Chapter 8-3 Chapter 8-3

Light DependentLight Dependent and and

Light IndependentLight Independent

ReactionsReactions

I. Basic PhotosynthesisI. Basic Photosynthesis

A. Photosynthesis – the process by which autotrophs use light energy to turn carbon dioxide and water into glucose and oxygen

B. The basic equation for photosynthesis is as follows: 6CO2 + 6H2O C6H12O6 + 6O2

Sunlight

II. Photosynthesis Equation

A. USES: (reactants)A. USES: (reactants)1. 1. 66 Carbon Dioxide molecules(thanks to Carbon Dioxide molecules(thanks to

us) us) 2. 2. 6 6 Water moleculesWater molecules

B. IN THE PRESENCE OF B. IN THE PRESENCE OF 1. Sunlight 1. Sunlight

B. TO MAKE: (products)B. TO MAKE: (products)1. 1. 11 Glucose (for cell) molecule Glucose (for cell) molecule2. 2. 66 Oxygen molecules (given off as waste) Oxygen molecules (given off as waste)

lucky lucky us us

III. ChloroplastsIII. Chloroplasts

A. Organelle where PS takes place in autotrophsA. Organelle where PS takes place in autotrophs

B. Contains B. Contains chlorophyllchlorophyll (pigment that “traps” (pigment that “traps” light)light) 1. Traps the E from sunlight. 1. Traps the E from sunlight. 2. Transfers the E to the electrons (e-) in 2. Transfers the E to the electrons (e-) in

chlorophyll. chlorophyll. 3. They are then called “high energy” 3. They are then called “high energy” electronselectrons

Inside a chloroplast

Components of ChloroplastComponents of Chloroplast ThylakoidThylakoid – Saclike – Saclike

photosynthetic photosynthetic membranes membranes Light-dependent Light-dependent

reactions occur here reactions occur here

GranumGranum –single stack of –single stack of thylakoids thylakoids GranaGrana- All of the Granum - All of the Granum

in one Chloroplastin one Chloroplast

StromaStroma – Region – Region outside the thylakoid outside the thylakoid membranemembrane Reactions of the Reactions of the

Calvin Cycle occur Calvin Cycle occur herehere

C. C. LIGHT DEPENDENT:LIGHT DEPENDENT: reactions reactions take take place in the place in the thylakoid thylakoid membranesmembranes of chloroplast.of chloroplast.

D. D. LIGHT INDEPENDENT LIGHT INDEPENDENT ((dark/Calvindark/Calvin)): : reactions take reactions take place in the place in the stromastroma of chloroplast.of chloroplast.

High Energy Sugar Glucose

PLANT CELL

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IV. Light IV. Light Dependent Dependent ReactionsReactions

A. Requires light and water

B. Takes place in the Thylakoid

C. Uses energy from sun to form:

1. ATP- ( recharged 1. ATP- ( recharged ADP + P from Calvin cycle) used in the Calvin cycle.

2. Create 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. 3. Oxygen gas : waste given off to waste given off to environment environment (remember it came from the water splitting)

D. Water is split to D. Water is split to produce:produce:

1. Oxygen1. Oxygenwastewaste

2. Hydrogen2. Hydrogenused to used to convert convert NADP+ to NADP+ to form NADPH- which form NADPH- which is is used in the e- transport chain.used in the e- transport chain.

III. Light Independent (dark) Reactions

A. also called Calvin CycleA. also called Calvin Cycle

B. B. Produces high energy sugars (glucose)Produces high energy sugars (glucose)

C. Uses ATP and NADPH- (from light C. Uses ATP and NADPH- (from light reactions) to convert CO reactions) to convert CO2 2 (from (from air) into air) into

glucose.glucose.

D. Does not require light-uses E from D. Does not require light-uses E from ATPATP

IV. Factors that Affect rate IV. Factors that Affect rate of PSof PS

A. No water = No NADPHA. No water = No NADPH

If no NADPH = No GlucoseIf no NADPH = No Glucose

B. Temperature- enzymes sensitive B. Temperature- enzymes sensitive to to extreme temperaturesextreme temperatures

C. Light Intensity:C. Light Intensity:

in light = in PS (to a certain in light = in PS (to a certain point)point)

SummarySummary

Light Dependent ReactionLight Dependent ReactionUses: Water + LightTo 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!!!!