CHAPTER 7 - Making Macromolecules (MOL S11)

CHAPTER 7 - Making Macromolecules (MOL S11) - Chapter 7:...

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Chapter 7: Making Macromolecules 1 CHAPTER 7: MAKING MACROMOLECULES 7.1 INTRODUCTION: What are the molecular components of a cell? A living cell contains molecules ranging in size from the very small to the very large. 7.2 MONOMERS AND POLYMERS 7.2.1 Monomers and Polymers A large number of monomers can be chemically linked to produce a polymer. 7.2.2 Polyethylene This polymer is formed by repeatedly linking molecules of ethylene via an addition reaction. Box 7.1 Polymers and Plastics 7.2.3 Polyesters and Polyamides These polymers are formed by condensation reactions and named for linkages that are formed. 7.2.4 Classifying Polymer Diversity Polymers are classified by monomer type(s), the type of joining reaction, and the resulting linkages. 7.3 BIOLOGICAL POLYMERS 7.3.1 Three Classes of Biological Polymers The three main classes of biological polymers are polypeptides, polynucleotides, and polysaccharides 7.3.2 Proteins (polypeptides) Proteins are polymers of amino acids and perform most of the essential functions of the cell. 7.3.3 DNA (polynucleotides) Polynucleotide strands are used to make DNA and RNA molecules in the cell 7.3.4 Sugars (polysaccharides) Starch is a polysaccharide formed by linking many copies of a glucose monomer. Box 7.2 Why can humans digest starch but not cellulose? 7.4 CHAPTER SUMMARY
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Chapter 7: Making Macromolecules 2 7.1 INTRODUCTION: What Are The Molecular Components of a Cell? In Chapters 4 and 5 we examined how atoms can bond with each other to form a remarkable diversity of molecules. Chapter 4 focused on hydrocarbons – molecules made from only hydrogen and carbon atoms – while Chapter 5 showed how the diversity of molecular structures is greatly expanded by including heteroatoms such as oxygen, nitrogen, sulfur, and phosphorus. Equipped with this knowledge, we can now ask an important question: What are the various molecular components of a living cell? We can begin to formulate an answer by decomposing a single E.Coli cell into its molecular constituents, which is similar to disassembling an automobile into its mechanical parts. E. Co li is a single-cell bacterium, one of the simplest forms of life. If we treat this cell with a detergent (similar to those used in dishwashing liquids), the cell membrane ruptures and the chemical constituents of the cell are released. The various components of the mixture can then be identified by analytical techniques. This chemical dissection of an E.Coli cell is illustrated in Figure 7.1; the results of the chemical analysis are shown as a pie chart according to percent contribution by mass. You can see immediately that the largest component of the cell is water, which accounts for 70% of the total mass. Most (but not all) biological molecules reside in this aqueous environment, which has important consequences for their structure and function. After water, the next largest contribution to the cell comes from proteins . These are an essential group of molecules in the cell and the name derives from the Greek for “first in importance.” Proteins
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CHAPTER 7 - Making Macromolecules (MOL S11) - Chapter 7:...

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