1. What is photosynthesis? Why is the sun important? During photosynthesis (PSN), light energy CONVERTED TO chemical energy. carbon dioxide + water  glucose + oxygen Most of the energy on Earth comes from the SUN! Where does other energy on Earth come from?

1. Autotrophs vs. Heterotrophs most use PSN convert light energy (sun) to chemical energy (stored in starch and cellulose) Heterotrophs have to eat eat autotrophs and/or heterotrophs All life ultimately depends on autotrophs.

1. Photosynthetic organisms plants, algae, cyanobacteria Endosymbiotic Theory chloroplasts and mitochondria were small prokaryotes (free-living bacteria) engulfed (endocytosis) by larger prokaryotes organelles (double membrane) were formed

2. What is a biochemical pathway? complex series of reactions product of one reaction is consumed in the next reaction link between PSN and cellular respiration (CR)

3. Equation for photosynthesis

What are stomata and why are they important to plants? ATP synthase is a multifunctional protein

4. What are chloroplasts? Chloroplasts cell organelle site of PSN (light absorbed here) found in plants and some unicellular eukaryotes (algae) range in size, number (1 large in algae, 50 small in plant cell)

4. Diagram and structure Outside Inside TWO membranes (phospholipid bilayers) endosymbiosis Inside thylakoids system of membranes (phospholipid bilayer as well) arranged as flattened sacs grana = stacks of thylakoids (singular = granum) stroma solution (goo) that surrounds thylakoids

4. Pigment Chlorophylls located in thylakoid membrane chlorophyll a and chlorophyll b chlorophyll a – directly involved in photosynthesis chlorophyll b – assists chlorophyll a both allow green light to be reflected and transmitted carotenoids (accessory pigments) – different patterns of light absorption, yellow, orange, brown pigments in flowers and fruits

4. Light absorption Visible spectrum of light light travels in waves (wavelength = distance between crests) light can be: transmitted, reflected, absorbed depends on pigment molecules ROY G BIV White – absorbs no light, reflects and transmits all light back to us Black – absorbs all light, does not reflect and transmit light back to us

5. Electron transport and capturing light energy to “make batteries” Photosystem (PS) cluster of pigment molecules (In thylakoid membrane) PSII and PSI pre-steps for capturing light accessory pigments absorb light, energy acquired and passed along energy reaches a specific pair of chlorophyll “a” molecules

Light Dependent Reactions Diagram

Step 1 light energy “excites” 2 chlorophyll a electrons in PS II (hey, get moving) electrons move to outer energy level

Step 2 2 electrons LEAVE chlorophyll a in PS II electrons move to a primary electron acceptor (PEA) PEA (located in thylakoid membrane) accepts electrons Oxidation reaction – reactant LOSES one or more electrons, becomes more positive in charge Reduction reaction – reactant GAINS one or more electrons, becomes more negative in charge

Step 3 2 electrons move along electron transport chain (ETC) energy LOST as electrons move along ETC energy used to pump protons (hydrogen ions) from the stroma INTO the thylakoid space proton pump (hydrogen ion pump) = active transport

Step 4 electrons PSI - electrons from chlorophyll a are “excited” (by photons of light) to another PEA PSII electrons reach PSI, replace the ones PSI lost

Step 5 PS I PEA donates electrons to a different ETC ETC brings electrons to stroma 2 electrons combine with H+ and NADP+ (electron acceptor) NADPH is made– (“battery” needed to make glucose) still need to make ATP “battery”

6. Restoring photosystems Problem: PS II missing 2 electrons enzyme in the thylakoid space splits water 2H2O  4H+ + 4e- + O2 H+ are left inside the thylakoid (used for ATP synthase) electrons go into PS II O2 “waste”

7. Chemiosmosis – MAKING ATP H+ ion gradient built using hydrogen ion pump Protons (H+ ions) PUMPED INTO thylakoid space HIGH protons inside thylakoid space ATP synthase ions DIFFUSE OUT of thylakoid through ATP synthase ATP synthase spins and makes ATP (adds phosphate group to ADP)  ATP “batteries” used to make glucose in stroma ATP synthase is a multifunctional protein

7. Chemiosmosis ATP synthase is a multifunctional protein

8. Carbon fixation incorporation of CO2 into organic compounds Calvin Cycle (C3 pathway, light independent reactions) occurs in STROMA of chloroplast most plants use this method ATP synthase is a multifunctional protein

Calvin Cycle (Light Independent Reactions) Diagram ATP synthase is a multifunctional protein

9. Calvin cycle (C3 pathway) light independent (no sun needed) carbon from CO2 “fixed” into organic compounds (carbon fixation) all steps occurs in the stroma (“goo”) of the chloroplast TWO “turns” of Calvin Cycle (3 CO2 molecules in at a time)  one glucose most plants are C3 plants (most plants use the Calvin cycle) ATP synthase is a multifunctional protein

Step 1 6CO2 enters the plant via stomata 6CO2 diffuses into the stroma of the chloroplast each C attaches to a 5-C compound (RuBP) using an enzyme (RuBisCO) 6-C molecules unstable  12 3-C molecules called PGA ATP synthase is a multifunctional protein

Step 2 12 PGA 12 G3P 12 ATP  12 ADP 12 NADPH  12 NADP+ creates 12 G3P (phosphate and H+ ion added to each PGA molecule, phosphate removed) recycle ADP, phosphate group, NADP+ for light reactions ATP synthase is a multifunctional protein

Step 3 6 C needed to produce one glucose 2 G3P leaves the Calvin Cycle  glucose 10 G3P converted back to 6 RuBP (each has 5 C) (ATP  ADP) allows Calvin Cycle to continue ATP synthase is a multifunctional protein

10. Alternative pathways of carbon fixation used in hot, dry climates stomata = holes through which plants “breathe” CO2 water loss through stomata hot climate = stomata closed prevents water loss makes CO2 unavailable ATP synthase is a multifunctional protein

11. C4 pathway (alternative pathway #1) sugarcane, corn, crabgrass stomata partially open during the day CO2 fixed into a 4-carbon compound lose half as much water as C3 plants, but produce the same amount of carbohydrate ATP synthase is a multifunctional protein

12. CAM pathway (alternative pathway #2) cactus, pineapple stomata only open at night CAM plants lose the least amount of water CO2 is fixed into other compounds that can be stored until the sun comes out very slow growers ATP synthase is a multifunctional protein

13. Rate of photosynthesis depends on these three major influences: light intensity CO2 availability temperature ATP synthase is a multifunctional protein

Light intensity As light intensity increases, the rate of photosynthesis initially increases. eventually reaches a plateau (maximum rate of photosynthesis) ATP synthase is a multifunctional protein

CO2 availability As CO2 availability increases, the rate of photosynthesis initially increases. will reach a plateau reactions can only occur so fast ATP synthase is a multifunctional protein

Temperature As temperature increases, the rate of photosynthesis increases up to a certain temperature. basically a tolerance curve too hot = stomata close, limits CO2 ATP synthase is a multifunctional protein

Chloroplast Diagram Use the image below to draw a chloroplast. Remember, the image below is of one granum (stack of thylakoids), so the outer membrane chloroplast should be close to the edge of the paper. Zoom in on the thylakoid membrane and draw and label the following structures: phospholipid bilayer, PSII, molecules that make up the electron transport chain, PS1, proton (H+ ion) pump, ATP synthase ATP synthase is a multifunctional protein

Light Dependent Reactions Diagram – Steps 1, 2, and 3 Summarize the events that take place during Steps 1, 2, and 3 of the light dependent reactions of photosynthesis. Paraphrase the details of each step in the space below. Draw arrows from these details to the correct location on the diagram.

Light Dependent Reactions Diagram – Steps 4 and 5 Summarize the events that take place during Steps 4 and 5 of the light dependent reactions of photosynthesis. Paraphrase the details of each step in the space below. Draw arrows from these details to the correct location on the diagram. Also paraphrase the process by which water is split by the enzyme in the thylakoid membrane.

Light Dependent Reactions Diagram Draw the process of light dependent reactions without looking at the diagram. The diagram you draw should be similar to the one we used in class.

Light Independent Reactions Steps – 1, 2, and 3 ATP synthase is a multifunctional protein

Light Independent Reactions Diagram Draw the process of light independent reactions without looking at the diagram. The diagram you draw should be similar to the one we used in class.

Light Dependent Reactions “Game Pieces” _____ + _____ + NADP+ (electron acceptor)  NADPH “battery” 2 e- H+ ADP + P (phosphate group) ATP “battery” 4 H+ H+ 2 e- 2 e- O2 H+ H+ H+ enzyme splits H2O to restore electrons in PSII and release oxygen 2H2O  _____ + _____ + _____ H+ H+

THYLAKOID MEMBRANE

THYLAKOID MEMBRANE

CALVIN CYCLE – LET’S FIX CARBON AND MAKE GLUCOSE! C-C-C-C-C RuBP C-C-C-C-C RuBP C-C-C-C-C RuBP C-C-C G3P C-C-C-C-C RuBP C-C-C-C-C RuBP C-C-C-C-C RuBP C-C-C G3P C-C-C G3P C-C-C G3P C-C-C G3P C-C-C G3P C-C-C G3P C-C-C G3P

12 NADPH  12 NADP+ (12 NADP+ reused in the light dependent reactions) C-C-C-C-C-C 6-carbon compound C-C-C-C-C-C 6-carbon compound 12 NADPH  12 NADP+ (12 NADP+ reused in the light dependent reactions) 12 ATP  12 ADP + 12 P (12 ADP and 12 phosphate groups are reused in the light dependent reactions) C-C-C-C-C-C 6-carbon compound C-C-C-C-C-C 6-carbon compound C-C-C-C-C-C 6-carbon compound C-C-C-C-C-C 6-carbon compound C-C-C G3P C-C-C G3P C-C-C G3P C-C-C G3P

10 G3P continue to make 6 molecules of RuBisCO (C-C-C-C-C) C-C-C PGA 2 G3P (C-C-C and C-C-C) leave to make glucose (C6H12O6) C-C-C PGA C-C-C PGA C-C-C PGA C-C-C PGA C-C-C PGA C-C-C PGA 6 ATP  6 ADP + 6 P (6 ATP needed to make 6 RuBP, 6 ATP and 6 P reused in light reactions C-C-C PGA C-C-C PGA C-C-C PGA

Draw the thylakoid membrane. Explain the light reactions to someone. phospholipid bilayer (0.5 points) primary electron acceptor (PEA) for photosystem I (0.5 points) photosystem II (make this the correct color) (0.5 points) primary electron acceptor (PEA) for photosystem II (0.5 points) photosystem I electron transport chain (ETC) (0.5 points) ATP synthase (0.5 points) photosystem II electron transport chain (ETC) (0.5 points) thylakoid space (label this location) (0.5 points) hydrogen ion (proton) pump (0.5 points) (0.5 points stroma (label this location) (0.5 points) photosystem I (make this the correct color) (0.5 points) label the hydrophobic and hydrophilic parts of the phospholipid bilayer (0.5 points)

Draw the Calvin Cycle. Explain it to someone. Start with 6 5-C molecules (RuBP) use 12 NADPH and 12 ATP when converting PGA  PGAL 6 CO2 enter the Calvin Cycle use 6 ATP when converting 10 PGAL  6 RuBP Make one glucose (C6H12O6)