08Feb_10 - Biological Science I Tuesdays and Thursdays...

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Biological Science I Tuesdays and Thursdays 8:00-9:15, HCB 102 Mondays 5:15-6:15, KIN 1024 08 February 2010 – Lecture 5 By the end of today’s lecture you should be able to: Distinguish between the following pairs of terms: catabolic and anabolic pathways; kinetic and potential energy; open and closed systems; exergonic and endergonic reactions In your own words, explain the second law of thermodynamics Explain in general terms how cells obtain the energy to do cellular work Explain how ATP performs cellular work Explain why an investment of activation energy is necessary to initiate a spontaneous reaction Describe the mechanisms by which enzymes lower activation energy Describe how the activity of an enzyme is egulated 1. Energy and life a. The living cell is a miniature chemical factory where thousands of reactions occur b. The cell extracts energy and applies energy to perform work c. Some organisms even convert energy to light, as in bioluminescence 2. An organism’s metabolism transforms matter and energy, subject to the laws of thermodynamics a. Metabolism - a.i. totality of an organism’s chemical reactions a.ii. an emergent property of life that arises from interactions between molecules within the cell b. A metabolic pathway b.i. begins with a specific molecule and ends with a product b.ii. Each step is catalyzed by a specific enzyme c. Catabolic pathways c.i. release energy by breaking down complex molecules into simpler compounds c.ii. Cellular respiration, the breakdown of glucose in the presence of oxygen, is an example of a pathway of catabolism d. Anabolic pathways d.i. consume energy to build complex molecules from simpler ones d.ii. The synthesis of protein from amino acids is an example of anabolism e. Bioenergetics e.i. the study of how organisms manage their energy resources e.ii. Energy is the capacity to cause change e.iii. Energy exists in various forms, some of which can perform work e.iii.1. Kinetic energy is energy associated with motion e.iii.2. Heat (thermal energy) is kinetic energy associated with random movement of atoms or molecules e.iii.3. Potential energy is energy that matter possesses because of its location or structure 1
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Biological Science I Tuesdays and Thursdays 8:00-9:15, HCB 102 Mondays 5:15-6:15, KIN 1024 08 February 2010 – Lecture 5 e.iii.4. Chemical energy is potential energy available for release in a chemical reaction e.iii.5. Energy can be converted from one form to another 3. The laws of energy transformation a. Thermodynamics is the study of energy transformations b. A closed system, such as that approximated by liquid in a thermos, is isolated from its surroundings c. An open system, energy and matter can be transferred between the system and its surroundings d. Organisms are open systems e. The First Law of Thermodynamics - the principle of conservation of energy e.i. The energy of the universe is constant: e.ii. Energy can be transferred and transformed, but it cannot be created or destroyed f. The Second Law of Thermodynamics f.i.
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