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Chapter 8: Photosynthesis 8.1 Energy of Life (p. 201) I. Autotrophs and Heterotrophs A. Plants and some other types of organisms are able to use light energy from the sun to produce food. B. Energy is essential to life; all living organisms must be able to obtain energy from the environment. C. Plants are able to trap light energy and use it. 1. Autotrophs = organisms such as plants that are able to make their own food D. Other organisms must eat food to obtain energy. 1. Heterotrophs = organisms such as animals that must obtain energy from their food. II. Chemical Energy and ATP A. Work and the need for energy. (Fig 8-3) 1. Many cellular processes require energy. Ex. Active transport, cell division, locomotion of cell, are some examples. 2. ATP (adenosine triphosphate) is a molecule in your cells that is the source of energy. 3. This energy is stored in the chemical bonds of ATP. 4. ATP is composed of: a. one adenosine molecule (which is the sugar ribose connected to an adenine molecule) b. three phosphate groups III. Forming and Breaking Down ATP 1. The energy of ATP becomes available to a cell when the molecule is broken down. 2. When ATP is broken down energy is released and the resulting molecule is ADP (adenosine diphosphate) 3. ATP is broken down into ADP when the chemical bond between the second and third phosphate group in ATP is broken. 4. At this point ADP can form ATP again by bonding with another phosphate group. 5. This process creates a renewable cycle. (fig. 8-3) *As long as phosphate groups are available, a cell can create ATP whenever it needs to. A. How cells tap into the energy stored in ATP' 1. When ATP is broken down and the energy is released, it must be captured and used or it is wasted and given off as heat. 2. ATP ADP + P + Energy 3. To access the energy locked up inside an ATP molecule it usually binds to a protein (or enzyme). There is a specific binding site where ATP fits into and the protein will aide in the removal of the third phosphate group. IV. Uses of Cell Energy 1. Making new molecules 2. Maintaining homeostasis 3. Eliminating wastes Biology A-D Answer questions: 1-3 PAP: 1-5 8.2 Photosynthesis: An Overview Investigating photosynthesis Van Helmont: Conducted an experiment in the 1600’s and determined that plants grew by taking materials out of the soil Joseph Priestly determined that there was a substance in the air that was required for a candle to continue burning. When that substance was used up, the candle went out. That substance was oxygen. Han Ingenhousz: determined that plants needed the substance in the air to live, but only when they were exposed to light. II. Trapping Energy from Sunlight A. Plants use energy in the form of ATP as well. Since sunlight is not available all the time they must harvest the suns energy and store it for later use. B. Photosynthesis = the process that uses the sun’s energy to make simple sugars. 1. These simple sugars are then converted into complex carbohydrates, such as starches, which store energy. C. Photosynthesis happens in two phases 1. Light-dependent reactions – convert light energy into chemical energy (ATP molecules) 2. Light-independent reactions- produce simple sugars (like glucose) **** Bottom Line**** * Photosynthesis uses the energy of the sunlight to convert water and carbon dioxide into high energy sugars and oxygen. **General Equation for photosynthesis** 6CO2 + 6H2O + sunlight C6H12O6 + 6O2 * Carbon dioxide + Water → Sugars + Oxygen 8.3 The Reactions of Photosynthesis I. Inside the chloroplast (include figure 8-6 in your notebook) A. Each Chloroplast within each plant cell has the following parts 1. stroma = the space outside the thylakoid membranes 2. granum – a stack of thylakoids 3. photosystems = clusters of pigment and protein that absorb light energy and are found in saclike photosynthetic membranes.