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CHAPTER 5 THE STRUCTURE AND FUNCTION OF MACROMOLECULES Section A: Polymer principles Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Warm-Up • Draw three water molecules and label: • Covalent bonds • Charges • Hydrogen Bonds • Describe how the three properties of water (thermal, cohesive and solvent) are important for biological organisms. Day 2 - Polymers • AIM: DWBAT describe polymerization and its importance in biochemistry. • Homework: Flashcards 8-12. Packet pgs. 5-6. Quick Check – Hands Up! What is a consequence of hydrogen bonding between water molecules? A. Water is able to evaporate easily. B. Water is transparent. C. Water can dissolve carbohydrates, lipids and proteins. D. Ice melts and water boils at relatively high temperatures. Inorganic Molecules • Typically smaller than organic molecules • Ionic compounds, small covalent compounds (CO2, H2O, etc.) • Metal ions important in transmission of nerve signals • Elements include metals and non-metals CARBON • Tetravalent 4 different bonds variety isomerism • Forms long chains (polymers) macromolecules and ring structures • Tetrahedral structure 3-D variation optical isomerism Organic compounds • Compounds containing carbon found in living organisms • Not including carbonates, hydrogen carbonates, CO2 or CO • Often based upon a skeleton of carbon • An infinite variety possible • Evolution has chosen a few for use in living organisms • There are four principal groups: sugars, fatty acids, amino acids and nucleotides Organic Molecules • A cell is mostly water (inorganic). • The rest of the cell consists mostly of carbon-based molecules. • Organic chemistry is the study of carbon compounds. Carbon Chemistry • Carbon is a versatile atom. • It has four electrons in an outer shell that holds eight. • Carbon can share its electrons with other atoms to form up to four covalent bonds. • Carbon-Carbon bonds are strong and can therefore serve as the backbone to many organic molecules • Carbon can use its bonds to: • Attach to other carbons. • Form an endless diversity of carbon skeletons. Figure 3.2 • The simplest organic compounds are hydrocarbons. • These are organic molecules containing only carbon and hydrogen atoms. • The simplest hydrocarbon is methane. Figure 3.3 • Larger hydrocarbons • Are the main molecules in the gasoline we burn in our cars. • The hydrocarbons of fat molecules provide energy for our bodies. Quick Check – Hands Up! Which of the following is not a property of carbon? • A. Carbon-to-carbon bonds are limited to single bonds. • B. Carbon has four valence electrons. • C. Carbon can form bonds to various other atoms. • D. Two carbon atoms can share three electron pairs with each other. • E. Carbon-to-carbon bonds are strong. Quick Check – Hands Up! What aspect of long carbon chains makes them ideal for forming the backbones of long biomolecules? a. The carbon atom itself is strong and hard to split. b. Carbon can form a maximum of five covalent bonds with other atoms. c. Carbons can form a maximum of three covalent bonds with other atoms. d. Carbon-to-carbon covalent bonds are strong. e.Carbon-to-carbon hydrogen bonds are weak and transitory. Quick Check! How many electrons pairs are shared between carbon 2 and carbon 3 in this picture? Figure 3.4 • Each type of organic molecule has a unique threedimensional shape that defines its function in an organism. • The molecules of your body recognize one another based on their shapes. • The unique properties of an organic compound depend not only on its carbon skeleton but also on the atoms attached to the skeleton. • These atoms are called functional groups. Figure 3.5 Giant Molecules from Smaller Building Blocks • On a molecular scale, many of life’s molecules are gigantic. • Biologists call them macromolecules. • Examples: DNA, carbohydrates • Most macromolecules are polymers. • Polymers are made by stringing together many smaller molecules called monomers. • Cells link monomers by dehydration reactions. Figure 3.6a Figure 3.10 • Organisms also have to break down macromolecules. • Cells do this by a process called hydrolysis. Figure 3.6b Biological Molecules • There are four categories of large molecules in cells: • Carbohydrates • Lipids • Proteins • Nucleic acids Introduction • Cells join smaller organic molecules together to form larger molecules. • The four major classes of macromolecules are: carbohydrates, lipids, proteins, and nucleic acids. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings 1. Most macromolecules are polymers • Three of the four classes of macromolecules form chainlike molecules called polymers. • Polymers consist of many similar or identical building blocks linked by covalent bonds. • The repeated units are small molecules called monomers. • Some monomers have other functions of their own. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings • The chemical mechanisms that cells use to make and break polymers are similar for all classes of macromolecules. • Monomers are connected by covalent bonds via a condensation reaction or dehydration reaction. • One monomer provides a hydroxyl group and the other provides a hydrogen and together these form water. • This process requires energy and is aided by enzymes. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 5.2a • The covalent bonds connecting monomers in a polymer are disassembled by hydrolysis. • In hydrolysis as the covalent bond is broken a hydrogen atom and hydroxyl group from a split water molecule attaches where the covalent bond used to be. • Hydrolysis reactions dominate the digestive process, guided by specific enzymes. Fig. 5.2b Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Quick Check – Hands Up Refer to Figure 03-1. The process illustrated in the figure is called: a. condensation. b. protein synthesis. c. hydrolysis. d. dehydration synthesis. e. denaturation Quick Check – Hands Up Which of the following illustrates hydrolysis? a. the reaction of two monosaccharides to form a disaccharide b. the reaction of two amino acids to form a dipeptide c. the reaction of a hydrogen atom and a hydroxide ion to form water d. the reaction of a fat to form glycerol and fatty acids e. the formation of ATP from ADP and inorganic phosphate Pair Share • Outline how monosaccharides are converted into polysaccharides.