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Parker Cade

on 7 January 2013

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Transcript of Photosynthesis

Linear Electron Flow. Photosynthesis Equation 6 CO2 + 6 H2O + Light Energy Reactants Carbon dioxide gets into the leaf from the stomata and water gets into the plant through its roots. The light energy comes from the sun. Products The products from the equation are glucose and oxygen. The glucose is converted into starch and is then temporarily stored.
The oxygen is released into the air. C6H12O6 + 6 O2 Oxidized Reduced The photosynthesis equation is a chemical representation of the process of photosynthesis which takes place in the chloroplasts.
Plants take in carbon dioxide and water to produce glucose (a sugar) and oxygen. 6 CO2 + 6H2O + Light Energy C6H12O6 + 6 O2 This equation is formed from two separate processes. Light Reaction Calvin Cycle Light Reaction This reaction requires the direct energy of light to produce energy carrier molecules used for the second process.
Converting solar energy to chemical energy The chloroplast absorbs photons and water Violet-blue and red light work best for photosynthesis, those being the most absorbed (Isolated)
Electron is raised to excited state. Gives off heat and fluorescence when returning to ground state. (Intact)
Absorbed by pigment molecule Reaches reaction-center complex (Photosystem). Light-harvesting complex Photosystem I and II Made of a primary electron acceptor along with specific proteins. Reaction center complex in I is called P700 and in II it is called P680 Found in the Thylakoid membrane Photon strikes pigment molecule in a light-harvesting complex, the energy is passed until it reaches the P700 or P680. The excited electron from the special pair of chlorophyll a molecules is transferred to the primary electron acceptor. Producing ATP and NADPH
Excited electrons are passed down the second electron transport chain through ferredoxin.
NADP+ reductase catalyzes the transfer of electrons from Fd to NADP+. Two electrons are required for the reduction to NADPH, thus forming NADPH. Enzyme splits water molecule into two electrons, two hydrogen ions and an oxygen. The electrons replace transferred elections in the primary election acceptor, the hydrogen are released into the thylakoid lumen and, the oxygen immediately combines with an oxygen atom, forming O2. Excited electrons pass from the primary electron acceptor to the PS I from the electron transport chain.
The electrons moving to a lower energy level provides the energy for ATP synthesis.
Light energy is transferred from light-harvsting complex pigments to the P700 of PS I. Excited electrons are transferred to the primary electron acceptor, creating an electron hole, resulting in P700+. ATP and NADPH Produces Photosynthesis Photosynthesis is the process in which chloroplasts of autotrophs capture light energy from the sun and convert it into chemical energy that is stored in sugar and other organic molecules. All heterotrophs depend on this process because they in turn consume the plants and receive the energy. Chloroplasts Chloroplasts are the sites where photosynthesis takes place. There are about half a million chloroplasts in a chunk of leaf with a top surface area of 1 mm^2 Chloroplasts are found in the tissue in the interior of the leaf called the mesophyll. Endosymbiotic theory The Endosymbiotic theory says that chloroplasts were once free living bacterium. Chloroplasts are the result of years of evolution initiated by endocytosis of bacteria. Chlorophyll is the substance that allows the chloroplasts to capture sunlight, and they are found in thylakoids. Leaf Structure Upper
Epidermis Cuticle Palisade Mesophylls Spongy Mesophylls Guard
Cells Stoma Cuticle Lower Epidermis Phloem Xylem The Calvin Cycle The Calvin Cycle is anabolic and builds carbohydrates from smaller molecules and consumes energy. Carbon enters the Calvin Cycle in the form of CO2 and leaves in the form of sugar. The cycle uses ATP as an energy source and consumes NADPH as reducing power for adding high energy electrons to make sugar. Electromagnetic spectrum -thin layer of waxy substances covering over the outer surfaces of the epidermis
-protects against water loss / water gain and is generally thicker on plants that live in dry environments
-protects from damage, bacteria, insects, and fungi
-secreted by the epidermis
-often thinner on the underside of leaves. The visible light is the radiation that drives photosynthesis Chloroplast Pigments absorb this light at different wavelengths Mitochondria Participates directly in light reactions Absorption Spectrum chemiosmosis
ATP synthase complex
intermembrane space
intermembrane fluid Accessory pigment Photoprotection oxidative phosphorylation
food energy
two layered membrane photophosphorylation
three layered membrane closely and neatly packed cylinder shaped cells
tight packing ensures maximum light capture
close to the walls of the cell, for optimal advantage of the light source.
contain most of the leaf's chlorophyll -share the same basic mechanism of generating ATP -similar iron containing electron carriers -similar mechanical structure and function Photorespiration ~C3 Plants ~C4 Plants ~CAM Plants Photo/respiration "Photo"- light "Respiration"-producing CO2 Differences of photorespiration. Photorespiration- Unlike normal respiration, photorespiration does not generate ATP, instead, ATP is consumed. Unlike photosynthesis, Photorespiration does not produce sugar. Photorespiration decreases photosynthetic output by siphoning organic material from the Calvin cycle and releasing CO2 that would otherwise be fixed. C3 Plants. C3 Plants Plants that initial fixation of Carbon occurs in. They are called C3 plants because the first organic product of Carbon fixation is a three-Carbon compound. Ex: Rice, wheat and soy beans. Photorespiration for C3 plants. On hot, dry days, C3 plants produce less sugar which is due to less CO2 being produced. Rubisco can bind O2 in place of CO2 and adds it to the Calvin cycle. The product splits and a two-carbon compound leaves the Chloroplast. Peroxisomes and Mitochondria rearrange and split which releases CO2. C4 Plants Named so because they preface the Calvin cycle with an alternate mode of carbon fixation that forms a four-carbon compound as its first product. Ex: Sugarcane, corn, and members of the grass family. Photosynthetic Cells (Two types) Bundle-Sheath cells- Bundle-sheath cells are tightly packed sheaths around the veins of the leaf. Mesophyll Between the bundle sheath and the leaf surface are the more loosely arranged mesophyll cells. CAM Plants CAM-Crassulaccean acid metabolism CAM Plants have a second photosynthetic adaptation to arid conditions. They are succulent plants that have the ability to store water. Ex: Cacti, and pineapples. CAM Plants (cont.) CAM plants open their stomata During the night and close them during the day. Closing Stoma during the day helps desert plants conserve water, and prevents CO2 from entering the leaves.
During the night, when their stomata are open, these plants take up CO2 and incorporate it into a variety of organic acids.
This mode of carbon fixation is the CAM, or Crassulacean acid metabolism.
The mesophyll cells in CAM plants store organic acids in their vacuoles until morning.
During the day, the light reactions supply ATP and NADPH for the Calvin cycle, CO2 is released from the organic acids to become sugar in the chloroplasts. C3, C4, and CAM differences
and similarities C3, C4 and CAM plants all exist in hot and dry climates. C4 and CAM Plants are both charastorized by preliminary incorporation of CO2 into organic acids, followed by the transfer of CO2 to the Calvin cycle The C4 and CAM pathways are two evolutionary solutions to the problem of maintaining photosynthesis with stomata partially or completely closed on hot, dry days single layer of cells containing few or no chloroplasts
quite transparent and permit most of the light that strikes them to pass through to the underlying cells
only a few stomata on the uppermost layer and produces the waxy substance that becomes part of the cuticle. type of vascular tissue that provides structural support.
made of dead cells
primarily involved in transporting water, nutrient and dissolved minerals from the roots to all the other parts of the plant -oxidizes organic molecules to obtain electrons -source of electrons is water -transforms light energy into chemical energy in ATP -transfer chemical energy from food to ATP living tissue in a vascular plant that functions primarily in transporting organic food materials (e.g. sucrose) from the photosynthetic organ (leaf) to all the parts of the plant. -vast network of interconnected membranous sacs located within the stroma This is a single layer of cells containing few or no chloroplasts. The cells are quite transparent . There are more stomata on the lower layer than the upper epidermis. The distance between the crests of electromagnetic waves. -both function as H+ resevoirs Vein -the spongy colorless matrix of the cell that functionally supports the cell -the mitochondrial matrix and the stroma serve the same purpose Veins provide support for the leaf and transport both water and minerals ,via xylem, and food energy ,via phloem, through the leaf and on to the rest of the plant. Cylic Electron Flow -consists of three phospholipid bilayers -consists of two phospholipid bilayers Vascular Tissue Plant circulatory center; helps in the transportation of water,minerals and manufactured food. Ground Tissue function in photosynthesis, storage, and transport
make up the majorityof plant structure
composed of three cell types: parenchyma, collenchyma, and sclerenchyma cells. Dermal Tissue outer protective covering of plants. -oxidizes water to obtain electrons -source of ATP -double phospholipid bilayer -triple phospholipid bilayer -both use electron carrying iron containing proteins -function as H+ resevoirs irregularly shaped, loosely packed cells
contain some chlorophyll
functions mainly in gas exchange
loose packing allows for maximized gas exchange
communicate with gaurd cells and regulate stoma by monitering gas levels occur in pairs
flank each stoma
regulate stoma by turgor pressure
keeps optimal amounts of gas and moisture within the leaf tiny pore in the leaf
surrounded by guard cells that regulate its opening and closure
serves as site for gas exhange
exclusive to the bottom of the leaf to avoid excess transpiration P.2 Austin Wood, Jessie Crothers, Matt Hentz, and Parker Cade
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