02_PropertiesofLifeFinalized

02_PropertiesofLifeFinalized - 02 Properties of Life...

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Copyright 2006 Hasbro Inc. . 0 2 Properties of Life
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Since time immemorial, humankind has been studying life: animal life, plant life, human life. As far as we can ascertain, only our species, Homo sapiens, has the ability to look both inward and outward in order to seek the definition of life. We have a unique self-consciousness that is not present in other living forms. For example, while I write this chapter, I am thinking abstractly about myself and the human species. No other living being can do this. There is universal agreement that all life forms - ours included - have two major properties: reproduction and energy capture and utilization, or metabolism. Of these two properties, the capture of energy has the highest priority since without it reproduction cannot occur. Metabolism and reproduction are directed and orchestrated by molecules that are found in all living systems - genetic material: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). These molecules will be discussed in detail in a later module, but they are common to all biological systems of reproduction and energy capture and utilization are coordinated by DNA/RNA found in all living systems. In this module, we will discuss the following properties of life: energy capture and use, reproduction, chromosomal change, homeostasis, and death. 0 2 Properties of Life
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Energy Capture and Utilization in Living Systems: Oxidation/Reduction All forms of life capture, ingest and utilize energy from a source we call food. The entire biological system involves the transfer of energy from one source or another. Nothing is sacred. Food is everywhere! Bacteria thrive in our intestinal tract and get their energy from our undigested food. Tyrannosaurus Rex , the fearful dinosaur, long since gone, and you eating your fish taco used and use similar processes of mechanically breaking down food by chewing it and then further breaking it down with chemicals found in the intestine. So what is the purpose of this? The purpose is to capture the chemical energy found in hydrogen bonds. The bottom line is that all living systems ultimately strip hydrogen ions and electrons from the food that they ingest and use this energy to power their cells. Stripping the energy from food is a chemical process. Whether you are a bacteria living in a small pond, a hyena chewing on the remains of a kill on the plains of Africa, or human eating popcorn at the movies, the ultimate chemical processes are the same. A group of interconnected proteins called enzymes strip hydrogen ions and electrons from the chemicals that make up our food. These hydrogen ions and electrons indirectly produce ATP, a compound that powers all chemical reactions in every cell. The stripping or loss of electrons or hydrogen ions is called oxidation and the addition of electrons or hydrogen ions is called reduction. This may seem countersensical, but the reason that gaining an electron is called reduction is because a change in electrons changes the electrical charge of the molecule. All life activities depend on these two processes. We oxidize our food to
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02_PropertiesofLifeFinalized - 02 Properties of Life...

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