PHOTOSYNTHESIS

Victoria Johnson

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What is photosynthesis?

• The process by which plants and some bacteria use the energy from sunlight to produce sugar, which then cellular respiration converts into ATP, the "fuel" used by all living things.

• 6H2O + 6CO2 ----------> C6H12O6+ 6O2

• The conversion of unusable sunlight energy into usable chemical energy, is associated with the actions of the green pigment chlorophyll. Most of the time, the photosynthetic process uses water and releases the oxygen that we absolutely must have to stay alive. (Wiley&).

Leaves and their structure:

• The raw materials of photosynthesis, water and carbon dioxide, enter the cells of the leaf, and the products of photosynthesis, sugar and oxygen, leave the leaf.(PhotoBritannica)

• important to the study of photosynthesis: stoma, guard cell, mesophyllcells, and vein. google.images.com

• Water enters the root and is transported up to the leaves through specialized plant cells known as xylem. Land plants must guard against drying out and so have evolved specialized structures known as stomata to allow gas to enter and leave the leaf. Carbon dioxide cannot pass through the protective waxy layer covering the leaf (cuticle), but it can enter the leaf through an opening flanked by two guard cells. Which is something we have all seen many times in biology lab. Likewise, oxygen produced during photosynthesis can only pass out of the leaf through the opened stomata (Photo columbia).

C02 enters through the guard cells

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Chlorophyll:

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• A pigment is any substance that absorbs light. The color of the pigment comes from the wavelengths of light reflected (in other words, the ones not absorbed) (Cronquist, Arthur).

• Black pigments absorb all of the wavelengths that strike them. White pigments/lighter colors reflect all or almost all of the energy striking them, (Cronquist, Arthur).

• Chlorophyll, the green pigment common to all photosynthetic cells, absorbs all wavelengths of light except green, which is why it reflects green in our eyes, (Cronquist, Arthur).

Other pigments

• Chlorophyll is a complex molecule.

• All photosynthetic organisms contain chlorophyll a.

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• Accessory pigments include chlorophyll b(c, d, and e in algae and protistans), xanthophylls, and carotenoids(such as beta-carotene).

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(Bonner, James)

Stages of photosynthesis:

• Photosynthesis is a two stage process.

• The Light Reactions occur in the grana and the Dark Reactions take place in the stroma of the chloroplasts, (Gasexchange).

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Light reaction:

• light strikes chlorophyll a in such a way as to excite electrons to a higher energy state. In a series of reactions the energy is converted into ATP and NADPH. Water is split in the process, releasing oxygen as a by-product of the reaction. The ATP and NADPH are used to make C-C bonds in the other process, dark reaction, (Bonner, James).

• The first process is the Light Dependent Process (light reaction), requires the direct energy of light to make energy carrier molecules that are used in the second process, (Bonner, James).

Dark reaction

• Dark reactions occurs when the products of the Light Reaction are used to form C-C covalent bonds of carbohydrates. The Dark Reactions can usually occur in the dark, if the energy carriers from the light process are present.

How does any of this happen?

• “This occurs when the electrons from water are excited by the light in the presence of P680, (Gasexchange).

• “ Light energy causes the removal of an electron from a molecule of P680. The P680 requires an electron, which is taken from a water molecule, breaking the water into H+ ions and O-2 ions. These O-2 ions combine to form the diatomic O2

that is released” (Solarenergy).

• The electron is then "boosted" to a higher energy state and attached to a primary electron acceptor, which begins a series of redox reactions, passing the electron through a series of electron carriers

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• The electron is then passed again through a series of redox reactions, eventually being attached to NADP+ and H+ to form NADPH, an energy carrier needed in the dark reaction.

• The electron from Photosystem II replaces the excited electron in the P700 molecule. There is thus a continuous flow of electrons from water to NADPH… This energy is used in Carbon Fixation.

(Solarenergy)

summary

• Sunlight

• Produce sugar

• Two stage process-dependency

• Sugar converts to ATP

• ATP= “fuel” for all living things

• Sunlight turned into chemical energy

• chlorophyll

Benefits: Plants

• Photosynthesis is the process by which plants use energy from the sun (along with carbon dioxide and water) to create its own food. Without photosynthesis, plants would die.

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• “Photosynthesis is responsible for the conversion of carbon from carbon dioxide into organic compounds in plants. It allows the plant to make organic building blocks, new cells, starch, and proteins. Without this process, life as we know it would not exist on earth. Plants provide, directly or indirectly, food for all animals and all of our atmospheric oxygen” (San Luis).

Benefits: Earth and its people

• Photosynthesis is the process by which plants make their own food. Plants use sunlight and light energy to make their own food in order to survive; without photosynthesis, there would be no plants, and without plants there would be no oxygen and therefore the world could not survive either.

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WORK CITED

• Wiley and Sons, Inc, John. "Interactive Concepts in Biochemistry - Photosynthesis." Wiley: Home. 2002. Web. 04 Oct. 2011. <http://www.wiley.com/legacy/college/boyer/0470003790/animations/animations.htm>.

• "Photosynthesis." The Columbia Encyclopedia. New York: Columbia UP, 2008. Credo Reference. 7 Nov. 2008. Web. 7 Oct. 2011. <http://www.credoreference.com/entry/columency/photosynthesis>.

• "Photosynthesis." Dictionary of Microbiology & Molecular Biology. Hoboken: Wiley, 2006. Credo Reference. 18 Mar. 2010. Web. 7 Oct. 2011. <http://www.credoreference.com/entry/wileymicrob/photosynthesis>.

• "Photosynthesis." Britannica Concise Encyclopedia. Chicago: Encyclopaedia Britannica, 2009. Credo Reference. 3 Sept. 2010. Web. 7 Oct. 2011. <http://www.credoreference.com/entry/ebconcise/photosynthesis>.

• "Gas Exchange." The Hutchinson Unabridged Encyclopedia with Atlas and Weather Guide. Abington: Helicon, 2010. Credo Reference. 4 Jan. 2011. Web. 7 Oct. 2011. <http://www.credoreference.com/entry/heliconhe/gas_exchange>.

• Bonner, James. "Chlorophyll." Encyclopedia Americana. Grolier Online, 2011. Web. 7 Oct. 2011.• Cronquist, Arthur. "Leaf." Encyclopedia Americana. Grolier Online, 2011. Web. 7 Oct. 2011.• Bassham, James A. "Calvin, Melvin (1911–1997)." Encyclopedia Americana. Grolier Online, 2011.

Web. 7 Oct. 2011.• "Solar Energy." Encyclopedia Americana. Grolier Online, 2011. Web. 7 Oct. 2011.• Sinnott, Edmund W. "Botany." Encyclopedia Americana. Grolier Online, 2011. Web. 7 Oct. 2011.

Pictures..

• 123RF.com

• Betty’s original embroideries

• Thecockeyedregister.com

• google.images.com

• SanLuisObispo

• wikipedia