I. PhotosynthesisA. 2 Part Process –

1. Light-Dependent Rxns – convert light energy into chemical energy (ATP)- Also called Light Rxns

2. Light-Independent Rxns – uses ATP from light-dependent rxns to produce sugars– Also called the Calvin Cycle and Dark

Rxns

6CO2 + 6H2O→C6H12O6 + 6O2

Summary of Rxns in Chloroplast

6CO2 + 6H2O→C6H12O6 + 6O2

6CO2 + 6H2O→C6H12O6 + 6O2

B. Takes place in chloroplasts… Structure:1. 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 reflected2. Grana – stacks of thylakoids3. Stroma – space/area around thylakoids

6CO2 + 6H2O→C6H12O6 + 6O2

6CO2 + 6H2O→C6H12O6 + 6O2

III. Electron carriers: NADP+ and NADPH

A. NADP+(Nicotinamide adenine dinucleotide

phosphate)1. Electron carrier –transfers electrons2. Holds 2 electrons and H+ (hydrogen ion)3. Combines with H+ to make NADPH

– This conversion traps energy that is used in the dark rxnsNO!

IV. Light-Dependent RxnsA. Require light for energyB. Uses this energy with H2O (water) to produce:

– ATP and NADPH and– oxygen (O2)

C. Takes place in thylakoidsD. Summary of steps:

1. Photosystem II absorbs light from the sun.

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

– Chlorophylls’ electrons get excited by the light

– Oxygen leaves the plant into atmosphere

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

H+ found in the cell» this forms NADPH

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

– As the H+ protons pass through ATP synthase (protein in thylakoid membrane) into the stroma the protein grabs ADP and a P and converts it into ATP

Animations

http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter10/animations.html#

http://faculty.nl.edu/jste/noncyclic_photophosphorylation.htm

http://www.johnkyrk.com/photosynthesis.html

Thursday November 4th1. What occurs at

photosystem I?2. What occurs at photosystem II?

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

A. No light requiredB. Uses energy from ATP and NADPH to produce high-energy sugars

– Sugars can store energy longer than energy molecules

C. Takes place in stromaD. Summary of steps:

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

– 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+

– 1 PGAL leaves the cycle to become glucose

Phosphoglyceraldehyde

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

PGAL rearrange into RuBP with ATP’s energy

– Then it starts all over again

Summary• The Calvin Cycle continually occurs

producing sugars (glucose) and taking CO2 out of the atmosphere.– Plants use sugars for energy and to

build starches and cellulose for growth and development

– Consumers eat plants and use the energy from the sugars

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

Go to Section:

6CO2 + 6H2O→C6H12O6 + 6O2

Simplified Concept Map

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

Go to Section:

6CO2 + 6H2O→C6H12O6 + 6O2

Simplified Concept Map