micro(bio) - Structure and Function of Macromolecules - 1...

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Structure and Function of Macromolecules - 1 As we stated in our carbon introduction, the majority of the molecules found in living organisms are based on carbon, (along with nitrogen, oxygen and hydrogen in the functional groups). Their specific chemical properties are, to a large extent, determined by the functional groups attached to the carbon backbones. Many of our molecules are large, and are assembled from smaller molecules that are either identical to each other, or similar to each other. These large molecules are called macromolecules or polymers . The "building blocks" of these polymers are called monomers or subunits , and have a common structure. Because our polymers are large molecules, and based on carbon, we can get a great diversity of them from just a few small monomers, by varying number, sequence and bonding arrangements. Our biological macromolecules are grouped into four categories: proteins, nucleic acids, lipids and carbohydrates. We shall discuss structure and functions of each group. Most of our biological molecules are assembled or broken down using the same type of chemical reaction, one which involves adding or removing water molecules. Macromolecules are formed from their subunits by removing molecules of water (a hydrogen (-H) from one subunit and the hydroxyl (-OH) from the second) to join the subunits together. This is called a dehydration synthesis , or condensation . When larger molecules are broken down, such as in digestion, water molecules are added in to break the macromolecules into their subunits, a process called hydrolysis. The enzymes that facilitate digestion are called hydrolytic enzymes. Let's now look with some detail at the major compounds of living organisms. We shall look at Proteins, Lipids and Carbohydrates, and briefly the fourth: Nucleic Acids. We will deal with the nucleic acids in depth during our unit on molecular genetics.
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Structure and Function of Macromolecules - 2 Amino Acids and Proteins Proteins are very large molecules composed of combinations of about 20 different amino acids. The precise physical shape of a protein is very important for its function. A single cell may have 10,000 or more different proteins. This diversity of proteins is essential for the functioning of each cell in a living organism. It has been estimated that there may be over 100,000 different kinds of proteins. As much as half of the non-water component of a typical cell can be protein. Functions of Protein Enzymes Globular proteins that facilitate chemical reactions. Defense Proteins Antibodies Protein toxins Transport Proteins Plasma membrane proteins carry substances through membranes or form channels or pumps for passage Oxygen carrier in circulation (hemoglobin) Mineral protein carriers (iron, zinc) Structural/Support Proteins (Fibrous proteins) Connective tissue in animals (collagen – the most abundant vertebrate protein) Webs, cocoon s and other arthropod structures Hair, nails horns, etc. (keratin)
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This note was uploaded on 02/19/2010 for the course BIOL 2273 taught by Professor Trevorrook during the Spring '09 term at Adams State University.

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micro(bio) - Structure and Function of Macromolecules - 1...

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