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Unformatted text preview: LECTURE 4. 31 August 2009 (P. J. Hollenbeck) BIOL 231 STRUCTURES OF BIOLOGICAL MACROMOLECULES Read: Chap 2: pp. 50-61; Panels 2-3 thru 2-6; DVD 2.1-2.3; Problem assignment: 11-13 <be sure to download from the web syllabus the set of extra figures that accompany this lecture> I. Questions and classes (A) What we want to know about the macromolecules that make up the cell (1) There are 4 major classes of macromolecules in the cell that we will consider repeatedly through out this course. They have the common chemical composition of : C, H, O, N, P, S. They are synthesized from smaller, building block molecules which allows efficient recycling and turnover of the macromolecules in the cell. But they are otherwise very different. (2) Take the opportunity now to re-familiarize yourself with each of these 4 groups of macromolecules. As you study them, ask yourself: What are the properties of each? Which of the seven functional groups do they contain? What building blocks comprise them, and how are they constructed? Do they form larger polymers or other associations? Where are they found in the cell, and what are their functions? (B) 4 classes of macromolecules (1) Lipids we will consider steroids and phospholipids, which between them constitute the bulk of the plasma and organelle membranes. (2) Carbohydrates monosaccharides (e.g., glucose, ribose, etc), which are building blocks for oligosaccharides (e.g., the carbohydrate chains attached to membrane proteins), and polysaccharides (e.g., cellulose, glycogen, starch) (3) Nucleic acids nucleotides are building blocks for DNA and RNA, as well as energy substrates and phosphate sources for a multitude of cellular reactions. (4) Proteins amino acids are the building blocks of polypeptides (protein molecules) II. Structure and function (A) Lipids (1) Lipids in the cell come in 2 general flavors those with acyl chains and those with carbon ring backbones. (2) Those with ring backbones are steroids such as cholesterol (see fig below ), which shares a 4-ring structure with other steroids but has substituent groups that are unique. The ring structure is rigid and planar. The OH group confers some polar character. (3) Lipids with acyl chains include triglycerides and phospholipids (see extra figures )....
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- Fall '08