LS2_Ch3Outline - Chapter 3: Macromolecules and the Origin...

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Chapter 3: Macromolecules and the Origin of Life Macromolecules: carbohydrates, proteins, lipids, and nucleic acids. - Large—molecular weights range from hundreds of Daltons (sucrose) to billions (nucleic acids). - All contain carbon atoms organic molecules . - Held together largely by covalent bonds that give them important structural stability and form the basis of some of their functions. - All unique to the living world. 3.1: What kinds of molecules characterize living things? Biological molecules that are characteristic of living things: proteins, carbohydrates, lipids, and nucleic acids. - Most are large polymers (“many unit”) constructed by covalent bonding of monomers (smaller molecules, ones that make up each biological molecule have similar chemical structures). - Macromolecules: polymers with molecular weights >1,000 Da. - How these molecules interact with other molecules depends on properties of functional groups in their monomers. I. Functional groups give specific properties to molecules A. Functional groups: certain small groups of atoms consistently found together in different biological molecules. 1. Each has specific chemical properties, and confers those properties onto an attached larger molecule. 2. Hydroxyl group : polar, attracts water molecules. Containing molecules usually dissolve easily in water. 3. Keto group : oxygen is highly electronegative and can attract hydrogen of another electronegative atom (eg. Nitrogen) to form a hydrogen bond. II. Isomers have different arrangements of the same atoms A. Isomers: molecules with same chemical formula, but atoms are arranged differently. 1. Structural isomers: differ in how atoms are joined together. Each has different chemical properties. 2. Optical isomers: two resulting mirror images of an asymmetrical carbon (carbon with four different atoms or groups attached) (eg. Hands, gloves) a. Some biochemical molecules that can interact with one optical isomer of a carbon compound are unable to fit the other. III. The structures of macromolecules reflect their functions A. Biological macromolecules are present in ~ the same proportions in all living organisms. B. Biochemical unity : function of a protein in one organism having a similar function in another. Allows organisms to acquire food by eating other organisms. C. Macromolecules perform some combination of functions such as: energy storage, structural support, protection, catalysis, transport, defense regulation, movement, and information storage. 1. Roles not exclusive—both carbs an proteins play structural roles, protecting tissues and organs. 2. Only nucleic acids specialize in information storage for hereditary material. D.
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This note was uploaded on 05/07/2008 for the course LIFESCI 2 taught by Professor Pires during the Spring '08 term at UCLA.

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LS2_Ch3Outline - Chapter 3: Macromolecules and the Origin...

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