Bite-Sized Morsels of Biology that are Good and Good For You
Lipids
Lipids are non-polar molecules such as fats, oils, and waxes that serve many different functions in living things.
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They are made of C, H, and O
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They are made of glycerol and fatty acids, but have no true repeating monomers.
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They store long term energy
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They serve as a barrier keeping certain substances out, and others in
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Some are used as hormones or other chemical messengers
Lipids Store Energy
Lipids are used to store energy for long periods of time - days to weeks to years, maybe even a lifetime.
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Lipids provide 9 calories per gram (carbs and proteins only provide 4 cal/g)
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Glycerol can be used in glycolysis; fatty acid chains can be broken down in the Krebs Cycle
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Plants typically use oils (liquids at room temperature) whereas many animals use fat (solid at room temperature).
Lipids as Barriers
Lipids are non-polar, so substances dissolved in water have a hard time passing through structures made of lipids.
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Cell membranes are made of a phospholipid bilayer
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Fruits and leaves are surrounded by a thin layer of wax to hold water in and prevent them from drying out
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Many animals are surrounded by a layer of blubber (fat) that serves as a temperature barrier - it keeps heat in near the vital organs even in very cold weather
