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Sunlight Powers Life Obtaining “Food” • Biologists classify organisms according to how they obtain food • Autotrophs “self-feeder” – Organisms that make their own “food” • Examples: plants – Also called producers Obtaining Food • Heterotrophs “other eaters” – Organisms that cannot make their own food • Examples, humans and other animals – Also called consumers Obtaining Food • Types of Heterotrophs – Herbivore – plant eater – Carnivore – animal eater – Omnivore – plant and animal eater – Decomposer – breaks down organic matter fungi bacteria Harvesting Energy • Organisms harvest energy in several ways: • Cellular Respiration – Converts chemical energy from organic molecules (food) into usable energy • By heterotrophs • Photosynthesis – Plants use light to convert water and carbon dioxide into energy (a sugar) • By autotrophs » NOTE: there are some organisms that will use neither light nor organic matter and make energy through chemicals Energy Flow • Energy flows through an ecosystem from the sun to autotrophs and then to heterotrophs. Intro. To Energy • Energy is the ability to do work. • Energy cannot be created or destroyed. It can be converted from one form to another. – First Law of Thermodynamics Intro. To Energy How do organic compounds in food provide energy? • Remember, organic molecules are things like, carbohydrates, fats, and proteins – During chemical reactions, bonds break releasing ENERGY (and the resulting atoms can also be rearranged) – This ENERGY is now available to do work. Intro. To Energy Your body uses ALL types of organic molecules to help produce its energy. So consume some proteins, fats and sugars Putting Chemical Energy to Work • In cells complex molecules (like carbohydrates and proteins) are broken into smaller molecules. – Like an engine uses chemical reactions to power a car. Cells break down food into energy. How ATP Packs Energy • The energy of food originally comes from the sun. • The chemical energy stored in organic food, must first be converted to energy stored in another molecule….. ATP Adenosine triphosphate The principal chemical compound that cells use to store energy. The triphosphate adenine The adenosine 3 phosphate groups make up the “tail” – it is the source of energy used for most cellular work Ribose (5-C sugar) As Bonds are broken between the phosphates, energy is released ATP and Cellular Work • The process of breaking bonds and transferring energy is sped up by…. Enzymes !!! Cellular Respiration • All the cell’s chemical processes make up the cell’s metabolism. Cellular Respiration • Is the process that releases energy by breaking down organic (food) molecules in the presence of oxygen • The equation for cellular respiration • C6H12O6 + 6 O2 6 CO2 + 6 H2O + Energy (ATP) Cellular Respiration • What does the equation tell us? – C6H12O6 is a carbohydrate and enters into the reaction (the cell) – O2 is oxygen and enters into the cell – CO2 is carbon dioxide is produced and leaves the cell – H2O is water and is produced – ATP is energy and is produced to do work • We will follow these through cellular respiration and see where they enter and leave during the process. Cellular Respiration Road map eelectron carriers eElectron carriers Pyruvic acid Glucose Glycolsis Krebs Cycle Electron Transport Chain Cytoplasm Mitochondrion ATP ATP ATP Cellular respiration takes place in several steps so energy is released a little at a time, otherwise it would be lost as heat and light Cellular Respiration Road map REMINDER: • The energy made during Cellular Respiration is carried in a molecule called ATP • Adenosine Triphosphate You will see the energy of ATP shown as this star burst. ATP Glycolysis -Glycolysis is the first step in breaking down a glucose molecule. (C6H12O6 ) -Takes place in the cytoplasm of the cell. -Does NOT require oxygen -Produces a small amount of ATP -electron carriers are produced (which store energy for later) -Glucose is broken downe-to Pyruvate 2 ATP are required to start the process 4 total are produced. Only 2 are gained (4-2 = 2) 2 ATP gained cytoplasm The Krebs Cycle • The Krebs Cycle finishes the breakdown of Pyruvate • Pyruvate, produced during Glycolysis enters the Krebs Cycle • This happens only in the presence of oxygen. The Krebs Cycle -Takes place in the Mitochondria (within the matrix) -Pyruvate is broken down -CO2 (carbon dioxide) is produced as a waste -2 ATP are gained -electron carriers are produced The Krebs Cycle 2 ATP 2 ATP The Krebs Cycle • A Review CO2 produced as waste Pyruvate enters Electron carriers produced e- (electrons) carry energy (like ATP) We will see how the energy in the electrons is utilized in the next step Krebs Cycle ATP CO2 produced as waste Electron Transport Chain • This is the final stage of cellular respiration • Takes place in the inner membranes of the mitochondria Electron Transport Chain • The chain uses electrons from glycolysis and Krebs to make Lots of Energy ! -Oxygen is required for this -Water is produced as waste -Generates 34 ATP ee-eeGlycolysis 2 ATP Krebs 2 ATP Electron Transport 34 ATP Electron Transport Chain The “fall” of electrons creates Lots of energy • H+ Intermembrane space Inner membrane matrix H+ H+ H+ H+ H+ ee- H+ H+ H+ O2 H2O Oxygen is required to “pull” the electrons down the chain ATP H+ Adding up the ATP Molecules • From Glycolysis ----------- 2ATP • From Krebs ----------------- 2 ATP • From Electron Transport 34 ATP Total 38 ATP Harvesting energy without oxygen • What happens when your body is forced to work without oxygen? – For example, what happens when you sprint to catch a bus? – Your leg muscles are forced to work without enough oxygen because you are spending ATP more quickly than your lungs and bloodstream can deliver oxygen to your muscles for cellular respiration. • Fortunately, some of your cells can produce ATP and continue working for short periods without oxygen. Fermentation • Fermentation – makes ATP without using oxygen. • Fermentation makes ATP directly from glycolysis. • By burning enough glucose (2ATP), fermentation can regenerate enough ATP molecules for short bursts of activity. – Like sprinting to catch a bus Fermentation – Two types depending on the organism Lactic Acid and Alcohol Anaerobic respirationno oxygen Alcohol or Lactic Acid Aerobic respiration – with oxygen Pyruvate Krebs Cycle Lactic Acid Fermentation in Humans • Fermentation in muscle cells converts the glucose to pyruvic acid, but then produces a product called lactic acid. • The lactic acid then diffuses into the blood. – The lactic acid is the “burn” you feel in your muscles. Lactic Acid Fermentation in Microorganisms • Fungi and Bacteria in an anaerobic environment (an environment without oxygen)are forced to ferment sugar and other foods. – Gives sour taste to foods like yogurt and cheeses, also creates sauerkraut and pickles Alcohol Fermentation • When Yeast (some bacteria) are kept in an anaerobic environment they will produce ALCOHOL and release carbon dioxide gas. – Carbon dioxide makes bread rise. Some products produced by fermentation