Photosynthesis  Is defined as…  A process by which light energy is converted into chemical energy  Where does this take place?  In the chloroplasts of plant cells

The Basics: Reactants and Products

The main source of energy for all life is….  The SUN  Photosynthesis is the process of converting sunlight into ATP then into organic molecules that store energy.

ATP  How is ATP like money?  It is: Energy currency -- the only form of energy living things can use (spend).  How does ATP release energy?  By breaking the bond between the 2 nd and 3 rd phosphate and becoming ADP.

Autotrophs are… Plants or other organisms that make their own energy from the sun or inorganic compounds (they are producers)  Heterotrophs are consumers that…  Get energy from food by eating plants and animals that eat plants

Where are the stroma and thylakoid space relative to the thylakoid membrane?  The chloroplast contains thylakoids in a fluid-filled space called the stroma.  The thylakoid space is inside the thylakoid and the membrane surrounds it.

Where is chlorophyll located?  On the thylakoid membrane  What is chlorophyll?  A pigment that absorbs and reflects light

What are the three products of photolysis?  1 Oxygen to the atmosphere  2 H+ ions inside the thylakoid membrane  3 Electrons to chlorophyll to replace those lost to the ETC

What frequencies of light are absorbed and reflected by chlorophyll?  Red and blue are absorbed  Green is reflected

What happens to chlorophyll when it absorbs light energy?  It loses excited electrons to the electron transport chain.  How are these electrons replaced?  Photolysis= light splitting water with an enzyme.

Describe the ETC: electron transport chain.  A series of protein molecules embedded on the membrane where each one has a higher attraction for electrons than the previous one.

What happens as the energy is released in each redox reaction?  This energy is used to actively transport H+ ions into the thylakoid space against the gradient.  This builds up a higher concentration of H+ in the thylakoid space.

Are H+ freely permeable to the thylakoid membrane? (can they cross easily?)  No-- they are charged!  How do H+ ions diffuse out of the thylakoid space into the stroma?  Through a transport protein called…  ATP Synthetase

Is the flow of H+ ions through ATP Synthase “energy requiring” or “energy releasing”?  Energy releasing  This energy is used to form ATP

Is the formation of ATP energy requiring or energy releasing?  Energy requiring  Energy is needed to create the bond between the 2 nd and 3 rd phosphate making ATP from ADP + P

What serves as the final electron acceptor at the end of the electron transport chain?  NADP+  What happens to create NADPH?  NADP+ combines with the final e- and H+ from the stroma to make NADPH.  NADPH is used in the next phase.

What three things are needed for the light reactions? What three things are produced in the light reactions?  Needed--Light, water, chlorophyll  Produced--oxygen (to atmosphere), ATP, and NADPH (to dark reactions)

The dark reactions, AKA -- the light independent reactions, are also known as…  The Calvin Cycle  What is carbon fixation and where does the carbon come from?  CO2 from the air is added to a 5 Carbon sugar = this is “carbon fixation”  Glucose is produced

What is NADPH used for?  It carries electrons and H+ ions to the Calvin Cycle.  These are used to build glucose molecules.  What enzyme is key to this process?  Rubisco

Explain the results of the Photosynthesis Lab  What light treatments had the highest and the lowest rate of reaction?  What role did DPIP (blue stuff) play in the photosynthesis reaction?

Now that you know all about photosynthesis..  Don’t forget to hug a tree!  Without photosynthesis, we would not have air to breath or food to eat.  THE END ?