1. Photosynthesis chemical reaction (Remember… conservation of matter and energy) Light + 6 CO2 + 6 H2O  C6H12O6 + 6 O2 + Heat **Remember to look for the flow of hydrogens. 1

2. Purpose of each portion for photosynthesis Reactants Light = Original source of energy Light = Original source of energy CO2 = gains hydrogens to become glucose (sugar) CO2 = gains hydrogens to become glucose (sugar) H20 = break water to release hydrogens to provide electrons, release oxygen as byproduct H20 = break water to release hydrogens to provide electrons, release oxygen as byproductProducts C6H12O6 (glucose) = sugar (food). C6H12O6 (glucose) = sugar (food). O2 = byproduct (not used) O2 = byproduct (not used) Heat = imperfect energy conversion (2 nd law of thermodynamics) Heat = imperfect energy conversion (2 nd law of thermodynamics) 2

3. Photosynthesis - Method of converting sun’s energy into chemical energy usable by cells Autotrophs: self feeders, organisms capable of making their own food Autotrophs: self feeders, organisms capable of making their own food Photoautotrophs: use sun’s energy e.g. plants photosynthesis-makes organic compounds (glucose) from light Photoautotrophs: use sun’s energy e.g. plants photosynthesis-makes organic compounds (glucose) from light Chemoautotrophs: use chemical energy e.g. bacteria that use sulfide or methane chemosynthesis-makes organic compounds from chemical energy contained in sulfide or methane Chemoautotrophs: use chemical energy e.g. bacteria that use sulfide or methane chemosynthesis-makes organic compounds from chemical energy contained in sulfide or methane **** Photosynthesis does not give plants energy. It provides them with the food (glucose) that mitochondria can then use to create energy (ATP). **** Photosynthesis does not give plants energy. It provides them with the food (glucose) that mitochondria can then use to create energy (ATP). 3

4. Autotroph - Plants 4

5. Autotroph - Algae 5

6. Autotroph - Phytoplankton 6

7. Autotroph - Bacteria 7

8. Photosynthesis Photosynthesis takes place in specialized structures inside plant cells called chloroplasts. Chloroplasts are located in the leaves of plants (so that’s where photosynthesis occurs). Photosynthesis takes place in specialized structures inside plant cells called chloroplasts. Chloroplasts are located in the leaves of plants (so that’s where photosynthesis occurs). 8

9. Leaf and Chloroplast structure 9

10. Light absorbing pigments in chloroplast Chlorophyll IS NOT the only light absorbing pigment in plants. It is just the most abundant (which is why chloroplasts (and thus plants) are green). Chlorophyll IS NOT the only light absorbing pigment in plants. It is just the most abundant (which is why chloroplasts (and thus plants) are green). Different pigments are responsible for absorbing different wavelengths of light. Remember ROYGBIV. Different pigments are responsible for absorbing different wavelengths of light. Remember ROYGBIV. Pigments include chlorophyll a, chlorophyll b, carotenoid, among others. Pigments include chlorophyll a, chlorophyll b, carotenoid, among others. If chlorophyll are green, what colors of light do they absorb? If chlorophyll are green, what colors of light do they absorb? 10

11. Chloroplast structure 11

12. Overall Reaction **** Cellular Respiration Equation is exact opposite of photosynthesis equation (minus the sunlight) 6CO 2 + 6 H 2 O + light energy → C 6 H 12 O 6 + 6O 2 Carbohydrate made is glucose Carbohydrate made is glucose Water is split as a source of electrons from hydrogen atoms releasing O 2 as a byproduct Water is split as a source of electrons from hydrogen atoms releasing O 2 as a byproduct Electrons increase potential energy when moved from water to sugar therefore energy is required Electrons increase potential energy when moved from water to sugar therefore energy is required Why does it take 6 carbon dioxide and 6 waters to make 1 glucose (and release 6 oxygen)?? Why does it take 6 carbon dioxide and 6 waters to make 1 glucose (and release 6 oxygen)?? ****To remember this equation, think “what does a plant need and what does it make” ****To remember this equation, think “what does a plant need and what does it make” **** It “needs” CO 2 to turn into glucose, water for electrons, and sunlight. Energy from sunlight breaks water. H + are taken from water and given to CO 2. **** It “needs” CO 2 to turn into glucose, water for electrons, and sunlight. Energy from sunlight breaks water. H + are taken from water and given to CO 2. **** It makes glucose for food and oxygen as a byproduct (waste). Adding H + to CO 2 generates glucose and taking H+ from water generates oxygen. **** It makes glucose for food and oxygen as a byproduct (waste). Adding H + to CO 2 generates glucose and taking H+ from water generates oxygen. 12

13. Chloroplast See the green light being reflected 13

14. Chlorophyll absorbs the blue but reflects the green. 14

15. Light Reactions Overview: ***H 2 0 + Light energy O 2 + ATP + NADPH **This part makes the “batteries” (ATP and NADPH) for making sugar in the next step **** Note that this is where we use water and light as well as make oxygen. What other parts of the photosynthesis equation are not used / made here (so they have to be in next step)? 15

16. **** ELECTRON TRANSPORT CHAIN pumps H+ ions into the thylakoid space and CHEMIOSMOSIS uses this to make ATP using ATP Synthetase 16

17. Pumping the H+ (protons) into a confined space to build up potential energy. See the similarity in structure and function? 17

18. Calvin Cycle (light independent or “dark” reactions) – occurs in stroma ATP and NADPH generated in light reactions used to fuel the reactions which take CO 2 and break it apart, then reassemble the carbons into glucose. ATP and NADPH generated in light reactions used to fuel the reactions which take CO 2 and break it apart, then reassemble the carbons into glucose. (Underline this on handout) Called carbon fixation: taking carbon from an inorganic molecule (atmospheric CO 2 ) and making an organic molecule out of it (glucose) (Underline this on handout) Called carbon fixation: taking carbon from an inorganic molecule (atmospheric CO 2 ) and making an organic molecule out of it (glucose) **** Basically, Calvin Cycle uses products from light reactions to make glucose. **** Basically, Calvin Cycle uses products from light reactions to make glucose. **** Even though this is called the “dark reactions” they still occur mostly during the day. Why? **** Even though this is called the “dark reactions” they still occur mostly during the day. Why? 18

19. Calvin Cycle Overview: **** 6 CO 2 + ATP + NADPH C 6 H 12 O 6 (glucose) + ADP (P) + NADP + **** Note that ATP and NADPH are not in overall equation because they are constantly recycled (ATP ADP + P and NADPH NADP+) 19