Definition: Lipids are biomolecules that contain fatty acids or a steroid nucleus, soluble in organic solvents but insoluble in water.
Originates from Greek word "lipos" meaning fat.
Play a crucial role in cell membranes, fat-soluble vitamins, and steroid hormones.
Lipids are organic compounds that are not soluble in water, emphasizing their hydrophobic nature.
Definition: Long, unbranched carbon chains with a carboxylic acid group at the end.
Length: Typically contain 12-18 carbon atoms.
Insolubility: Long carbon chain makes them insoluble in water.
Types:
Saturated: No C=C double bonds present.
Unsaturated: Contains C=C double bonds.
In skeletal formulas, ends and bends of lines represent carbon atoms.
Example: Lauric acid can be depicted in various structural forms.
Saturated Fatty Acids: Only single C—C bonds present, generally solid at room temperature with higher melting points.
Monounsaturated Fatty Acids: Contain one C=C double bond.
Example: Oleic acid found in olives.
Polyunsaturated Fatty Acids: Contain at least two C=C double bonds.
Unsaturated fatty acids have two isomeric forms: cis and trans.
Most naturally occurring unsaturated fatty acids are cis isomers and are oils at room temperature.
Saturated fatty acids fit closely together due to regular pattern, enduring higher melting points and remaining solid at room temperature.
Unsaturated fats (from vegetable oils and fish) are healthier than saturated fats.
Omega-6 fatty acids, like linoleic and arachidonic acids, initiate their first double bond at the sixth carbon from the methyl end.
Waxes are long-chain fatty acid esters with alcohols.
Structure: Composed of 14-30 carbon atoms.
Function: Serve as protective coatings to prevent water loss in plants.
Examples:
Beeswax and Carnauba wax (Brazilian palm tree).
Definition: Esters of glycerol (a trihydroxy alcohol) and fatty acids formed by dehydration reaction.
Generally, three hydroxyl groups in glycerol react with three fatty acids.
Names are derived by changing "glycerol" to "glyceryl."
Example: Glyceryl tristearate is the compound formed from three stearic acids, commonly known as tristearin.
Can contain different fatty acids (e.g., stearic, oleic, and palmitic acids).
Process where unsaturated fats are converted into saturated fats, potentially forming trans fats, which can be unhealthy.
Hydrolysis breaks down triacylglycerols into glycerol and three fatty acids, requiring strong acids (HCl or H2SO4) or enzymes (lipases).
Definition: Reaction of fats with strong bases like NaOH in heat, yielding glycerol and sodium salts of fatty acids (soaps).
Produces solid soaps with NaOH and softer liquid soaps with KOH.