Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
To Counteract the Greenhouse Effect: Plant a Tree Carbon Dioxide is one of the component gases of the “greenhouse” gas layer, which traps reradiated solar radiation near the surface of our planet and increases global warming. The more photosynthesis that takes place on our planet, the more carbon dioxide that is consumed in the photosynthetic process and the less carbon dioxide available to the greenhouse gas layer . PLANT A TREE TO COMBAT GLOBAL WARMING!!! To Counteract Ozone Holes: Plant a Tree • The ozone layer in the stratosphere is made up of oxygen. • It shields the planet against the damaging effects of ultraviolet radiation and other forms of solar radiation which increase global warming. • Holes in the ozone layer caused by anthropogenic pollution can be patched up with atmospheric oxygen. • Increasing photosynthetic output will increase atmospheric oxygen and help to repair the ozone layer. Photosynthesis and Cellular Respiration FOOD & ENERGY PRODUCTION Do We Need Plants? • Plants as carbon sinks, removing carbon dioxide from the atmosphere and oceans by fixing it into organic chemicals. • Plants also produce some carbon dioxide by their respiration, but quickly used by photosynthesis. • Plants also convert energy from light into chemical energy of C – C covalent bonds. • Animals are carbon dioxide producers that derive their energy from carbohydrates and other chemicals produced by plants by the process of photosynthesis. Overview of photosynthesis and respiration SUN RADIANT ENERGY PHOTOSYNTHESIS GLUCOSE RESPIRATION CELL ACTIVITIES ATP(ENERGY) Photosynthesis vs Respiration Photosynthesis and respiration as complementary processes in the living world. Photosynthesis uses the energy of sunlight to produce sugars and other organic molecules. These molecules in turn serve as food. Respiration is a process that uses O2 and forms CO2 from the same carbon atoms that had been taken up as CO2 and converted into sugars by photosynthesis. In respiration, organisms obtain the energy that they need to survive. Photosynthesis preceded respiration on the earth for probably billions of years before enough O2 was released to create an atmosphere rich in oxygen. (The earth's atmosphere presently contains 20% O2.) Plant – Soil Continuum Obtaining raw materials – sunlight • leaves = solar collectors – CO2 • stomates = gas exchange – H2O • uptake from roots – nutrients • uptake from roots In Plants Photosynthesis Occurs In the Chloroplasts Within the Leaves Leaves • Function of leaves – photosynthesis • energy production • CHO production – gas exchange – transpiration stoma simple vs. compound THE SUN: MAIN SOURCE OF ENERGY FOR LIFE ON EARTH Light Energy Harvested by Plants & Other Photosynthetic Autotrophs 6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2 Light Energy Harvested by Plants & Other Photosynthetic Autotrophs THE FOOD WEB Food Chain Producers: Produce Food • Photoautotrophs produce “food” which is consumed directly or indirectly by organisms at all trophic levels of a food chain/ web. WHY ARE PLANTS GREEN? It's not that easy being green Having to spend each day the color of the leaves When I think it could be nicer being red or yellow or gold Or something much more colorful like that… Kermit the Frog Electromagnetic Spectrum and Visible Light Gamma rays X-rays UV Infrared & Microwaves Visible light Wavelength (nm) Radio waves The Nature of Light Photons are discreet packets of light energy made in the sun that travel in waves of different lengths. Visible light is composed of wavelengths ranging from 380 to 750 nanometers. Photosynthetic pigments convert some of these visible light wavelengths into chemical energy. For Photosynthesis, light energy from the blue and red portions of the spectrum are converted to chemical bond energy. • Pigments absorb certain wavelengths of light and convert their energy into chemical energy. • Pigments reflect or transmit wavelengths of light energy that they do not convert to chemical energy, therefore, they appear this color. • Chlorophyll is green, therefore, it absorbs blue and red wavelengths of light Chloroplasts Have the Green Pigment Chlorophyll Chloroplast Pigments • Chloroplasts contain several pigments – Chlorophyll a – Chlorophyll b – Carotenoids The feathers of male cardinals are loaded with carotenoid pigments. These pigments absorb some wavelengths of light and reflect others. Sunlight minus absorbed wavelengths or colors equals the apparent color of an object. Why are plants green? Transmitted light WHY ARE PLANTS GREEN? Plant Cells have Green Chloroplasts The thylakoid membrane of the chloroplast is impregnated with photosynthetic pigments (i.e., chlorophylls, carotenoids). THE COLOR OF LIGHT SEEN IS THE COLOR NOT ABSORBED • Chloroplasts absorb light energy and convert it to chemical energy Light Reflected light Transmitted light Chloroplast Absorbed light Pigments • Visible color is from wavelengths not absorbed • Pigments capture light energy from absorbed wavelengths Photo = Light Synthesis = To Make • Light energy is converted to chemical bond energy. With this energy the chemical bonds of carbon dioxide and water are broken and reassembled into carbohydrates. In this process oxygen is also produced. PHOTOSYNTHESIS • Photosynthesis is the process by which autotrophic organisms use light energy to make sugar (glucose) and oxygen gas from carbon dioxide and water Carbon dioxide Water Glucose PHOTOSYNTHESIS Oxygen gas Six molecules of water + six molecules of carbon dioxide produce one molecule of sugar (glucose) + six molecules of oxygen THE BASICS OF PHOTOSYNTHESIS • Almost all plants are photosynthetic autotrophs, as are some bacteria and protists – Autotrophs generate their own organic matter through photosynthesis – Sunlight energy is transformed to energy stored in the form of chemical bonds (c) Euglena (a) Mosses, ferns, and flowering plants (b) Kelp (d) Cyanobacteria Photosynthesis • Method of converting sun energy into chemical energy usable by cells • Autotrophs: self feeders, organisms capable of making their own food – Photoautotrophs: use sun energy e.g. plants photosynthesis - makes organic compounds (glucose) from light – Chemoautotrophs: use chemical energy e.g. bacteria that use sulfide or methane chemosynthesis-makes organic compounds from chemical energy contained in sulfide or methane Photosynthesis • Photosynthesis takes place in specialized structures inside plant cells called chloroplasts – Light absorbing pigment molecules e.g. chlorophyll The location and structure of chloroplasts Chloroplast LEAF CROSS SECTION MESOPHYLL CELL LEAF Mesophyll CHLOROPLAST Intermembrane space Outer membrane Granum Grana Stroma Inner membrane Stroma Thylakoid Thylakoid compartment Photosynthesis occurs in chloroplasts • In most plants, photosynthesis occurs primarily in the leaves, in the chloroplasts • The leaves have the most chloroplasts • The green color comes from chlorophyll in the chloroplasts • The pigments absorb light energy • A chloroplast contains: – stroma, a fluid – grana, stacks of thylakoids • The thylakoids contain chlorophyll – Chlorophyll is the green pigment that captures light for photosynthesis Chloroplast two outer membranes thylakoid membrane system Organelle of photosynthesis in plants and algae stroma thylakoid compartment Location of Photosynthetic Reactions • The two chemical reactions of photosynthesis are localized: 1. The conversion of sunlight energy to chemical energy (light-dependent reactions) occurs on the thylakoid membranes 2. The synthesis of glucose and other molecules (light-independent reactions) occurs in the surrounding stroma Two Groups of Reactions 1. Light-dependent reactions – Chlorophyll and other molecules of the thylakoids capture sunlight energy – Sunlight energy is converted to the energy carrier molecules ATP and NADPH – Oxygen gas is released as a by-product Two Groups of Reactions 2. Light-independent reactions – Enzymes in the stroma synthesize glucose and other organic molecules using the chemical energy stored in ATP and NADPH Light-dependent Reactions • Photosystem: light capturing unit, contains chlorophyll, the light capturing pigment • Electron transport system: sequence of electron carrier molecules that shuttle electrons, energy released to make ATP • Electrons in chlorophyll must be replaced so that cycle may continue - these electrons come from water molecules, oxygen is liberated from the light reactions • Light reactions yield ATP and NADPH used to fuel the reactions of the Calvin cycle (light independent or dark reactions) How the Light Reactions Generate ATP and NADPH Primary electron acceptor Primary electron acceptor Energy to make NADP 3 2 Light Light Primary electron acceptor 1 Reactioncenter chlorophyll Water-splitting photosystem 2 H + 1/2 NADPH-producing photosystem Calvin Cycle (light independent or “dark” reactions) • ATP and NADPH generated in light reactions used to fuel the reactions which take CO2 and break it apart, then reassemble the carbons into glucose. • Called carbon fixation: taking carbon from an inorganic molecule (atmospheric CO2) and making an organic molecule out of it (glucose) • Simplified version of how carbon and energy enter the food chain PHOTOSYNTHESIS • The light reactions convert solar energy to chemical energy Light Chloroplast NADP – Produce ATP & NADPH • The Calvin cycle makes sugar from carbon dioxide – ATP generated by the light reactions provides the energy for sugar synthesis – The NADPH produced by the light reactions provides the electrons for the reduction of carbon dioxide to glucose ADP +P Light reactions Calvin cycle Review: Photosynthesis uses light energy to make food molecules A Summary of the Chemical Processes of Photosynthesis Chloroplast Light Photosystem II Electron transport chains Photosystem I CALVIN CYCLE Stroma Cellular respiration Cellulose Starch LIGHT REACTIONS CALVIN CYCLE Other organic compounds The Importance of Photosynthesis • The energy entering chloroplasts as sunlight gets stored as chemical energy in organic compounds • Sugar made in the chloroplasts supplies chemical energy & carbon skeletons to synthesize the organic molecules of cells • Plants store excess sugar as starch in structures such as roots, tubers, seeds, & fruits • In addition to food production, photosynthesis produces the O2 in our atmosphere Summary • Light Dependent Reaction – Light + chlorophyll --> ATP + NADPH + (O2 as waste) • Light Independent Reaction (Calvin Cycle) – CO2 + ATP + NADPH --> glucose Starch What happens to the glucose produced by photosynthesis? CH2OH O H H O CH2OH H OH H H OH Glucose subunit O H H O CH2OH H OH H H OH Glucose subunit O H H O H OH H H OH Glucose subunit O Up to 1000 or more monomers What happens to the glucose produced by photosynthesis? Sucrose CH2OH O H O HOCH2 H H H OH H O H HO CH2OH HO H OH Glucose subunit HO H Fructose subunit It's not that easy being green… but it is essential for life on earth!