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BIO 118 Lec 6 lipids S.pptx

BIO 118 Lec 6 lipids S.pptx - Lipids Chapter 6 How did...

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Lipids Chapter 6
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How did lipids contribute to the development of life? Self replicating molecules, most likely RNA. As offspring were produced, natural selection favored those that reproduced ”better”. These descendants eventually developed a plasma membrane. Separates life from nonlife Serves as selective barrier Sequesters appropriate chemicals in an enclosed area which causes chemical reactions to happen more frequently.
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How do membranes form? Lipids are carbon-containing compounds that are nonpolar and hydrophobic. Isoprene-5-carbon compound can be found in linked chain called isoprenoid. o Pigments, vitamins, pre-curser to sex hormones. o Contain only carbon and hydrogen-hydrocarbon o Non polar because electrons are shared equally in C-H bonds.
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How does bond saturation affect hydrocarbon structure? Fatty acid-a lipid consisting of a hydrocarbon chain bonded to a carboxyl functional group. Typically contain 14-20 carbon atoms.
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How does bond saturation affect hydrocarbon structure? Saturated -hydrocarbon chains that consist of only single bonds between the carbons. Saturated with maximum number is hydrogen atoms that can attach to the carbon skeleton Unsaturated -hydrocarbon chains that have at least one double bond. Not saturated with hydrogen atoms because of the double bond- they can cause kinks in the chain (will relate to what the membrane will let in and out)
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How does bond saturation affect hydrocarbon structure? Highly saturated lipids (butter) have high melting points and are solid at room temperature. Saturated lipids that have long hydrocarbon tails (waxes) form stiff solids at room temperature. Unsaturated oils are liquid at room temperature. They may be converted to saturated lipids by breaking double bonds and adding hydrogen atoms.
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Types of lipids in cells Characterized by degree of insolubility in water. Insoluble-high proportion of nonpolar C-C and/or C-H bonds relative to polar nonfunctional groups. Steroids Fats Phospholipids
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Steroids Contain a bulky 4-ring structure. Differ from one another by the functional groups or side chains attached to different carbons in the hydrophobic rings. Estrogen, testosterone, cholesterol.
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Fats Nonpolar molecules composed of three fatty acids that are linked to a 3-carbon molecule called glycerol. Also called triglycerides. Energy storage.
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Phospholipids Glycerol linked to a phosphate group and two hydrocarbon chains of either isoprenoids or fatty acids. The phosphate group is also bonded to a small organic molecule that is charged. Crucial component of the cell membrane
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What do lipids do? Store energy. Act as pigments that capture or respond to sunlight.
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