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Cellular Respiration Agriculture Biology Why are photosynthesis and respiration important in agriculture? Biomass is all plant and animal matter on the Earth's surface. Harvesting biomass such as crops, trees or dung and using it to generate energy such as heat, electricity or motion, is bioenergy. Farmers try to maintain a 40:1 ratio of photosynthesis to respiration, thus increasing the amount of biomass stored by the plants. More Biomass= More Energy Why is Respiration Important? Plants use oxygen in the air (or water) to turn their food (glucose) into energy. This process of using oxygen to release energy from food is called cellular respiration Interest Grabber What kind of organisms undergo cellular respiration? All organisms including photosynthetic organisms, undergo cellular respiration as long as oxygen is present Interest Grabber How are the products of photosynthesis and respiration related? The products of photosynthesis are the starting materials for respiration Cellular Respiration C6H12O6 + 6O2 6CO2 + 6H2O + Energy (ATP) Cellular Respiration Photosynthesis vs. Respiration Photosynthesis Food synthesized (made) Energy from sun stored in glucose CO2 taken in Oxygen given off Produces sugars Requires light Occurs only in the presence of chlorophyll Respiration Food broken down Energy in glucose released CO2 given off Oxygen taken in Produces CO2 and H2O Does not require light Occurs in all living cells Chemical Pathways Cells don’t “burn” glucose They gradually release the energy from glucose and other food compounds The process begins with a pathway called GLYCOLYSIS. Glycolysis releases only a small amount of energy (net yield of 2 ATP) Glycolysis Process in which one molecule of glucose is broken in half Occurs in the cytoplasm of the cell This is an anaerobic process Produces two molecules of pyruvic acid A 3 carbon compound Glycolysis At the pathway’s beginning, 2 molecules of ATP are used up These 2 molecules should be looked at as an “investment” Gives the cell 2 net ATP molecules Glycolysis This process seems like it doesn’t create very much energy But…the cells are able to finish the process so fast, that they can create thousands of ATP molecules in just a few milliseconds Interest Grabber Some of the steps in cellular respiration take place in the membrane inside the cell structure called the mitochondrion, which has a folded inner membrane. What purpose do these folds serve? To find out the answer to this question, perform this activity. Interest Grabber Obtain two sheets of paper and a metric ruler. What is the surface area of the paper? Roll one sheet of paper into a tube lengthwise. What is the surface area of the rolled paper? Fold the second sheet of paper into a fan. Then, roll the first sheet of paper around the folded paper so it is inside the rolled paper. What has happened to the surface area of the inside of the rolled paper? What would be the value of increasing the surface area of the membrane inside a mitochondrion? The Krebs Cycle In the presence of oxygen, pyruvic acid produced in glycolysis passes to the second stage of cellular respiration The Kreb’s Cycle (also known as the Citric Acid Cycle) occurs in the mitochondria of the cell Named after Hans Krebs 1937; he discovered the details of what is now known as the Krebs Cycle Krebs Cycle During the Krebs cycle the following occurs Pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions NADH, FADH2, CO2 and ATP A total of 2 ATP are created from this stage Krebs Cycle Every time you exhale, carbon dioxide is released This carbon dioxide is produced by the Krebs Cycle The ATP produced is used for cellular activities Electron Transport Electrons passed around during the Krebs Cycle to the electron transport chain The electron transport chain uses the high-energy electrons from the Krebs Cycle to convert ADP into ATP A total of 32 ATP are created in the mitochondria during this stage of resp. Electron Transport Chain Fermentation If oxygen is not present, glycolysis is followed by a different pathway The combined process of this pathway and glycolysis is called FERMENTATION Fermentation releases energy from food molecules in the absence of oxygen Fermentation There are two types of fermentation Alcoholic Fermentation Lactic Acid Fermentation Alcoholic Fermentation Produces carbon dioxide and ethyl alcohol as wastes This is what is produced when yeast is used to make bread When the yeast in the dough runs out of air, it begins to ferment and produces bubbles of carbon dioxide to rise the dough Pyruvic Acid + NADH = Alcohol + CO2 + NAD+ Lactic Acid Fermentation Produces lactic acid and NAD+ as wastes Produced in your muscles during rapid exercise when the body cannot supply enough oxygen to the tissue Pyruvic Acid + NADH = Lactic acid and NAD+ Quick Energy vs. Long Term Energy The body provides enough ATP to last about 90 seconds-Quick Energy Enough time for a runner to finish a 200-300 meter dash Fermentation produces lactic acid as a by product Getting rid of lactic acid requires oxygen Thus a runner breathes heavily at the end of the race to rid the muscles of lactic acid that built up Quick Energy vs. Long Term Energy How about when you need energy for a long time? The body relies on cellular respiration to release energy more slowly This is why athletes must pace themselves over a long race---why? To allow oxygen to fuel the process of cellular respiration and make more ATP!!!