lipids

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what are lipids

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1. 1. lipids are a loosley defined group of moleculeus wiht one main characteristic : insolcuble in water but soluble in organic solvents like chloroform

2. 2. lipids consist of carbon, hydrogen, oxygen but OXYGEN RATIO IS MUCH LESS THATN HYDROGEN

3. 3. fats are lipids that are at solid state at 20 degrees and oils are lipids that are at liquid state at 20 degrees

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types of lipids

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1. 1. simple lipids are made up of fatty acids and various alcohols, Fats are esters of fatty acids and glycerol and waxes are esters of fatty acids and complex molecules

2. 2. compounds lipids : non lipid components + lipid eg phospholipid : phosphate + lipid made of fatty acids and alcohol like glycerol

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components of fats

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fats (simple lipids) composed of fatty acids and glycerol

1. 1. glycerol is an alcohol with three carbons each bearing a hydroxyl group

2. 2. fatty acids consist of a hydrocarbon chain and a carboxyl group (-cooh)

3. - a hydorcrarbon chain constis of a chain of carbon atoms to which hydrogen atoms are attatched, ususally even numbered chains of 14-20 carbons

4. - can be saturated or unsaturated

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types of fatty acids

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1. 1. satruated fatty acids : general formula of RCOOH where r is the hydorcabron chain made up entirely of single c-h and c-c bonds

2. - the hydrocarbon chain does not contain ANY carbon carbon double bonds and contains the max number of hydrogen bonds

3. - saturated fatty acids = saturated fats

4. - a fat high in saturated fatty acids are more solid at room temperature thn fats with unsaturated fatty acids.

5. - all animal fats except fish oil are saturated

6. 2. unsaturated fatty acids in which the hydrocarbon chain contains carbon carbon double bonds and the presence of double bonds causes kinks in the hydrocarbon chain and if there is more than one carbon carbon double bond, then it is polyunsaturated

7. -unsartuated fatty acids = unsaturated fats

8. - fats with higher content of polyunsaturated fatty acids have low melting points because their fatty acid chains bend at the double bonds, preventing fat molecules from aligning closely with one another, hence usually liquid at room temperature like corn and olive oil

9. - most plant fats except palm and coconut are unsaturated

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reaction for synthesis of lipids

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1. 1. a typical simple lipid in human body is triglyceride.

2. 2. one molecule of triglyceride includes three fatty acid molecules and one glycerol moelcule

3. 3.. each hdyroxyl group of the glycerol molcule reacts with the carboxyl group of the fatty acid. in this reaction an ESTER bodn is formed between the glycerol molecule and one fatty acid and one molcule of water is removed. this is a condensation reaction

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function of lipids

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1. 1. triglycerides serves as form of storage for energy, they are higher energy value than starch or glycogen and harder to hydrolyse completely than starch or hydrogen --> good long term storage

2. 2. good thermal insulators to prevent excessive heat loss

3. 3. to protect delicate organs by lining ext of delicate organs to reduce damage from mechanical shock

4. 4. major component of cell membrane

5. 5: releases metabolic water when hydrolysed

6. 6: improves buoyancy of object since its low density

7. 7: electrical insulator

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test for lipid

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1. 1. ethanol emulsion test,

2. 2: principle : lipids readily soluble in organic solvents like ethanol but not in water and from emulsions on vigourous shaking

3. 3: method:

4. 1. add 2 cm3 of ethanol to two drops of test substance (grind if solid and let solid particles settle ) in a test tube and mix well

5. 2: decant ethanol into another test tube containting 2 cm3 of water and mix well and observe for cloudiness

-ve result: homogenous or clear solution formed with ethanol and solution remains homogenous when water was added

+ve result : homogenous or clear solution formed with ethanol BUT white emulsion formed when water was added