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Lecture 3

2012.02.11 - Bio 1202 Lecture 3 Review Notes.docx

2 Pages

Course Code
Biology 1202B
Gardiner/ Murphy

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Lecture 3  Bioenergetics – the study of energy in living system (environments) and the organisms that utilize it  Potential energy – energy that matter occupies because of it’s location, arrangement, or position (Ex: Water behind a dam)  Kinetic energy – energy in the process of doing work (energy of motion) (Ex: heat)  Laws of Thermodynamics: o First Law – energy cannot be created or destroyed, but only converted to other forms (thus the amount of energy in the universe is constant) o Second Law – all energy transformation are inefficient because every reaction results in an increase in entropy, and the loss of usable energy as heat  Entropy – amount of disorder in a system  Measures the energy that is no longer available to perform useful work within the current environment  Free Energy – the portion of a system’s energy that can perform work when the temperature is uniform  ∆G = the change in free energy in a system changing from one state to another  Endergonic reactions – chemical reactions requiring a net input of energy (Ex: photosynthesis) o ∆G > 0  Exergonic reactions – chemical reactions that release energy (Ex: cellular respiration) o ∆G < 0 (spontaneous reactions)  Coupled reactions – use exergonic reactions to power an endergonic reaction  Redox reactions – chemical reactions that involve the transfer of one or more electrons from one reactant to another o This electron transfer is called oxidation-reduction or redox reactions o Electron donor = reducing agent o Electron acceptor = oxidizing agent  Photosynthesis – reduction of carbon dioxide into sugars and the oxidation of water into molecular oxygen o Redox reaction o Reverse reaction (respiration) – oxidizes sugars to produce carbon dioxide and water  Cellular Metabolism – the total sum of chemical activity of all cells o Anabolic pathway – metabolic reactions that consume energy (endergonic) to build complicated molecules from simpler compounds (Ex: photosynthesis) o Catabolic pathway – metabolic reactions that release energy (exergonic) by breaking down complex molecules into simpler compounds (Ex: cellular respiration)  Anabolic reactions = synthesis reactions  Catabolic reactions =
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