PHOTOSYNTHESIS energy review:  Definition: The process by which light energy is converted to chemical energy  Autotrophs: Organisms which use light energy to make organic compounds  Heterotrophs: Organisms that must get their energy from food sources instead of sunlight or inorganic substances  ATP: An energy-storing molecule

Leaf Structure  Guard Cells: Change shape to open and close the stomata.  Stomata: Permit plants to exchange oxygen and carbon dioxide. It is the opening between the guard cells. Stomata Guard Cells

Photosynthesis: Pigments  Light is a form of energy  Different wavelengths of light have different amounts of energy  Reflected wavelengths give plants their color.  Types of pigments: –Chlorophyll a and b: absorb mostly red, blue light –Cartenoids: absorb mostly blue and green light

Photosynthesis…the process Structure of the chloroplast. The action we care about takes place in the thykaloids

Photosynthesis…the process The formula: 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 Carbon dioxide water glucose oxygen How…

Photosynthesis…the process Step 1 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 Energy capture: 1. Light striking the thykaloids excites the electrons in chlorophyll, causing them to jump to a higher energy level. 2. Now the electrons are excited! 3. H 2 O is split. The O 2 is released as a gas and the H + ions are taken to the next step…

Photosynthesis…the process Step 2 Electrical Flow: Electrons move through a series of molecules called the electron transport chain 1. H + ions moving through the thykaloid membrane add a P to ADP to make ATP; 2. H + ions also combine with NADP + to form NADPH; 3. ATP and NADPH are stored energy to be used in the next step… 4. Check out the link… 1. 6CO 2 +6H 2 O  C 6 H 12 O 6 + 6O 2

PHOTOSYNTHESIS ATP  Adenosine Triphosphate –A nucleotide with 3 phosphate groups A- P~P~P –Energy is released when the bonds that hold the phosphate groups together are broken A- P~P + P –This new compound, A- P~P, is called ADP

Photosynthesis…the process Step 3 Carbon Cycle: The Calvin Cycle  Where carbon dioxide is “fixed” into a 3 carbon sugar. How??  Carbon dioxide combines with a 5 carbon sugar (RuBP)to form a 6 carbon compound  This compound splits and the phosphate groups from the ATP and NADPH form new 3 carbon sugars. 6CO 2 +6H 2 O  C 6 H 12 O 6 + 6O 2

Photosynthesis…the process Step 4 Linear Carbon Change:  Some of the 3 carbon sugars are used to make more RuBP, starting the cycle over;  some of the 3 carbon sugars are used to make organic compounds ( C 6 H 12 O 6 ) which are stored as sucrose or starch  The organic compounds provide the organism energy for growth and metabolism 6CO 2 +6H 2 O  C 6 H 12 O 6 + 6O 2

Photosynthesis… the process What do you really need to know? 1. In the first step, electrons are excited and water splits, Oxygen is released; 2. In the second step, NADPH and ATP (energy storing compounds) are created; 3. In the third step, carbon dioxide is fixed into a 3 carbon sugar; 4. In the fourth step, C 6 H 12 O 6 is created and stored as starch or sucrose. 6CO 2 +6H 2 O  C 6 H 12 O 6 + 6O 2

Photosynthesis… the process Just a little more… 1. In photosynthesis, the Reactants are: Carbon dioxide and water; 2. The Products are: Glucose and Oxygen