Energy101 - Energy Flow in Cells - 1 Thousands of chemical...

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Energy Flow in Cells - 1 Thousands of chemical reactions occur in our cells and tissues to keep us alive (and hopefully healthy). We have discussed some of the molecules of living organisms (carbohydrates, lipids, proteins, etc.) in the context of the functions they perform in cells and tissues. These coordinated, controlled and orderly activities of cells collectively comprise the metabolism of living organisms. Much of metabolism involves energy transfer so it is helpful to have a common knowledge base about energy. The energy used in metabolism is chemical energy , the energy of electrons. This energy is used to build and maintain our cells and tissues, to move materials into and out of our cells, to process fuel molecules - to do the work of the cell. We will briefly look at the physical laws that govern energy flow, how energy flow relates to chemical reactions and how living organisms control the chemical reactions that occur in their cells and tissues. Since enzymes catalyze our chemical reactions it's important to take a look at enzyme activity, too. Defining Energy Energy is often defined as the capacity to do work. The two fundamental types of energy are kinetic (energy at work, or the movement of energy) and potential (stored energy waiting to do work, such as the energy in the bonds of chemicals). Potential energy is energy that matter has because of its structure or location. The water stored behind a dam has potential energy because of its location. Chemical bonds have potential energy because of their structure. The water flowing through the turbines of a dam has kinetic energy . Both kinetic and potential energy can be found in many forms, such as electrical, light, chemical, heat, and mechanical. Under the right conditions, energy can be transformed from one type to another and from one form to another. This is a good thing, since different kinds of work require different kinds of energy, and as it applies to living organisms, it is often thought of as energy flow. Without energy flow, we would have no life on earth. To make sense of this we have to understand both the quantity of energy available and the usefulness of that energy to do work, which is the study of thermodynamics , the field that studies energy transformations. There are two laws: one addresses the quantity of available energy and the second addresses the usefulness or availability of energy to do work. In addition, thermodynamics involves a system and its surroundings . The matter being studied is the system, and everything outside of the system is the surroundings.
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Energy Flow in Cells - 2 The Two Laws of Thermodynamics The First Law of Thermodynamics states the amount of energy in any process is constant, meaning that energy can neither be created nor destroyed by ordinary processes. But energy can be, and is, converted from one form to another and between potential and kinetic. When we apply this law to living organisms (or any system) we say that the total
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This note was uploaded on 02/27/2009 for the course SC 424111 taught by Professor Various during the Summer '09 term at Bentley.

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Energy101 - Energy Flow in Cells - 1 Thousands of chemical...

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