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Energy • Ability to do work, moves or changes matter. • Comes in many different forms (chemical energy, potential energy, solar energy, electricity, heat). • Never created or destroyed only transformed. Autotrophs - Organisms which make their own food, directly utilize the sun’s energy (i.e trees). Heterotrophs - Organisms who obtain energy from the food they consume, cannot directly utilize the sun’s energy (i.e. bears) ATP - Adenosine Triphosphate • Cells’ energy molecule. Energy is stored within the bonds of the phosphates. • ATP is used to run all cellular activity (protein synthesis, membrane pumps, DNA regulation). • ADP (2P) would be a dead battery while ATP (3P) would be a charged battery. Photosynthesis: Using light to make food The gift of a green world. • Life on Earth is solar powered. • By converting the energy in sunlight into chemical energy, photosynthesis produces 160 billion metric tons of carbohydrates each year. Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings THE BASICS OF PHOTOSYNTHESIS • Almost all plants are photosynthetic autotrophs, as are some bacteria and protists. – They generate their own organic matter through photosynthesis. (c) Euglena (d) Cyanobacteria (b) Kelp (a) Mosses, ferns, and flowering plants Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Figure 7.2 Kingdom Plantae Simple Plants: (a) Mosses Simple Plants: (a) Mosses, (b) Hornworts, (c) Liverworts Ferns Cone Trees Flowering Plants • With flowers for reproduction • Seeds are produced inside the fruit (matured ovary) Water Lily Leaf Victoria regia Succulent cacti Cacti Carnivorous plants obtain some of their nutrients from animal tissues. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Photosynthesis • Plant process whereby the energy in the sun is used to convert H2O and CO2 into high energy sugars and O2 waste. • 6CO2 + 6H2O + sun energy C6H12O6 + 6O2 Light • Sun: white light (energy) is composed of a range of wavelengths (colors) Gamma rays X-rays UV Infrared Visible light Wavelength (nm) Microwaves Radio waves • Chloroplasts absorb light energy and convert it to chemical energy Light Reflected light Absorbed light Transmitted light Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Chloroplast The location and structure of chloroplasts Chloroplast LEAF CROSS SECTION MESOPHYLL CELL LEAF Mesophyll Stoma (pl. stomata) Intermembrane space CHLOROPLAST Outer membrane Granum Grana Figure 7.2 Stroma Inner membrane Stroma Thylakoid Thylakoid compartment Chloroplast Pigments • Chloroplasts contain several pigments – Chlorophyll a – Chlorophyll b – Carotenoids Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings Pigments – The Rainbow Catchers • Light-absorbing molecules • Absorb some wavelengths and reflect others • Color you see are the wavelengths NOT absorbed chlorophyll a chlorophyll b Wavelength (nanometers) An Overview of Photosynthesis H2O Chloroplast CO2 Light NADP+ ADP + P LIGHT REACTIONS (in grana) CALVIN CYCLE (in stroma) ATP NADPH O2 Sugar Chloroplast Organelle found inside plant cell where photosynthesis occurs. • Thylakoids - sac-like photosynthetic membranes found inside the chloroplasts, contain chlorophyll and other light absorbing pigments. Site of the Light-Dependent reactions. • Stroma - region outside the thylakoid membrane, but still inside the chloroplast. Site of the Calvin Cycle reactions. Photosynthesis is comprised of two reactions 1) Light Dependent Reactions 2) Calvin Cycle (Dark Cycle) Reactions Light-Dependent Reactions • • • • Requires light. Occurs in the thylakoid membranes. Breaks H2O molecule and produces O2. Converts ADP into ATP and NADP+ into NADPH. Light Reactions (Photolysis) • Light energy is used to split water and give – Oxygen and hydrogen – 2 H2O + light 4 H+ + O2 • Light energy is used to make ATP Electron Carrier • Molecule which carries sunlight excited electrons from chlorophyll to other chemical reactions in the cell. • Hot Coals / Fire / Tongs analogy Chlorophyll is the main synthetic pigment Plants produce O2 gas • The O2 liberated by photosynthesis is a byproduct made by splitting water (H2O) Calvin Cycle Reactions • Does not require light. • Occurs in the stroma. • Uses energy in NADPH and ATP to convert CO2 into high energy sugars. Dark Reactions (Carbon Fixation) • ATP and Hydrogen (H) are used to “fix” CO2 – To make organic molecules C6H12O6 (glucose) Variables effecting Photosynthesis • • • • Light Intensity CO2 Concentration Temperature Graphs Shape required MEASURE PHOTOSYNTHESIS • Production of Oxygen • Uptake of CO2 • Increase in Biomass (glucose, plant growth) Carbon dioxide Water Glucose PHOTOSYNTHESIS Oxygen gas Photosynthesis & Cellular Respiration Linked Processes Aerobic Respiration Photosynthesis • Energy-releasing pathway • Energy-storing pathway • Requires oxygen • Releases oxygen • Releases carbon dioxide • Requires carbon dioxide • Predominant producers on land are plants such as oak trees and cacti • In aquatic environments, algae and photosynthetic bacteria are the main food producers How Photosynthesis Moderates the Greenhouse Effect • Old-growth forests: – Are important for lumber – Are important for moderating world climates – Are homes to many species of plants and wildlife that exist nowhere else Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings • The Greenhouse effect: – Warms the atmosphere – Is caused by atmospheric CO2 Sunlight Atmosphere Radiant heat trapped by CO2 Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings