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Exam Review - Chapter 19

Interact with water o reduce the hydrophobic surface

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Unformatted text preview: ipids with biosynthetic pathways secondary metabolites: compounds that are not central to an organisms’ metabolism but serve some subsidiary function 10.4 –Working with Lipids complex mixtures of lipids are separated by differences in polarity or solubility in nonpolar solvents lipids that contain ester- or amide- linked fatty acids can be hydrolyzed by treatment with acid or alkali lipids can be extracted through organic solvents, that prevent lipid clustering mass spectrometry can reveal lipid structure o can establish the length of the hydrocarbon chain or position of double bonds Chapter 11: Biological Membranes and Transport Membranes define the external boundaries of cells and control the molecular traffic across the boundary Membranes are selectively permeable to polar solutes o Flexible to accompany cell growth and movement o – The Composition and Architecture of Membranes contains proteins and polar lipids as well as carbohydrates Proportions of lipid and protein vary with the type of membrane, diversity of roles Membranes are impermeable to most polar or charged solutes, but permeable to nonpolar compounds Fluid mosaic model: phospholipids form a bilayer in which the nonpolar regions of the lipid molecules in each layer face the core of the bilayer and their polar head groups face outward Proteins are embedded in this bilayer sheet Some proteins protrude from only one side Have functional asymmetry caused by uneven distribution of proteins Membrane is fluid because most of the interactions are noncovalent Glycerophospholipids, sphingolipids, and sterols are insoluble in water o Form lipid aggregates and clusters in water with hydrophobic moieties in contact and hydrophilic regions interact with water o Reduce the hydrophobic surface area exposed to water and minimizes the number of molecules in the ordered shell of water increase in entropy 3 types of lipid aggregates can form: Micelles: spherical structures that contain anywhere from a few dozen to a few thousand amphipathic molecules o Favored when the cross- sectional area of the head group is greater than thatof the acyl side chain Bilayer: lipid aggregate in which two lipid monolayers form a two- dimensional sheet o Favored if the cross- s...
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