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Exam 2 notes - 1 Energy is a The capacity to do work b Two...

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1. Energy is a. The capacity to do work b. Two types: i. Potential - stored energy in the form of 1. Chemical bonds 2. Electrical energy 3. Positional energy ii. Kinetic - energy of movement 1. Light 2. Heat 3. Electricity 4. Movement of objects 2. The Law of Thermodynamics a. Energy cannot be created nor destroyed but can be transformed into a different kind of energy (conservation of energy) b. When energy is converted into another form, the amount in a useful form is decreased (conversion is not 100% efficient) c. When energy is converted into another form, the new form is less organized than the original form (entropy increases) 3. The original source of energy for life on Earth? a. The Sun! (some energy is captured from other sources) b. Energy is produced by the sun (nuclear reactions) and travels to earth in the form of light energy (and heat) c. Energy is transferred from photosynthetic organisms to other organisms—energy in the form of chemical bonds stored in the glucose molecule 4. Energy in Chemical Reactions a. Reactants are converted into products b. Some reactions are endergonic i. Require energy to make products c. Some reactions are exergonic i. Release energy when making products 5. All reactions, endergonic and exergonic, require some initial energy to start a. Activation energy (can be large or small) b. Exergonic reactions have small activation energy requirements, and the products are at much lower energy than the reactants (energy is released) c. Endergonic reactions have large activation energy requirements , and the products are at much higher energy than the reactants 6. In biology many reactions are coupled a. Coupled reactions have one exergonic reaction and one endergonic reaction b. The endergonic reaction uses excess energy released by the exergonic reaction c. In ATP coupled reactions, the excess energy released in exergonic reactions is stored in the bonds of the molecule ATP i. ATP then travels to other parts of the cell to be used to power endergonic reactions 7. ATP Synthesis= the manufacture of ATP a. ATP = Adenosine triphosphate (nucleic acid) b. Energy released by exergonic reactions is used to add a phosphate group to adenosine diphosphate (ADP) to make ATP c. Energy is stored in the chemical bond that joins the third phosphate to the rest of the molecule d. ATP can then travel to other parts of the cell to be used for endergonic reactions 8. ATP Breakdown a. When ATP is used for endergonic reactions, the phosphate is removed,
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releasing ADP and a free phosphate along with energy. b. The ADP and phosphate groups can later be recycled to make new ATP
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