AP Biology

Lipids

energy storage

AP Biology

Lipids Lipids are composed of C, H, O

long hydrocarbon chain 4 types of lipids

fatsphospholipidssteroidswaxes

fat

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1. TriglyceridesFat molecules

3 fatty acids chains linked to glycerol

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Fats store energyLong HC chain

Hydrophobic“water – fearing” = insoluble in water

Function:energy storage

very rich2x carbohydrates

cushion organsinsulates body

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Saturated fatsAll C bonded to HNo C=C double bonds

long, straight chainmost animal fats solid at room temp.

contributes to cardiovascular disease (atherosclerosis) = plaque deposits

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Unsaturated fatsAt least one C=C double bond in

the fatty acidsplant & fish fats vegetable oilsliquid at room temperature

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

mono-unsaturated?poly-unsaturated?

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Saturated vs. unsaturatedsaturated unsaturated

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2. Phospholipids Structure:

glycerol + 2 fatty acids chains + phosphate headPO4 negatively charged

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PhospholipidsHydrophobic or hydrophilic?

fatty acid tails = hydrophobicPO4 = hydrophilic headdual “personality”

interaction with H2O is complex & very important!

It likes water & also pushes

it away!

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Phospholipids in waterHydrophilic heads attracted to H2O

Hydrophobic tails “hide” from H2Ocan self-assemble into “bubbles” can also form a phospholipid bilayer

Found in animal cells (cell membrane)

bilayer

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Steroidsex: cholesterol, sex hormones4 fused C rings

different steroids created by attaching different functional groups to rings

cholesterol

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CholesterolImportant cell component

animal cell membranesprecursor of all other steroids

including vertebrate sex hormoneshigh 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 HormonesWhat a big difference a few atoms can make!

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What is the function of a triglyceride?

1 2 3 4

0%5%

0%

95%1. Stores and transfers genetic information

2. Stores energy3. Control the rate

of reactions4. Help to fight

disease

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Fats that have at least one double bond between Carbon atoms are called

1 2 3 4

88%

6%0%

6%

1. Unsaturated2. Saturated3. Glycerol4. Fatty Acids

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What is another name for a fat molecule?

1 2 3 4

15%

75%

0%

10%

1. phospholipid2. Cholesterol3. Steroid4. triglyceride

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Phospholipids have a

1 2

95%

5%

1. hydrophobic head and hydrophilic tail

2. hydrophilic head and hydrophobic tail

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Which of the following is an example of a steroid

1 2 3 4

0% 0%0%

100%1. Fatty acids2. Sex Hormones3. Phospholipids4. Olive Oil