Lecture 2

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Unformatted text preview: byl • Steroid 3(6member)rings,1(5member) Image: phospholipids Note the kink caused by the unsaturated bond (double bond). Lipid types Fatty acids • Importance of unsaturated (double bond). It can have two forms: cis and trans • Cis = on same side, trans = across • -7- • cis and trans forms of the same fatty acid chain. Note that the trans bond eliminates the kink • A realistic picture of oleic acid (see Syllabus>Useful web material>3D Chem Ring-lipids • Steroids: 3(6-member)rings+1(5-member). Membrane component. • Cholesterol Membranes Phosphate Lets formally introduce a very important molecule: Phosphoric acid, PO3H3, it ionizes to phophate ion, PO3H2- + H+ Phospholipids Lipids are both storage and structural molecules. The most important structural function is the formation of membranes: the envelopes that forms cellular compartments. We will cover more of the membrane in a future lecture. Here it is important to understand that membrane lipids have special properties: a charged head and a hydrophobic tail. This is exemplified by a typical phospho-lipid, which consists of the following: 1. Two fatty acids linked (esterified) to glycerol -8- 2. A glycerol backbone made of three carbons, two attached to the fatty acids 3. A phosphate (negatively charged )linked to glycerol 4. A positively charged molecule (choline) linked to phosphate The phospholipid is strongly charged on the head (3+4) and hydrophobic on the tail (1). When in water, phospholipids aggregate to position the fatty acid tails side by side, and the polar heads into contact with water Different types of aggregates formed by P-lipids. -9-...
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This note was uploaded on 02/19/2014 for the course BIS 2A taught by Professor Grossberg during the Spring '08 term at UC Davis.

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