photosynthesis: the process by which photoautotrophs convert solar energy into stored chemical...

Photosynthesis: the process by which photoautotrophs convert solar energy into stored chemical energy.

6H2O + 6CO2 ----------> C6H12O6+ 6O2

ATP ProductionADP (Adenosine Diphosphate) is similar to ‘drained battery.’ATP (Adenosine Triphosphate) is analogous to ‘charged battery.’

Structure of Chloroplast

Double Membrane

Stroma

Thylakoids

Light-Dependent reaction- occurs in the thylakoid membrane and converts light energy to chemical energy

Light-independent- takes place in the stroma within the chloroplast, and converts CO2 to sugar

Two reactions:

Steps of Light-Dependent Reaction

1. Pigments absorb light and excite electrons that enter electron transport system (moving, charged particles).

2. Light energy splits water (photolysis) yielding H+ (into thylakoid), electrons (electron transport chain) and O2

3. Electrons are transferred to NADP+, creating NADPH (charged battery).

4. H+ flow out of thylakoid through ATP synthase, creating ATP (from ADP).

Light-Dependent reactionMatch #1 - #4 from prior slide

Light-Dependent(Cont.)Input: light energy, ADP and phosphate, NADP+, and water

Output: ATP, NADPH, and Oxygen

in-text, p. 115

sunlight water uptake carbon dioxide uptake

ATP

ADP + Pi

NADPH

NAD+

glucoseP

oxygen release

LIGHT INDEPENDENT-

REACTIONS

LIGHT DEPENDENT-REACTIONS

new water

Light-Independent reactionDoes not require light. ATP and NADPH are used to combine carbon, oxygen (from carbon dioxide) and hydrogen (from NADPH)

Light-Independent (Cont.)

Input: ATP, NADPH, and Carbon Dioxide

Output: ADP and P, NADP+, glucose (or other stored energy)

Calvin-Benson Cycle

In stroma Starts with carbon dioxide fixation- ATP is traded in to make sugar

(Light-Independent)

Carbon dioxide fixation

Fig. 7.15, p. 123

CARBON FIXATION

6 CO2 (from the air)

6 6RuBP

PGA

unstable intermediate

6 ADP

612

12ATP

ATP

NADPH

1012

PGAL

glucoseP

PGAL2

Pi

CALVIN-BENSON CYCLE

12 ADP12 Pi

12NADP+

12