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7.1 Sunlight powers life. I. Obtaining Food. Autotrophs are organisms that obtain their energy through the process of photosynthesis such as green plants (aka self feeders, producers)
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I. Obtaining Food • Autotrophs are organisms that obtain their energy through the process of photosynthesis such as green plants(aka self feeders, producers) B. Heterotrophs are organisms that cannot make their own food but must obtain it from another source. Animals are heterotrophs and depend on producers for energy (aka consumers)
II. Harvesting the Energy in Food A. Plants and certain other producers use light energy to make organic molecules (energy source). 1. H2O and CO2 are the raw ingredients 2. Glucose (C6H12O6) and O2 are the products 3. Occurs by rearranging the atoms
Harvesting the energy • Cellular Respiration is the process that converts this stored organic chemical energy into a usable form ATP (adenosine triphosphate) C. Both plant and animal cells then use ATP for energy and release CO2 and H2O (fig. 7.3)
I. What is Energy? Forms of? A. The ability to perform work or to move against an opposing force. B. KineticEnergy: Energy of motion C. PotentialEnergy: Stored energy D. B and C are inversely proportional!
II. Law of Conservation of Energy A. You cannot create or destroy energy you can only change its form. B. Random molecular motion: Thermalenergy! • Caused by atoms bouncing of off each other. 2. Thermal energy transferred from warmer to cooler is called Heat. (Can’t be retrieved and put back to work that is one reason why we must continue to eat.)
Law of conservation of energy C. Stored potential energy: Chemicalenergy! • Potential to perform work is due to arrangement of the atoms and the bonds holding them together. (create bond = stored energy; break a bond = release of energy) 2. Almost all organisms use one or more of the following: Carbohydrates, Fats, and Proteins (fig. 7-5)
III. Chemical Energy at Work. A. Cells vs. Engines: both work by breaking down complex chemicals into simple ones (breaking bonds!) B. Both use O2 to accomplish this and some energy is converted to thermal (heat). (fig. 7-7) C. Cell slower and more efficient than auto engines.
IV. Calories: Units of Energy A. Amt. of energy required to raise 1g of H2O by 1 deg. C. (very small) B. We use kcal or 1,000 calories. (food labels) C. Calorimeter used to determine kcal. by burning dried food. (H2O has no kcal’s) D. Cells use enzymes not flame to release energy thus it is easier to manage
I. How ATP Packs Energy A. Draw fig. 7-9. • A=Adenine and 5-C sugar T=Tri or Three (ref. to # of P) P=Phosphate C. Each P is a neg. charged molecule since likes repel, they want to separate from each other- this contributes to the amount of potential energy avail. in each bond. (break bond=release energy)
II. ATP and Cellular Work A. Chemical reactions break ATP’s P bonds. B. Enzymes enable this to occur. C. The molecule that undergoes the change drives the work (creatine phosphate) D. Cells perform 3 types of work (fig. 7-10 1. Mechanical: muscle contraction 2. Chemical: building/breaking large molecules 3. Transport: pumping molecules across cell membrane
III. The ATP Cycle A. ATP continuously converts to ADP and back • ADP can be converted back to ATP by reattaching the P with energy from foods organic molecules • A working muscle regenerates all of its ATP molecules about once each min. or 10 million per sec.
7.4 Electrons fall from food to oxygen during cellular respiration
I. Relationship of Cellular Respiration to Breathing A. Aerobic process-requires O2 B. O2 into the cell and out C. Cellular respiration is not breathing or exchange of gasses in the lungs (fig. 7-12)
II. Overall Equation for Cellular Respiration A. Glucose+Oxygen-->Carbon Dioxide + Water + ATP B. C6H12O6 + O2 --> CO2 + H2O + ATP C. Main function is to create 38 ATP for each glucose
III. “Falling” Electrons as an Energy Source A. Falling elect. like waterfall-at the top the potential energy is high as it falls it becomes less B. Atom’s positive nucleus pulls negative electrons the closer they get the more potential energy they lose. C. Positive O2 pulls strongly on electrons in the H2 and C thus rearranging the atoms and releasing energy.
IV. Electron Transport Chain A. Controlled fall of electrons “step-by-step” walk. B. Not burst (like flame) but series of controlled reactions C. Electrons passed by carriers until O2 finally pulls electrons off at the end to form H2O and release energy to make ATP.
7.5 Cellular respiration converts energy from food to energy in ATP
I. Mitochondria Structure A. Outer membrane and Inner highly folded membrane enclosing thick fluid called matrix B. Folds increase amt. of surface area for more reactions to occur. (fig. 7-16) C. All chemical processes make up a cell’s metabolism D. Specific enzymescatalyze (speedsup) each reaction in a metabolic pathway
II. Stage I: Glycolysis (splitting of sugar) A. Occurs in cytoplasm (fig.7-17) B. 2 ATP “initial investment” to break the sugar C. 1 C6H12O6 in and 2 pyruvic acids out (3-C each) D. 2 ATP spent and 4 produced (net gain of 2)
Glycolysis 1. What are the products of glycolysis? 4 ATP molecules (net gain of 2) and 2 molecules of pyruvic acid
Glycolysis 2. Explain the terms energy-investment phaseand energy-harvest phase. Energy-investment phase refers to the part of the reaction in which two molecules of ATP are used, while energy-harvest phase describes the part of the reaction that generates four molecules of ATP.
III. Stage 2: The Krebs Cycle A. Occurs in the matrix B. Occurs twice for each glucose that entered stage one C. Produces 1 ATP and electron carrier molecules
Krebs Cycle 1. What is the overall result of the Krebs cycle? Pyruvic acid is broken down, forming carbon dioxide and releasing energy.
Krebs Cycle 2. How is acetyl CoA related to the process? One pyruvic acid molecule is converted to one molecule of acetyl CoA, which enters the Krebs cycle.
IV. Stage 3: Electron Transport Chain and ATP Synthase Action A. Occurs in the inner membrane of mitoch. B. Refer to the previous information on “falling electrons” 7-4. C. Hydrogen ions pumped across the membrane to store energy like a dam holding back water D. ATP synthases (enzymes) act like mini turbines to convert ADP back into ATP slowly. E. As many as 38 ATP’s produced for each glucose that entered glycolysis.
