Chapter 8-3 Light Dependent and Light Independent Reactions

I. Light Can be packed in particles called PHOTONS. Each photon has energy packed inside. 1. The shorter the wavelength more energy (E) 2. The longer the wavelength, the less E. wavelength Energy Energy wavelength

C. When a photon of a certain amount of E hits chlorophyll, it transfers the E to electrons (e-) in the chlorophyll.

II. Chlorophyll Two types Chlorophyll A- absorbs light in mostly blue/violet and red wavelengths Chlorophyll B – absorbs light in the blue and red wavelengths. Green light is reflected, which is why plants look green.

When chlorophyll absorbs light’s E, it Passes the E to e- in the chlorophyll that Come from water splitting.

III. Chloroplasts B. Contains chlorophyll A. Organelle where PS takes place in autotrophs B. Contains chlorophyll 1. Captures the E from sunlight. 2. Transfers the E to the electrons (e-) in chlorophyll. 3. They are then called “high energy” electrons

Inside a chloroplast

C. Components of Chloroplast Thylakoid – CONTAINS CHLOROPHYLL!! Light-dependent reactions occur here Granum –single stack of thylakoids Grana- All of the Granum in one Chloroplast Lamellae- Connects the grana Stroma – Region outside the thylakoid NO CHLOROPHYLL!! Reactions of the Calvin Cycle occur here LAMELLAE

PLANT CELL - High Energy Sugar Glucose

IV. Light Dependent Reactions

A. Uses energy from sun to: 1. Make ATP- ( recharged ADP + P from Calvin cycle) used in the Calvin cycle. 2. Create NADPH- from NADP+: NADP+ comes from the Calvin cycle and it’s job is to carry the high energy electrons and the H (from water splitting) to form NADPH- 3. Oxygen gas : waste given off to environment (remember it came from the water splitting)

B. WATER IS SPLIT to produce: 1. Oxygen gas (O2)waste 2. Hydrogen 3. e- a. Both are carried on NADP+ (empty “plus” bus) which turns it into NADPH- b. H atoms go to stroma/calvin and are used to make C6H12O6 c. High energy e- are taken to electron transport chain(ETC) - for cellular respiration.

V. Light Independent (dark) Reactions A. also called Calvin Cycle B. Produces high the energy sugar (glucose) C. Uses ATP and NADPH- (from light reactions) to convert carbon and oxygen atoms from CO2 and H atoms from H2O into glucose. D. Does NOT use light energy-uses E from ATP

VI. Factors that Affect rate of PS A. water = NADPH- If no NADPH- = No Glucose B. Temperature- enzymes sensitive to extreme temperatures. C. Light Intensity: in light = in PS (to a certain point) D. CO2 = Carbon and oxygen atoms needed to make glucose.

Summary Light Dependent Reaction Uses : Water + Light To Make : ATP + NADPH- + (O2 as waste) Light Independent Reaction (Calvin Cycle) Uses: CO2 + ATP + NADPH- To Make: glucose ***GLUCOSE IS MADE DURING DARK REACTIONS NOT LIGHT!!!!