Photosynthesis

=Chapter 10: Photosynthesis=

by Alicia Garcia = =

Related activities

 * Lab 4
 * Ch 10: Photosynthesis worksheets
 * Ch 10: Photosynthesis Part 2, Worksheet
 * Note taking in class
 * [|BioCoach Activity]

Vocabulary

 * [|ATP]
 * [|Bundle-sheath cells]
 * [|C4 Plants]
 * [|Calvin Cycle]
 * __[|Carbon fixation]__
 * [|Carotenoids]
 * [|CAM/Crassulacean acid metabolism]
 * [|Chlorophyll a]
 * [|Chlorophyll b]
 * [|Cyclic electron flow]
 * [|Cyclic photophosphorylation]
 * [|Glyceraldehyde 3-phosphate]
 * [|Light reactions]
 * [|Mesophyll]
 * [|Mesophyll Cells]
 * [|Noncyclic electron flow]
 * [|Noncyclic photophosphorylation]
 * [|NADP÷]
 * [|PEP carboxylase]
 * [|Photophosphorylation]
 * [|Photosystems]
 * [|Photosystem I and Photosystem II]
 * [|Primary electron acceptor]
 * [|Reaction center]
 * [|Rubisco]
 * [|Stomata,stoma]
 * [|Visible light]




 * Objective 2a**
 * The major site for photosynthesis in most plants are the leaves
 * What makes the color have leafs is the pigment chlorophyll, which is found in the mesophyll
 * CO2 enters the leaf and H2O exits through the stomata


 * Objective 1**
 * The Chemical equation of photosynthesis: 6CO2 + 12H2O + light energy = C6H12O6 + 6O2 + 6H2O
 * Objective 2**
 * Two stages of photosynthesis: Light reactions and the Calvin Cycle
 * Light reactions convert solar energy to chemical energy, which generates NADPH and ATP
 * Carbon fixation starts the Calvin Cycle. Makes Sugar with the help of the ATP and NADPH
 * occurs during the day light
 * occurs in the stroma
 * The thylakoids of the chloroplast is the site of the light reactions.
 * NADH+ and ADP crashes into the thylakoid membrane, picking up electrons and phosphate


 * Objective 3**
 * Light is a form of electromagnetic energy, can also be called radiation
 * Pigments are substances that absorb visible light
 * the leaf of a plant is green due to chlorophyll absorbs the red and blue light while reflecting green light [[image:http://ecosys.cfl.scf.rncan.gc.ca/images/sch_chloro_e.gif align="right"]]
 * Chlorophyll a is a major pigment that can participate directly in light reactions.located in the thylakoid membrane; other pigments absorb light and transfer the energy to chlorophyll a, then it initiates the light reactions; these pigments are called chlorophyll b and cartenoids
 * Photosystems are the light-harvesting units of the thylakoid membrane
 * Has a light gathering "antenna complex" consisting of a cluster of a few hundred chlorophyll a, chlorophyll b, abd carotenoid molecules
 * In the reaction center consist of chlorophylla and oxidation reaction
 * When energy drives an oxidation- reduction reaction, an excited electron from the reaction- center chlorophyll is captured by electron acceptor before it can return to the ground state.
 * Two types of photosystems: Photosystem I and photosystem II
 * PSI (p700)
 * pigment is best at absorbing light having a wavelength of 700nm (far red part of spectrum)
 * PSII(P68)
 * Absorption spectrum has a peak at 680nm
 * How noncyclic eletron flow during the light reaction. (It generates ATP and NADPH)
 * 1. Light reactions absorbs PSII, an electron in the region of PSII becomes excited and is captured by the primary electron acceptor
 * 2. An enzyme takes electrons from water and gives them to PSII, which replaces the electrons that the chlorophyll molecule lost when it absorbed light energy. As this is taking place it forms O2
 * 3. Electrons passes from the primary electron acceptor of PSII to PSI through an electron transport chain (ETC)
 * The ETC has proteins which the electrons go throught: Plastoquinone (pq) Cytochromes and plastocyanin (pc)
 * 4. At a lower energy ATP is produced. ATP will provide chemical energy for the synthesis of sugar during the calvin cycle. This is the 2nd major stage of photosynthesis.
 * 5. When the electron reaches the end of the ETC, it will fill a "hole" of PSI. The "hole" happened was due to when the light energy drove an electron of PSI to the primary acceptor of PSI.
 * 6. Electrons move through another ETC then goes through another protien called ferredoxin (fd) than to NADP+ reductase and stores the energy in NADPH.
 * Cyclic electron flow
 * Short circuit
 * Uses PSI not PSII
 * electrons travel from PSI to (fd), then to the cytochrome back to reaction center.


 * Objective 4**
 * Its easier to understand the Calvin Cycle in 3 phases
 * 1. Carbon fixation
 * Each CO2 molecule binds to a 5-C sugar named ribulose bisphospahte (RuBP), making a 6-C. This phase is catalyzed by RuBP carboxylase/Rubisco.
 * 2. Reduction:
 * The plant cell uses the one molecule that exited the cycle, as for the other five molecules they are recycled to regenerate the three molecules of RuBP
 * 3. Regeneration
 * In the last step G3P are rearranged into three molecules of RuBP and the cycle begins again


 * Objective 5**
 * C3 plants:
 * examples of these plants: Rice, wheat, and soybeans.
 * These plants produce less foods, on hot and dry days; their stomates close
 * since no CO2 is able to get it in; the plants has low levels of what is left of CO2
 * O2 replaces CO2 by Rubisco
 * This is photorespiration it does no generate ATP or food.
 * C4 Plants:
 * ex's: sugar canes, corn, or members of the grass family.
 * Produces 4-C compound.
 * CO2 is fixe4d by phosphoenolpyruvate (PEP) to form 4-C oxaloacetate


 * CAM Plants:
 * Ex's: Water-storing plants, cacti, pineapple, (desert plants)
 * Conserves water and prevents CO2 to enter.
 * Open stomata during the night and closes them in the day.


 * »»They all use calvin cycle to make sugar from CO2»»**