Repot Lipids

8/13/2019 Repot Lipids

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Alyssa M. Ong


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Greek ~ lipos ~ fat

Lipids are a large and

varied group of organic

compounds.

They are insoluble in water

but will dissolve in organic


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Composed of Carbon,Hydrogen, and Oxygen

Greater than 2:1 ratio ofH:O found in carbohydrates

Building blocks are fatty

acids and glycerol.


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Source of energy

Building blocks ofmembranes


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Lipids tend to dissolve readily

in organic solvents, such asether and chloroform, rather

than in highly polar solventssuch as water. This property

sets them apart from

biological substances such as

carbohydrates and proteins.


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Triglycerides (Fats and

Oil)Phospholipids

Steroids

Waxes


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Most common type of

lipid.3 fatty acids and a

glycerol molecule arelinked by an ester bond

formed during


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-SATURATED FATS: all available bondsare occupied by hydrogen

Most animal fats are saturated e.g.bu tter, lard

-UNSATURATED FATS: contain C-C

double bonds in the molecule.

Oils tend to be more available in plants

e.g. sunf low er oi l , ol ive oi l


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Saturated fatty acids do not have a

double bond between the carbon

atoms. Saturated fatty acids have a higher

melting points and are solid at room

temperature.

Animal fats are classified as a

saturated fatty acid.


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Unsaturated fatty acids have doublebonds between some of the carbon

atoms

Unsaturated fatty acids have a low

melting point and may be liquid at

room temperature. Plant oils are an example of an

unsaturated triglyceride


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The hydrolysis of oils or fats

by boiling with an aqueoussolution of an alkali-metal

hydroxide is calledSAPONIFICATION.

Saponification is the process

used to make soap. Soaps

are thus the alkali metal (Na,

K or Li salts of fatt acids.


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Same as triglycerides except

one of the fatty acids

molecules is replaced by aphosphate group.

The phosphate group is polarand so is attracted to water

therefore the phospholipid has


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A hydrophilic head (water-loving) thatdissolves in water and a

Hydrophobic tail (water-hating) that isrepelled by water.

This property causes phospholipidsto spontaneously form lipid bilayers.


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The lipid bilayer of a

cell membrane is abarrier against the

passage of molecules

and ions into and outof the cell.


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Proteins, such as enzymes, may be

bound to the interior surface of the

membrane. Many membrane

proteins have attached carbohydrate

molecules. The carbohydrate portionis on the exterior of the lipid bilayer,

where it can hydrogen-bond with

water. The protein portion is on theinterior of the lipid bilayer, so it does

not contact the water.


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Lipids often found in cell membrane (example,

cholesterol)

Very different structure- 4 carbon rings with variety

of different side chains


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Cholesterol can be converted in body to

vitamin D and bile salts (used to digest fats)

Estrogen, testosterone, and progesterone aresteroid sex hormones


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Waxes are also part of the lipid

family. Waxes are esters of

long-chain fatty acids and long-chain alcohols. The

hydrocarbon chains for both theacid and the alcohol usually

contain from 10 to 30 carbon


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Lipids with long fatty acid chains linked to alcohol or

carbon rings.


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Waxes are low melting, stable

solids that occur in both plants

and animals. In plants, a wax

coat protects the surfaces of

leaves from water loss and attackby microorganisms. For example,

carnauba wax, a major ingredientin car wax and floor polish, is

found on the leaves of a South

American Palm Tree.


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Waxes are widely distributed innature. The leaves and fruits of

many plants have waxy coatings,which may protect them from

dehydration and small predators.The feathers of birds and the furof some animals have similar

coatings which serve as a waterrepellent. Carnuba wax is valuedfor its toughness and water

resistance.


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Thank you.God Bless!

Repot Lipids

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