BiologicalMolecules101

BiologicalMolecules101 - Biological Molecules - 1 Molecules...

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Biological Molecules - 1 Molecules of Living Organisms We have mentioned that all organisms, from bacteria to Douglas fir trees to humans share a common molecular structure; it's part of the unity of life. The cells and tissues of virtually all organisms are made up of the same basic molecules. Many of these are substances with which we are familiar: our carbohydrates, lipids, proteins and the nucleic acids. These molecules are all compounds with a "backbone" of carbon, or more specifically carbon–hydrogen molecules, which are called hydrocarbons. The incredible versatility of carbon accounts for the multitude of different organic molecules, built from the common backbones, which are found in different kinds of organisms. In chemistry, molecules with a backbone of carbon that also contain hydrogen are called organic molecules. The other atoms and molecules necessary for life are inorganic. Besides carbohydrates, proteins, lipids and nucleic acids, our vitamins are considered to be organic. (Water, oxygen, carbon dioxide and the minerals needed to sustain life are inorganic.) Our organic compounds are responsible for such things as: ± Fuel (energy to do cell work and keep us alive) ± Structure ± Metabolism ± Fuel Storage ± Genetic Information Before understanding the structure of the major groups of compounds of living organisms, we should first study the element, carbon, what a hydrocarbon is, and also study the molecules called functional groups, which bond to hydrocarbons, altering the chemical nature of the resulting compound. Properties of Carbon Carbon is one of the atoms (elements) that forms covalent bonds (joins with other atoms) to become stable. Each carbon atom makes 4 bonds Carbon may make bonds with other carbon atoms forming chains, branching chains or rings of linked carbon atoms.
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Biological Molecules - 2 Carbon may also bond to different kinds of atoms, most notably hydrogen. In fact, the basic carbon compound is a hydrocarbon, formed from carbon and hydrogen. Properties of Hydrocarbons Hydrocarbons, like carbon, typically vary in: The number of carbons on the chain Straight, branching chains or ring compounds What is attached to the carbon chain Most hydrocarbons have very similar properties. For example the C—H bond is energy rich; so hydrocarbons make good fuels (methane, propane, butane, methanol, alcohol) Hydrocarbon variations that differ only in the arrangement of atoms are called isomers. Isomers are very important in biology, and we shall see many examples of isomers. There are three types of isomers: structural, geometric and enantiomers. (We don't need to worry much about these details in Biology 101, though.) Structural isomers vary in their covalent bonding arrangement.
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Biological Molecules - 3 Geometric isomers share common covalent bonding, but have different shapes. The differing shape of geometric isomers can dramatically affect their biological function. (This is sometimes called the cis-trans difference.) Cis-trans changes occur when one partially hydrogenates fats, forming
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BiologicalMolecules101 - Biological Molecules - 1 Molecules...

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