2006-2007 AP Biology

Lipids

OilsFats

AP Biology

Lipids: Fats & Oils

AP Biology

Lipids Lipids are composed of C, H, O

Not considered polymers-no subunits

“Family groups” Fats Phospholipids Steroids

Polymers big molecules made of smaller subunits not a continuing chain

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Fats Structure:

Glycerol and fatty acids fatty acid =

long HC “tail” with carboxyl (COOH) group “head”

dehydration synthesis

H2Oenzyme

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Building Fats Triacylglycerol

3 fatty acids linked to glycerol Ester linkage = between OH & COOH

hydroxyl carboxyl

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Dehydration synthesis

H2O

H2O

H2O

H2O

enzyme

enzyme

enzyme

dehydration synthesis

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Fats store energy Long HC chain

polar or non-polar? hydrophilic or hydrophobic?

Function: Store Energy

concentrated all H-C!

2x carbohydrates Cushioning Insulates

think whale blubber!

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Saturated fats All C bonded to H No C=C double bonds

Solid at Room Temp. Butter Lard

contributes to cardiovascular disease (atherosclerosis) = plaque deposits

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Unsaturated fats C=C double bonds in

the fatty acids One or more double bonds Plant Fats Liquid at Room Temp.

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

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Saturated vs. unsaturated_______________ _______________

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Phospholipids Structure:

glycerol + 2 fatty acids + PO4

PO4 negatively charged

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Phospholipids Hydrophobic or hydrophilic?

fatty acid tails = Hydrophobic PO4 head = Hydrophilic split “personality”

interaction with H2O is complex & very important! “repelled by water”

“attracted to water”

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Phospholipids in water Tails repelled by water Heads attracted to water

can self-assemble into “bubbles” bubble = “micelle” can also form a 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 Membrane

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Steroids Structure:

4 fused C rings + ?? different steroids created by attaching different

functional groups to rings different structure creates different function

What are some examples:

cholesterol

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Cholesterol Important cell component

Part of the cell membrane Used to make other types of 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

AP Biology

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

2006-2007 AP Biology

Let’s build some

Lipids!