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GOTTA EAT! PHOTOSYNTHESIS & CELL RESPIRATION PHOTOSYNTHESIS Photosynthesis • PLANT CELLS convert light energy to chemical energy • Carbon dioxide (CO2) requiring process • Uses light energy (photons) and water (H2O) • Producing organic macromolecules (glucose) SUN photons 6CO2 + 6H2O C6H12O6 + 6O2 glucose 6CO2 + 6H2O C6H12O6 + 6O2 REACTANTS PRODUCTS • Carbon dioxide • Glucose • Water • Oxygen • Sunlight energy Question Where does photosynthesis take place? Plants And some protists (algae) and bacteria • Autotrophs: self-producers. • Location: 1. Leaves a. stoma b. mesophyll cells Mesophyll Cell Chloroplast Stoma Stomata (stoma) Pores in a plant’s cuticle through which water and gases are exchanged between the plant and the atmosphere. Oxygen (O2) Carbon Dioxide (CO2) Guard Cell Guard Cell Chloroplast Organelle where photosynthesis takes place Stroma Outer Membrane Inner Membrane Thylakoid Granum Thylakoid Thylakoid Membrane Granum Thylakoid Space Question: Why are plants green? Chlorophyll Molecules • Located in the thylakoid membranes of chloroplasts • Chlorophyll have Mg+ in the center • Chlorophyll pigments harvest energy (photons) by absorbing certain wavelengths – (blue-420 nm and red-660 nm are most important) • Plants are green because the green wavelength is reflected, not absorbed Wavelength of Light (nm) 400 500 600 700 Short wave Long wave (more energy) (less energy) Absorption of Chlorophyll Absorption violet blue green yellow wavelength orange red Question: During the fall, what causes the leaves to change colors? Fall Colors • In addition to the chlorophyll pigments, there are other pigments present. • During the fall, the green chlorophyll pigments are greatly reduced revealing the other pigments. • Carotenoids are pigments that are either red or yellow. Photosynthesis-part 1 Two main parts (reactions) 1. Light Reaction or Light Dependent Reaction Sun light energy is used to make energystoring compounds (ATP and NADPH) Photosynthesis-part 2 Uses energy (ATP and 2. Sugar making NADPH) from stages • Calvin Cycle light rxn to make sugar (glucose) or • Light Independent Reaction or • Dark Reaction • Carbon Fixation 1. Light Reaction (Electron Flow) • Occurs in the Thylakoid membranes • Electrons flow from molecule to molecule giving off energy as it flows • This energy can be harnessed Chloroplast Stroma Outer Membrane Inner Membrane Thylakoid Granum Thylakoid Thylakoid Membrane Granum Thylakoid Space Electron Flow • When light strikes a thylakoid in a chloroplast, energy is transferred to electrons in chlorophyll. • Reaction center- chlorophyll a • Uses Electron Transport Chain (ETC) as electrons “jump” to a higher energy level • Excited electrons generate ATP and NADPH that temporarily store chemical energy ADP + P ATP NADP+ + H = NADPH Electron Flow • ADP + P • NADP+ + H ATP NADPH • Oxygen comes from the splitting of H2O, not CO2 H 2O 1/2 O2 + 2H+ Calvin Cycle • Carbon Fixation (light independent reaction) • Occurs in the stroma • Uses ATP and NADPH from light reaction • Uses CO2 • To produce glucose: it takes 6 turns and uses 18 ATP and 12 NADPH *is a process that occurs only in autotrophs (primarily plants) *requires sunlight, water and carbon dioxide *occurs in the chloroplasts with chlorophyll (green pigment) *the process converts solar energy (sunlight) into chemical energy (food) * the food produced is glucose (monosaccharide) CELL RESPIRATION Cellular Respiration: used by ALL organisms to get energy • The products of photosynthesis are the reactants for respiration. C6H1206 + O2 = ATP + CO2 +H20 • A chemical reaction that breaks down glucose to get ATP (cellular energy). Requires enzymes. • Aerobic respiration-a metabolic process that requires oxygen • Anaerobic respiration-a metabolic process that does not require oxygen Equation Comparison: 6CO2 + 6H20 + sun = C6H1206 + 6O2 • Photosynthesis • Respiration C6H1206 + 6O2 = ATP+ 6CO2 +6H20 • • Cellular Respiration: used by ALL organisms to get energy STAGE 1-Glycolysis (breakdown of glucose) STAGE 2a. Kreb’s cycle b. Electron Transport Chain A total of 38 ATP are formed for every glucose molecule Stage 1 - Glycolysis • • Anaerobic process in the cytoplasm Glucose is converted to pyruvate, producing 2 ATP and 2 NADH (electron carrier) molecules 4 ATP produced -2 ATP used =2 ATP net gain Stage 2 - Krebs Cycle & Electron Transport Chain • Aerobic respiration in mitochondria Pyruvate and NADH from Glycolysis are used to make 36 ATP molecules Krebs Cycle- • • – Produces electron carriers (NADH and FADH2) and ATP that temporarily Did you know? • Hans Adolph Krebs – In 1937 Hans Adolph Krebs discovered the details of the Krebs cycle. He had to interrupt his work and leave Nazi Germany prior to World War 2 because he was Jewish. In 1953 Krebs was awarded the Nobel Prize in Physiology or Medicine for his discovery. • 1. 2. Stage 2 - Electron Transport Chain (ETC) Electrons donated by NADH and FADH2 pass through an electron transport chain on the inner membrane of mitochondria 34 ATP are produced as H+ ions diffuse into the inner compartment through a channel protein At the end of the chain, electrons and H+ ions combine with oxygen, forming water. Fermentation: the recycling of NAD+ • Anaerobic respiration (no oxygen used) – the breakdown of glucose (glycolysis) can continue without oxygen present • Produces 2 ATP • Two types: a. alcoholic fermentation b. lactic acid fermentation Alcoholic fermentation • 1. 2. • • Performed by yeast (fungus) Pyruvate is converted to a two-carbon compound releasing CO2 Electrons are transferred from NADH to the twocarbon compound producing ethanol (ethyl alcohol) Reaction produces 2 ATP, carbon dioxide and alcohol Bakers use yeast to make dough rise; brewers use yeast to make beverages carbonated Lactic acid fermentation • Used by muscles cells during rapid exercise when oxygen is not available. • Produces 2 ATP and lactic acid/lactate . • Allows glycolysis to continue producing ATP in muscles as long as the glucose supply lasts. • Lactate can build up in muscle cells causing muscle soreness. Cellular Respiration (aerobic respiration) *process that occurs in all organisms – PLANTS & ANIMALS *requires glucose, oxygen *occurs in the cytoplasm and mitochondria *the process breaks down chemical energy (glucose) to release ATP *the products are carbon dioxide, water, and 38 ATP *aerobic respiration produces more ATP than anaerobic respiration Did you know? • ATP Molecules – The human body uses about 1 million molecules of ATP per cell per second. There are more than 100 trillion cells in the human body. That’s about 1 x 1020 , or 100,000,000,000,000,000,000 ATP molecules used in your body each second! Comparison of both …….. CELL PHOTOSYNTHESIS RESPIRATION Make food Break apart food Stores energy Releases energy Give off O2 Use oxygen Use sunlight Use CO2 Give off CO2