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Notes on Photosynthesis What is Metabolism? • Metabolism - All of the chemical reactions that occur within an organism. There are 2 types of metabolic reactions: 1. Catabolic 2. Anabolic Catabolic - releases energy by breaking down larger molecules into smaller molecules. Breaking Down! Example of Catabolic Reaction: Cellular Respiration - Catabolic pathway in which organic molecules are broken down to release energy for use by the cell C6H12O6 + O2 CO2 + H2O + ATP Glucose Oxygen Carbon Dioxide Water Energy Anabolic - uses energy released by catabolic pathways to build larger molecules from smaller molecules • Ever hear about “Anabolic Steroids” in the news? Building up Example of Anabolic Reaction: Photosynthesis - two-phase anabolic pathway in which the sun’s light energy is converted to chemical energy for use by the cell. CO2 + H2O C6H12O6 + O2 Carbon Dioxide Water Sun Light Glucose Oxygen What is Metabolism? The relationship of anabolic and catabolic pathways results in the continual flow of energy within organisms. Energy and Life: All living organisms require energy Living organisms are divided into 2 groups according to the way they get food: 1. autotrophs • auto = self troph = feeder a. Photosynthesis – green plants and algae b. Chemosynthesis – uses energy from inorganic chemical reactions ex. some bacteria 2. heterotrophs • hetero = other troph = feeder • animals either herbivores or carnivores • fungi (non-green; plant-like) • parasites – lives off host • saprophytes – lives on dead or nonliving organic matter • most bacteria Energy Transfer Compounds: ATP (adenosine triphosphate) – main chemical compound that living things use to store energy Why is ATP needed? 1. Light enters too rapidly for the cell to store it all in glucose 2. Energy is released in respiration too rapidly to be used ATP is made up of a nitrogencontaining compound called adenine, a 5-carbon sugar called ribose, and 3 phosphate groups Adenine Phosphate groups Ribose ≈ high energy bond adenine nitrogen base – ribose 5-carbon sugar – P≈P≈P phosphate groups ATP Structure ATP = Adenosine TriPhosphate Adenine Ribose Adenosine 3 Phosphate groups High Energy Bonds ATP ADP – adenosine diphosphate AMP – adenosine monophosphate Energy stored in ATP is released when ATP is converted into ADP + a phosphate group ATP-ADP Cycle ADP ATP Energy Adenosine diphosphate + phosphate Partially charged battery Energy Adenosine triphosphate Fully charged battery ATP is holding the ENERGY in the last phosphate…. Pop off the last one! When the last phosphate is POPPED off, it releases energy for the cell to use… & turns into ADP ATP Cycle ATP A-P≈P≈P photosynthesis respiration nerve conduction active transport ADP A-P≈P Most cells only have enough ATP to last for a short-lived activity • ATP can not be stored for long periods of time Whenever a cell needs energy it can change ADP in glucose to ATP Where does ATP come from? Mitochondria (in plants & animals) break down food (glucose) to make ATP (ENERGY). An animal (consumer) must EAT a plant to get the food (glucose). Where does the food (glucose) come from? Photosynthesis in plants ADP and ATP Video Energy Flow Chart active transport Muscle DNA synthesis contraction Protein synthesis Cell division ALL OF LIFE’s PROCESSES!!! In the bonds of ATP PLANTS BY PHOTOSYNTHESIS In the bonds of GLUCOSE ALL ORGANISMS BY CELL RESPIRATION Photosynthesis photo = light synthesis = put together (make complex from simple) Photosynthesis – the process by which green plants combine CO2 and H2O in the presence of chlorophyll and light energy to form glucose and release O2 Brief Photosynthesis Video Equation for photosynthesis: 6CO2 + 6H2O C6H12O6 + 6O2 reactants products Raw materials – CO2 and H2O (both are inorganic) Product – glucose, which is organic Photosynthesis requires light and chlorophyll • Light (radiant) energy is changed to the chemical bond (stored) energy of glucose • The light energy transferred to the electrons in the chlorophyll molecule raises the energy level of the electrons providing the energy for photosynthesis to begin • Chlorophyll acts as a catalyst Photosynthesis takes place inside the chloroplasts • contain chlorophyll • have a double layer of phospholipids and proteins • chloroplasts contain saclike photosynthetic membrane called thylakoids • thylakoids are arranged in stacks called grana • solution inside chloroplast called stroma Photosynthesis is broken down into 2 stages: 1. Light-dependent reactions – take place in thylakoid membrane 2. Calvin Cycle – uses ATP and NADPH from lightdependent reactions to produce high energy sugars (glucose) Summary of light-dependent reaction: a. Chlorophyll traps energy Kinetic (light) – stored as potential (chemical) b. Water splits 2H+ + O-2 c. ADP to ATP (stores energy) d. O2 is released Summary of Calvin Cycle: a. Does not require light b. “Fixing of a carbon in a carbohydrate” Photosynthesis: An Overview Light Water Chloroplast CO2 NADP+ ADP + P Calvin Cycle LightDependent Reactions ATP NADPH O2 Sugars Factors affecting photosynthesis 1. shortage of water 2. temperature (0º to 35º C) 3. intensity of light Photosynthesis Concept Map Write the complete chemical reaction here… reactants and products 6H2O + 6CO2 → 6O2 + C6H12O6 Photosynthesis Includes two stages Lightdependent reactions use Energy from sunlight NADPH NOTICE THIS… takes place in take place in Thylakoid membranes to produce ATP Calvin cycle Stroma of O2 goes into the atmosphere! Chloroplasts uses ATP NADPH to produce High-energy sugar goes into plant roots, for ex. Detailed Photosynthesis Video Respiration Cellular Respiration – chemical energy from glucose and other food is released in a chemical pathway to control the speed and amount • includes all the chemical reactions in which energy is released in support of cell life Where does the energy come from? the sun (stored in the chemical bonds of glucose) • photosynthesis is energy storing • respiration is energy releasing Equation for Respiration: respiratory C6H12O6 + 6O2 enzymes 6CO2 + 6H2O + 38 ATP • Respiration is the opposite of photosynthesis • Respiration occurs in the mitochondrion There are 2 stages of Cellular Respiration: 1. Glycolysis – (anaerobic) occurs in the cytoplasm • glycolysis produces 2 ATPs/glucose 2. Aerobic – (Krebs cycle and electron transport chain) occurs in mitochondrion • for every turn of the Krebs cycle 1 ATP is generated Cellular Respiration: An Overview Electrons carried in NADH Pyruvic acid Glucose Glycolysis Krebs Cycle Electrons carried in NADH and FADH2 Electron Transport Chain Mitochondrion Cytoplasm 2 2 34 Cell Respiration Concept Map 6O2 + C6H12O6 → 6H2O + 6CO2 Write the complete chemical reaction here… reactants and products Cell Respiration includes Krebs, Electron Transport Chain glycolysis uses glucose Cytoplasm to produce pyruvic acid electrons takes place in take place in Membranes (cristae) of 2 ATP Mitochondrion uses pyruvic acid, electrons oxygen to produce Carbon dioxide, water 36 ATP! (total) NOTICE THIS… goes into atmosphere If after glycolysis, oxygen is still absent – fermentation results (anaerobic respiration) 2 forms of fermentation: 1. Lactic acid – occurs in animal cells (bacteria) • accumulates in tissues – muscles, results in fatigue Examples – yogurt, buttermilk, sauerkraut, dill pickles 2. Alcohol – occurs in plants such as yeast • end product – ethyl alcohol Examples – brewing and baking In both forms of fermentation, the energy of glucose remains in the products: lactic acid and alcohol Chemical Pathways for Cell Respiration Glucose With oxygen Glycolysis =reactants = products Krebs cycle Electron transport Without oxygen Fermentation Which pathway makes more ATP—with oxygen or without? Why would a cell have the other option, then? Alcoholic or lactic acid ATP yield: Glycolysis - 2 Krebs cycle - 2 Electron transport - 34 _____________________ Total = 38 ATP stored energy is used to: 1. Build starches, fats and oils, nucleic acids, and proteins 2. Supports cell activities: a. active transport b. cell division c. nerve transmission d. biosynthesis (assimilation and photosynthesis) e. muscle contraction f. bioluminescence