1. Light reaction Recap 2. Calvin Cycle (dark reaction) Photosynthesis 1. Light reaction Recap 2. Calvin Cycle (dark reaction)

Talk to a Neighbor… Using the following diagram, walk your partner through the 5 steps of the light-dependent reactions

Summary of Part 1: Video clip Using light energy ADP NADP+ H2O changed into ATP NADPH H+ & O2

(Light-Independent Reactions) O2 gas is released as a by-product through the stomata (pores) on the leaf The energy of ATP and NADPH are now used to power Part 2 of photosynthesis: The Calvin Cycle (Light-Independent Reactions)

Part 2: Calvin Cycle aka Light-Independent rxn or Dark rxn Does NOT need light because energy from sun already captured in NADPH & ATP Occurs in stroma

Calvin Cycle uses ATP & NADPH to produce high-energy sugars

Energy taken out of NADPH & ATP & combined w/CO2 & H+ forming C6H12O6

NADP & ADP recycled back to light reaction Glucose can be converted by cells into lipids, proteins, nucleic acids, etc.

Calvin Cycle Video

Factors that affect the rate of photosynthesis? Amount of water & CO2 (reactants) Temperature - too high or low denatures enzymes Intensity of light

Putting it Together…

Review light rxn

Reactants Diagram H2O CO2 Light Chloroplast C6H12O6 Glucose O2 Word Bank H2O Glucose Light -Dependent Chloroplast Thylakoids Grana Calvin Cycle Light O2 Stroma Reactants Products H2O CO2 Light NADP+ ADP + P Light Dependent Reaction Calvin Cycle ATP NADPH Chloroplast C6H12O6 Glucose O2 Products

Summary: Light Dependent Reaction—H2O is broken down and light energy is stored temporarily in energy carriers, ATP and NADPH Calvin Cycle—energy is transferred from ATP and NADPH to the organic compound glucose

Reactants Products

Questions??

What are the reactants for photosynthesis? What are the products?

Where in the chloroplast do light-independent reactions occur? Stroma

Where do the ATP and NADPH used in the Calvin Cycle come from? Light Reactions

What are the 3 factors that affect the rate of photosynthesis?

Where does gas exchange occur on the leaf?

What happens to the O2 produced by the light reactions?

Cornell Summary