AP Biology

Lipids: Fats & Oils

AP Biology

Lipids Lipids are composed of Carbon, Hydrogen, and

small amts of Oxygen long hydrocarbon chains (H-C)

Do not form polymers They are big molecules made of smaller subunits not a continuing chain

2006-2007 AP Biology

Lipid Functionslong term energy storage

InsulationWaterproofing

Hormone Production

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Fats Structure:

Fats, Oils and Waxes are made of a Glycerol molecule (3-Carbon alcohol) + fatty acid fatty acid =

long Hydrogen/Carbon “tail” with carboxyl (COOH) group head

dehydration synthesis

H2O

enzyme

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Building Fats Triacylglycerol

3 fatty acids linked to glycerol ester linkage = between OH & COOH…links a

glycerol to fatty acids. hydroxyl carboxyl

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Dehydration synthesis

dehydration synthesis

H2O

H2O

H2O

H2O

enzyme

enzyme

enzyme

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Fats store energy Long Fatty Acid Tail

It is non-polar Hydrophobic (repels water)

Function: energy storage

2x what is given in carbohydrates cushion organs insulates body

think whale blubber!

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Saturated fatty acids All Carbon bonded to Hydrogen No C=C double bonds

long, straight chain most animal fats solid at room temp.

contributes to cardiovascular disease = plaque deposits

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Unsaturated fatty acid tail C=C double bonds in the fatty acids

plant & fish fats vegetable oils liquid at room temperature

the kinks made by doublebonded Carbon prevent the molecules from packing tightly together

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Saturated vs. unsaturatedsaturated unsaturated

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Phospholipids Structure:

Made of a glycerol molecule + 2 fatty acids + PO4 (phosphate group) PO4 = negatively charged

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Phospholipids Hydrophobic or hydrophilic?

fatty acid tails = PO4 head = split “personality”

interaction with H2O is complex & very important!

“repelled by water”

“attracted to water”

hydrophobic

hydrophillic (attracted to water)

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Phospholipids in water Hydrophilic heads “attracted” to H2O

Hydrophobic tails “hide” from H2O can self-assemble into “bubbles”

bubble = “micelle” can also form a phospholipid bilayer early evolutionary stage of cell?

bilayer

water

water

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Why is this important? Phospholipids create a barrier in water

define outside vs. inside they make cell membranes!

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Steroids Structure:

4 fused Carbon rings + One Functional Grp?? different steroids created by attaching different

functional groups to rings Important: different structure = different function

examples: cholesterol, sex hormones

cholesterol

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Cholesterol- type of Steroid Important cell component

animal cell membranes

- keeps fatty acid tails from sticking together precursor of all other steroids

including vertebrate sex hormones high levels in blood may contribute to

cardiovascular disease

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Cholesterol

helps keep cell membranes

fluid & flexible

Important component of cell membrane

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From Cholesterol Sex Hormones What a big difference a few atoms can make!

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LIPIDS All Lipids are INSOLUBLE in water!