/biological%20anamations.html

Stage 2: Calvin Cycle (Dark reactions) CO2 NADPH ATP e- full (x18) Calvin Cycle: In the Stroma Of Chloroplast Also known as The “Dark Reactions” Sugars NADP+ ADP empty Ex: Glucose Sucrose (x18)

Pg 229

The 2 G3P are the basic units for making sugar molecules like glucose Calvin Cycle: See Pg 229 of textbook Calvin Cycle requires 3 turns (with 3 CO2 total) for one G3P to be made, so with the full six turns we make 2 G3P P C C C (x 6) O C P C C C The used ADP and empty NADP+ that make this reaction work are recycled back to the light reactions + C P OR Glucose The 2 G3P are the basic units for making sugar molecules like glucose

Plants also store excess sugar by reorganizing it as starch. Some is stored as starch in chloroplasts or in storage cells in roots (potato), tubers, seeds (corn), and fruits. Heterotrophs, including humans, may completely or partially consume plants for fuel and raw materials. On a global scale, photosynthesis is the most important process to the welfare of life on Earth. Each year photosynthesis synthesizes 175 billion tons of carbohydrates.