Photosynthesis

includes

of

take place intakes place in uses

to produce to produce

use

Light-dependentreactions

Calvin cycle

Thylakoidmembranes Stroma NADPHATPEnergy from

sunlight

ATP NADPH O2 Chloroplasts High-energysugars

Section 8-3

Concept Map

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6CO2 + 6H2O→C6H12O6 + 6O2

Simplified Concept Map

Summary of Rxns in Chloroplast

6CO2 + 6H2O→C6H12O6 + 6O2

PhotosynthesisChloroplasts: Place where takes place!• Thylakoids – saclike membranes

• Contain photosystems (light-collecting units) that are made up of chlorophyll, other pigments and proteins–Chlorophyll absorbs most visible light

except green, which is reflected• Grana – stacks of thylakoids• Stroma –space around thylakoids - aqueous

6CO2 + 6H2O→C6H12O6 + 6O2

NADP+ (Nicotinamide adenine dinucleotide phosphate)1. Electron Carrier – carries e- from chlorophyll to other

molecules2. Holds 2 e- (electrons) and 1 H+ (hydrogen ion)3. Converts to NADPH by combining with H+

– This conversion traps energy that is used in the calvin cycle (dark reactions)

Hi My Name Is

NADP+ Hi My Name Is

NADP+

HOT ELECTRON!

Light ReactionsSummary: Light Energy from the sun is captured by the chloroplasts and splits apart water molecules and excites electrons. As a result, oxygen NADPH, and ATP are made.

Takes place in…. 3 parts!

1. Photosystem II absorbs light from the sun.

a. the energy splits water molecules into oxygen, H+ ions, and electrons

b. Chlorophylls’ electrons get excited by the light

c. Oxygen leaves the plant into atmosphere

2. The excited electrons move down the electron transport chain to Photosystem I and produce NADPH.a. Electrons combine with NADP+ and H+

found in the cell. This forms NADPH (electron carrier).

3. H+ protons move outside the thylakoid and cause ADP and P to become ATP.

– Because there is a higher concentration of H+ protons in the thylakoid membrane than in the stroma, so the H+ will move out into the stroma

(Diffusion!)– As the H+ protons move into the stroma they release

energy which is converted into the chemical energy stored in ATP.

V. Light-Independent Rxns(Calvin Cycle or Dark Rxns)

Summary: The Calvin Cycle uses the energy in ATP and NADPH (made during the light rxns) to fix carbon into an organic compound called PGAL.

Takes place in: STROMA

1. CO2 diffuses into the cell and combines with RuBP to form PGA.

– 3 molecules of RuBP (5-carbon sugar) are present in the cell

– 1 carbon (from CO2) attaches to each RuBP

– This 6-carbon is unstable and immediately splits in half

– This leaves 3-carbon structures called PGA

Ribulose BiPhosphate

Phosphoglycerate

2. PGA is changed into PGAL– PGA interacts with ATP

and NADPH (from light rxns) resulting in PGAL (new 3-carbon structure)

– The ATP and NADPH are returned to the light rxns as ADP, NADP+ and a phosphate group to be reused

– 1 PGAL leaves the cycle to become glucose

Phosphoglyceraldehyde

3. The PGAL is converted back into RuBP– The remaining

PGAL (3 carbons) rearrange into RuBP (5 carbons) with ATP’s energy

– Cycle starts all over again

Glucose is not made DURING photosynthesis

• PGAL molecules are made, which are built up into carbohydrates (sugars) just after photosynthesis ends.

• What enters the Calvin Cycle?• What is produced by the Calvin Cycle?