L36L37_lipidmem_462A_2013sm

Describe the permeability properties of lipid

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Unformatted text preview: Discuss how living organisms regulate the fluidity of their membranes, including in your discussion the effects on fluidity of temperature, fattyacyl chain length, and number of double bonds. •  Describe the permeability properties of lipid bilayers. •  Discuss the concepts of lateral and transverse (“flip-flop”) diffusion of membrane lipids and the asymmetric distribution of membrane components on the extracellular and intracellular sides of the bilayer. Biochemistry happens in cells that are enclosed by membranes. •  The boundaries of cells and eukaryoFc organelles (mitochondria, chloroplasts ….) are defined by membranes. •  Membranes have two main components: lipids and proteins. –  Both can be covalently linked to carbohydrates. •  Membranes are selecFvely permeable: specific substances can cross membranes in a controlled manner. •  Membranes allow different organelle to have different chemical environments (e.g. pH, salt concentraFon, etc) Lipids come in many shapes and sizes and perform a variety of funcFons in cells What do all of these molecules have in common? Lipids come in many shapes and sizes and perform a variety of funcFons in cells Hydrophilic head group Hydrophobic faXy acyl chain Hydrophilic head group Hydrophobic faXy acyl chain What do all of these molecules have in common? Saturated FaXy Acids pKas of 4 ­5 Length of chain varies Carboxyl group covalently linked to a hydrocarbon chain Unsaturated FaXy Acids pKas of 4 ­5 Length of chain varies usually cis conformaFon •  Monounsaturated faXy acids have one C=C double bond •  Polyunsaturated faXy acids have mulFple C=C double bond Monosaturated (18:1) , Oleic acid Saturated faXy acids pack more Fghtly than unsaturated faXy acids Trans FaXy Acid cis trans •  FaXy acids found in nature are usually in the cis conformaFon •  Increasing evidence implicate trans fa...
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This test prep was uploaded on 02/25/2014 for the course BIOC 462A taught by Professor Ziegler,baldwin during the Spring '08 term at University of Arizona- Tucson.

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