rav65819_ch03_033-058

rav65819_ch03_033-058 - *32 3 The Chemical Building Blocks...

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***32 3 The Chemical Building Blocks of Life introduction A CUP OF WATER CONTAINS more molecules than there are stars in the sky. But many molecules are much larger than water molecules; they consist of thousands of atoms, forming hundreds of molecules that are linked together into long chains. These enormous assemblies, which are almost always synthesized by living things, are macromolecules. As you may know, biological macromolecules can be divided into four categories: carbohydrates, nucleic acids, proteins, and lipids, and they are the basic chemical building blocks from which all organisms are assembled. Biological macromolecules all involve carbon-containing compounds, so we begin the discussion with a brief summary of carbon and its chemistry. The study of the chemistry of carbon, because of its biological significance, is known as organic chemistry. n RNA is a transcript of a DNA strand n Other nucleotides are vital components of energy reactions 3.4 Proteins: Molecules with Diverse Structures and Functions n Proteins are polymers of amino acids n Proteins have levels of structure n Motifs and domains are additional structural characteristics n The process of folding relies on chaperone proteins n Some diseases may result from improper folding n Denaturation inactivates proteins 3.5 Lipids: Hydrophobic Molecules n Fats consist of complex polymers of fatty acids attached to glycerol n Fats are excellent energy-storage molecules n Phospholipids form membranes 33
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concept outline 3.1 Carbon: The Framework of Biological Molecules n Functional groups account for differences in molecular properties n Isomers have the same molecular formulas but different structures n Biological macromolecules include carbohydrates, nucleic acids, proteins, and lipids 3.2 Carbohydrates: Energy Storage and Structural Molecules n Monosaccharides are simple sugars n Sugar isomers have functional differences n Disaccharides serve as transport molecules in plants and provide nutrition in animals n Polysaccharides provide energy storage and structural components 3.3 Nucleic Acids: Information Molecules n Nucleic acids are nucleotide polymers n DNA carries the genetic code ***33 3.1 Carbon: The Framework of Biological Molecules S H CH 2 carbohydrates, proteins, nucleic acids, lipids carbohydrates, nucleic acids In chapter 2, we reviewed the basics of chemistry. No new laws of chemistry are found in biological systems, and biological systems do not violate the laws of chemistry. Thus, chemistry forms the basis of living systems. The framework of biological molecules consists predominantly of carbon atoms bonded to other carbon atoms or to atoms of oxygen, nitrogen, sulfur, or hydrogen. Because carbon atoms can form up to four covalent bonds, molecules containing carbon can form straight chains, branches, or even rings, balls, and coils. Molecules consisting only of carbon and hydrogen are called
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This note was uploaded on 10/15/2010 for the course BIO BIO1 taught by Professor Lipke during the Fall '09 term at CUNY Brooklyn.

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rav65819_ch03_033-058 - *32 3 The Chemical Building Blocks...

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