Notes for Exam 2

Notes for Exam 2 - Biology 1001 Notes Chapter 6: Energy...

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Biology 1001 Notes Chapter 6: Energy Flow in Cells 9/18/07 What is Energy? Energy = the capacity to do work a. Kinetic energy = energy of movement Examples: i. Light ii. Heat iii. Electricity b. Potential energy = stored energy Examples: i. Chemical energy i. Batteries ii. Positional Laws of Thermodynamics 1 st Law: Conservation of energy: amount of energy in a system remains constant 2 nd Law: When converted from one form to another, useful energy decreases -Entropy (a measure of disorder) increases Example: Chemical energy in the form of gasoline (low entropy) Put it in the car and turn the car on (high entropy) due to the usage of the gasoline Gasoline is going from one state to another, but not all gasoline is used to make the car move Energy Flow on Earth Energy input from the sun Photoautotrophs (Plants, other producers) Heterotrophs (consumers, decomposers) ….(missed last sentence)
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Quiz: Why is it possible for living organisms to comply with the 2 nd law of thermodynamics? How Does Energy Flow in chemical Reactions? 1. Chemical reaction : forming and breaking chemical bonds among atoms 2. Reactants: starting materials 3. Products: result of the reaction Exergonic Reactions Energy Released A + B C + D (High Energy Reactants) (Low Energy Products) Example: Glucose and oxygen combine (High energy reactants) Water + Carbon Dioxide (Low Energy Products) (so you breath in oxygen and breath out carbon dioxide) Endergonic Reactants (opposite of Exergonic Reactions) C + D A + B (Low Energy Reactants) (High Energy Products) Example: Photosynthesis Energy Supplied (from the sun) Water + Carbon Dioxide (Low Energy Reactants) Exergonic Reactions (Fig. 6-2a) Burning glucose (sugar): an exergonic reaction Activation energy (needed to start the reaction) needed to ignite glucose Endergonic Reactions (Fig. 6-2b) Photosynthesis: an endergonic reaction Coupled Reactions (Fig. 6-3) Exergonic reaction: ATP 100 units energy released + ADP + p Endergonic reaction: released muscle + 20 units of energy contracted muscle Coupled reaction: released muscle + ATP contracted muscle + 80 units of energy released as heat + ATP + p Quiz: Which reaction is NOT an exergonic reaction? How is Cellular Energy Carried Between Coupled Reactions? Phosphorylation and ATP (Fig. 6-4)
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Synthesis of ATP: Readily Available Energy A-P~P (ADP) + Energy + Pi (Inorganic) = A-P~P~P (ATP) Breakdown of ATP: Releasing Energy for Work A-P~P~P (ATP) = Energy~P A-P~P (ADP) Coupled Reactions within Living Cells (Fig. 6-5) Electron Carriers (Fig. 6-6) How Do Cells Control Their Metabolic Reactions? Metabolism
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Notes for Exam 2 - Biology 1001 Notes Chapter 6: Energy...

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