PHOTOSYNTHESIS

2 Photosynthesis _______ (small molecules combined)_______ (small molecules combined) _______ (stores energy)_______ (stores energy) ___________ (CO 2 ) requiring process that uses ________ (photons) and _____ (H 2 O) to produce _______ ____________ (glucose).___________ (CO 2 ) requiring process that uses ________ (photons) and _____ (H 2 O) to produce _______ ____________ (glucose). 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 glucose SUN photons

3 Question: Where does photosynthesis take place?

4 Plants ________ – produce their own food (glucose)________ – produce their own food (glucose) Process called ___________Process called ___________ Mainly occurs in the leaves:Mainly occurs in the leaves: a._____ - pores b._______ cells Stoma Mesophyll Cell Chloroplast

5 Stomata (stoma) ____ in a plant’s cuticle through which _______ and ____ (CO 2 & O 2 ) are exchanged between the plant and the atmosphere. Guard Cell Carbon Dioxide (CO 2 ) Oxygen (O 2 ) Found on the ______ of leaves Stoma

6 Mesophyll Cell of Leaf Cell Wall Nucleus Chloroplast Central Vacuole ___________ occurs in these cells!

7 Chloroplast _______photosynthesis _______ where photosynthesis takes place. Granum Thylakoid Stroma Outer Membrane Inner Membrane Thylakoid stacks are connected together

8 Thylakoid Thylakoid Membrane Thylakoid Space Granum Grana make up the ____________

9 Question: Why are plants green?

10 Chlorophyll Molecules Located in the thylakoid membranesLocated in the thylakoid membranes Chlorophyll have ___ in the centerChlorophyll have ___ in the center Chlorophyll pigments harvest ______ (photons) by absorbing certain wavelengths (___-420 nm and ___- 660 nm are most important)Chlorophyll pigments harvest ______ (photons) by absorbing certain wavelengths (___-420 nm and ___- 660 nm are most important) Plants are green because the green wavelength is _______, not absorbedPlants are green because the green wavelength is _______, not absorbed.

11

12 Wavelength of Light (nm) Short waveLong wave (more energy)(less energy)

13 Absorption of Light by Chlorophyll wavelength Absorption violet blue green yellow orange red Chlorophyll absorbs blue-violet & red light best

14 Question: During the fall, what causes the leaves to change colors?

15 Fall Colors In addition to the chlorophyll pigments, there are other pigments presentIn addition to the chlorophyll pigments, there are other pigments present During the fall, the green chlorophyll pigments are greatly reduced revealing the other pigmentsDuring the fall, the green chlorophyll pigments are greatly reduced revealing the other pigments _________ are pigments that are either red, orange, or yellow_________ are pigments that are either red, orange, or yellow

16 Redox Reaction The transfer of one or more electrons from one reactant to another Two types: 1._______ is the loss of e - 2._______ is the gain of e -

17 Oxidation Reaction The loss of electrons from a substance or the gain of oxygen. glucose 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 Oxidation Carbon dioxide Water Oxygen

18 Reduction Reaction The gain of electrons to a substance or the loss of oxygen. glucose 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 Reduction

19 Question: What do cells use for energy?

20 Energy for Life on Earth ______ is the ULTIMATE energy for all life on Earth Plants store energy in the _______ _____ of sugars Chemical energy is released as ___ during cellular respiration

21 Structure of ATP ___ stands for adenosine triphosphate It is composed of the nitrogen base ______, the pentose (5C) sugar ______, and three PHOSPHATE groups The ____ phosphate group is bonded with a HIGH ENERGY chemical bond This bond can be BROKEN to release ENERGY for CELLS to use

22 Removing a Phosphate from ATP Breaking the LAST PHOSPHATE bond from ATP, will --- –Release ______ for cells to use –Form ___ –Produce a FREE PHOSPHATE GROUP

23 High Energy Phosphate Bond

24 FREE PHOSPHATE can be re-attached to ADP reforming ATP Process called ___________

25 Phosphorylation

26 Parts of Photosynthesis

27 Two Parts of Photosynthesis Two reactions make up photosynthesis: 1._____ Reaction or ____ _________ Reaction - Produces energy from solar power (photons) in the form of ATP and NADPH. SUN

28 Two Parts of Photosynthesis 2. ________ or ____ __________ Reaction Also called _________ or C 3 FixationAlso called _________ or C 3 Fixation Uses energy (ATP and NADPH) from light reaction to make sugar (glucose).Uses energy (ATP and NADPH) from light reaction to make sugar (glucose).

29 Light Reaction (Electron Flow) Occurs in the ________ _________Occurs in the ________ _________ During the light reaction, there are two possible routes for electron flow:During the light reaction, there are two possible routes for electron flow: A.___________ Flow B.___________ Flow

30 Cyclic Electron Flow Occurs in the thylakoid membrane.Occurs in the thylakoid membrane. Uses ______________Uses ______________ P700 reaction center- chlorophyll aP700 reaction center- chlorophyll a Uses Electron Transport Chain (ETC)Uses Electron Transport Chain (ETC) Generates ______Generates ______ ADP + ATP P

31 Cyclic Electron Flow P700 Primary Electron Acceptor e-e- e-e- e-e- e-e- ATP produced by ETC Photosystem I Accessory Pigments SUN Photons Pigments absorb light energy & excite e- of Chlorophyll a to produce ATP

32 Noncyclic Electron Flow Occurs in the thylakoid membraneOccurs in the thylakoid membrane Uses __________ and ____________Uses __________ and ____________ P680 reaction center (PSII) - chlorophyll aP680 reaction center (PSII) - chlorophyll a P700 reaction center (PS I) - chlorophyll aP700 reaction center (PS I) - chlorophyll a Uses Electron Transport Chain (ETC)Uses Electron Transport Chain (ETC) Generates ______________Generates ______________

33 Noncyclic Electron Flow P700 Photosystem I P680 Photosystem II Primary Electron Acceptor Primary Electron Acceptor ETC Enzyme Reaction H 2 O 1/2O 2 1/2O 2 + 2H + ATP NADPH Photon 2e - SUN Photon H 2 O is split in PSII & ATP is made, while the energy carrier NADPH is made in PSI

34 Noncyclic Electron Flow ADP +  ATPADP +  ATP NADP + + H  NADPHNADP + + H  NADPH Oxygen comes from the splitting of H 2 O, not CO 2Oxygen comes from the splitting of H 2 O, not CO 2 H 2 O  1/2 O 2 + 2H + H 2 O  1/2 O 2 + 2H + P

35 Chemiosmosis Powers ATP synthesisPowers ATP synthesis Takes place across the thylakoid membraneTakes place across the thylakoid membrane Uses ETC and ATP synthase (enzyme)Uses ETC and ATP synthase (enzyme) H+ move down their concentration gradient through channels of ATP synthase forming ATP from ADPH+ move down their concentration gradient through channels of ATP synthase forming ATP from ADP

36 Calvin Cycle Carbon Fixation (light independent reaction)Carbon Fixation (light independent reaction) C 3 plants (80% of plants on earth)C 3 plants (80% of plants on earth) Occurs in the ______ Occurs in the ______ Uses _________ from light reaction as energyUses _________ from light reaction as energy Uses CO 2Uses CO 2 To produce glucose: it takes 6 turns and uses 18 ATP and 12 NADPH.To produce glucose: it takes 6 turns and uses 18 ATP and 12 NADPH.

37 Chloroplast Granum Thylakoid STROMA– where Calvin Cycle occurs Outer Membrane Inner Membrane

38 Calvin Cycle Remember: C 3 = Calvin Cycle C3C3 Glucose

39 C 4 Plants Hot, moist environmentsHot, moist environments 15% of plants (grasses, corn, sugarcane)15% of plants (grasses, corn, sugarcane) Photosynthesis occurs in 2 placesPhotosynthesis occurs in 2 places Light reaction - mesophyll cellsLight reaction - mesophyll cells Calvin cycle - bundle sheath cellsCalvin cycle - bundle sheath cells

40 CAM Plants Hot, dry environmentsHot, dry environments 5% of plants (cactus and ice plants)5% of plants (cactus and ice plants) Stomates closed during dayStomates closed during day Stomates open during the nightStomates open during the night Light reaction - occurs during the dayLight reaction - occurs during the day Calvin Cycle - occurs when CO 2 is presentCalvin Cycle - occurs when CO 2 is present

41 Question: Why do CAM plants close their stomata during the day?

Cam plants close their stomata in the hottest part of the day to conserve water