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AP Biology

Lipids: Fats & Oils

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AP Biology 2006-2007

Lipidslong term energy storage

concentrated energy

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AP Biology

Lipids

Lipids are composed of C, H, O

long hydrocarbon chains (H-C)

Family groups

fats

phospholipids

steroids

Do not form polymers big molecules made of smaller subunits

not a continuing chain

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AP Biology

Fats

Structure:

glycerol (3C alcohol) + fatty acid

fatty acid =

long HC tail with carboxyl (COOH) group head

dehydration synthesis

H2O

enzyme

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AP Biology

Building Fats

Triacylglycerol

3 fatty acids linked to glycerol

ester linkage = between OH & COOH

hydroxyl carboxyl

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AP Biology

Dehydration synthesis

dehydration synthesis

H2O

H2O

H2O

H O

enzyme

enzyme

enzyme

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AP Biology

Fats store energy

Long HC chain

polar or non-polar?

hydrophilic or hydrophobic?

Function:

energy storage

concentrated

all H-C!

2x carbohydrates

cushion organs

insulates body

think whale blubber!

Why do humans

like fatty foods?

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AP Biology

Saturated fats

All C bonded to H

No C=C double bonds

long, straight chain

most animal fats

solid at room temp.

contributes to

cardiovascular disease

(atherosclerosis)

= plaque deposits

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AP Biology

Unsaturated fats

C=C double bonds inthe fatty acids

plant & fish fats

vegetable oils liquid at room temperature

the kinks made by double

bonded C prevent the

molecules from packingtightly together

mono-unsaturated?

poly-unsaturated?

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AP Biology

Trans fats are a type of isomer

Fatty acid tails are hydrocarbons.Unsaturated fats have double bonds

between carbons.

Form follows function!

Trans fats are straight and solidify at

room temperature.

Cis (olive oil)

Trans (partially hydrogenated

vegetable oil)

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AP Biology

Phospholipids

Structure:

glycerol + 2 fatty acids + PO4 PO4 = negatively charged

Its just like apenguin

A head at one end& a tail

at the other!

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AP Biology

Phospholipids

Hydrophobic or hydrophilic?

fatty acid tails =

PO4 head =

split personality

interaction with H2O

is complex & very

important!repelled by water

attracted to water

Come here,No, go away!Come here,

No, go away!

hydrophobic

hydrophillic

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AP Biology

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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AP Biology

Why is this important?

Phospholipids create a barrier in water

define outside vs. inside

they make cell membranes!

Tell themabout soap!

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AP Biology

Steroids

Structure:

4 fused C rings + ??

different steroids created by attaching different

functional groups to rings different structure creates different function

examples: cholesterol, sex hormones

cholesterol

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AP Biology

Cholesterol

Important cell component

animal cell membranes

precursor of all other steroids

including vertebrate sex hormones

high levels in blood may contribute to

cardiovascular disease

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AP Biology

Cholesterol

helps keep

cell membranes

fluid & flexible

Important component of cell membrane

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AP Biology

From Cholesterolp Sex Hormones

What a big difference a few atoms can make!

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AP Biology

Any Questions?

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AP Biology 2006-2007

Lets build some

Lipids!

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AP Biology 2007-2008

Ghosts of Lectures Past(storage)

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AP Biology

Phospholipids & cells

Phospholipids of cell membrane double layer = bilayer

hydrophilic heads on outside in contact with aqueous solution outside of

cell and inside of cell hydrophobic tails on inside

form core

forms barrier between cell &external environment

Tell themabout soap!