CHAPTER 4CHAPTER 4CHEMICAL CHEMICAL

COMPOSITIONOF THE CELLCOMPOSITIONOF THE CELL

4.4 LIPIDS4.4 LIPIDS

Energy rich organic compounds made of :Energy rich organic compounds made of : 1) carbon 1) carbon 2) hydrogen2) hydrogen 3) oxygen3) oxygen

The percentage of oxygen in lipids is lower The percentage of oxygen in lipids is lower than in carbohydrate.than in carbohydrate.

Some lipids contain nitrogen and phosphorus.Some lipids contain nitrogen and phosphorus.

As lipids are non-polar molecules, they are As lipids are non-polar molecules, they are insoluble in water but dissolve readily in other insoluble in water but dissolve readily in other lipids and in non-polar solvents such as ether lipids and in non-polar solvents such as ether and ethanol.and ethanol.

Fats and oils (triglycerides)Fats and oils (triglycerides)WaxesWaxesPhospholipidsPhospholipidsSteroids Steroids

Store large amounts of energy for long Store large amounts of energy for long terms.terms.

Act as sources of energy.Act as sources of energy.Form a major part of the structure of cell Form a major part of the structure of cell

membranes.membranes.Act as a metabolic source of water.Act as a metabolic source of water.Reduce the lost of water by evaporation.Reduce the lost of water by evaporation.

Fats are solid at room temperature while oils are Fats are solid at room temperature while oils are liquid.liquid.

Fats and oils are triglycerides.Fats and oils are triglycerides. Triglycerides is formed from a condensation Triglycerides is formed from a condensation

reaction between one molecules of glycerol and reaction between one molecules of glycerol and three molecules of fatty acids. The bonds formed three molecules of fatty acids. The bonds formed are called ester bonds. Three molecules of water are called ester bonds. Three molecules of water are removed in this reaction. are removed in this reaction.

Fats often contain only saturated fatty acids Fats often contain only saturated fatty acids while oils usually contain unsaturated fatty acids.while oils usually contain unsaturated fatty acids.

Glycerol triglycerides Glycerol triglycerides

+ + condensation condensation ++

3 molecules of 3 molecules of3 molecules of 3 molecules of

Fatty acids Fatty acids hydrolysis hydrolysis waterwater

GLYCEROLGLYCEROL

Fatty acid Fatty acid fatty acid fatty acid

+ + condensationcondensation

Fatty acid GLYCEROL Fatty acid GLYCEROL fatty acidfatty acid

hydrolysis +hydrolysis +

Fatty acid Fatty acid fatty acidfatty acid 3H 3H22O O

COMPARING AND CONTRASTING SATURATED COMPARING AND CONTRASTING SATURATED FATS WITH UNSATURATED FATSFATS WITH UNSATURATED FATS

Both are triglycerides.Both are triglycerides.They yield 38kJ per They yield 38kJ per

gram.gram.Their molecules Their molecules

aggregate into globules aggregate into globules because of their because of their hydrophobic properties.hydrophobic properties.

SIMILARITIES

DIFFERENCESDIFFERENCESSATURATED SATURATED

FATSFATSTYPES OF FATSTYPES OF FATS UNSATURATED UNSATURATED

FATSFATS

absentabsent PRESENCE OF DOUBLE BONDS PRESENCE OF DOUBLE BONDS IN FATTY ACIDSIN FATTY ACIDS

presencepresence

unableunable ABILITY TO REACT WITH ABILITY TO REACT WITH ADDITIONAL HYDROGEN ADDITIONAL HYDROGEN

ATOMSATOMS

ableable

SolidSolid CONDITION AT ROOM CONDITION AT ROOM TEMPERATURETEMPERATURE

LiquidLiquid

higherhigher MELTING POINTMELTING POINT lowerlower

likelylikely CAUSE DISEASES OF THE CAUSE DISEASES OF THE HEART AND ARTERIESHEART AND ARTERIES

unlikelyunlikely

unlikelyunlikely BECOME RANCID DUE TO BECOME RANCID DUE TO OXIDATIONOXIDATION

likelylikely

Butter, animal Butter, animal fatsfats

EXAMPLESEXAMPLES Olive oil, corn Olive oil, corn oiloil

CREATE BY : ASMIDAR CREATE BY : ASMIDAR MOHD JAMILMOHD JAMIL

FARY_LURVIST 101’FARY_LURVIST 101’