Lipids
Dr. Joan Simam
Objectives
1. Definition and functions of lipids
2. Classification of lipids
3. Chemical properties of lipids
Definition:
o Lipids are organic compounds formed mainly from alcohol and fatty acids combined
together by ester linkage
o Very important biomolecules
o Insoluble in water
o Soluble in organic solvents and other lipids
o Lipids include fats, butter, ghee, lard, tallow, terpenes, steroids. Also vegetable oils such
as olive oil, corn oil, soybean oil, semsem oil, sun flower oil, cotton feed oil, fish oil
waxes and related compounds
FUNCTIONS OF LIPIDS
Storage molecules for ENERGY (fats and oils)
Structural components of cellular membranes
Protective molecules (waxes)
Hormones
Carrier of vitamins
Intracellular messengers
Pigments
Insulation
FOUR MAIN CLASSES OF LIPIDS
1. Triacylgylcerols (TAGs) – Storage Lipids (non-polar). Also known as triglycerides
2. Phosphoacylglycerols –Membrane Structural Lipids (polar)
3. Sphingolipids – Membrane Structural Lipids (polar)
4. Non-saponifiable Lipids – Steroids, hormones, cholesterol. Based on a fused ring structure
rather than fatty acids
, FATTY ACIDS (FA)
Long chain carboxylic acids
12-20 hydrocarbon LINEAR chains (most even number)
No hydrogen bonds form between the carboxylic acid functional group
o Fatty Acids interact through hydrophobic interactions
By nature, fatty acids are AMPHIPATHIC – have both hydrophilic and hydrophobic parts
Often have double bonds
TWO TYPES
Saturated – hydrocarbon has NO double bonds
Unsaturated – Hydrocarbon chain has ONE or MORE DOUBLE BONDS
o Double bonds are “cis” configuration
o Cause a kink or bend in the chain
o monounsaturated -contain one double bonds
o polyunsaturated - contain more than one double bond
They are essential fatty acids that cannot be synthesized in the human body
and must be taken in adequate amounts in the diet.
They are required for normal growth and metabolism
Dr. Joan Simam
Objectives
1. Definition and functions of lipids
2. Classification of lipids
3. Chemical properties of lipids
Definition:
o Lipids are organic compounds formed mainly from alcohol and fatty acids combined
together by ester linkage
o Very important biomolecules
o Insoluble in water
o Soluble in organic solvents and other lipids
o Lipids include fats, butter, ghee, lard, tallow, terpenes, steroids. Also vegetable oils such
as olive oil, corn oil, soybean oil, semsem oil, sun flower oil, cotton feed oil, fish oil
waxes and related compounds
FUNCTIONS OF LIPIDS
Storage molecules for ENERGY (fats and oils)
Structural components of cellular membranes
Protective molecules (waxes)
Hormones
Carrier of vitamins
Intracellular messengers
Pigments
Insulation
FOUR MAIN CLASSES OF LIPIDS
1. Triacylgylcerols (TAGs) – Storage Lipids (non-polar). Also known as triglycerides
2. Phosphoacylglycerols –Membrane Structural Lipids (polar)
3. Sphingolipids – Membrane Structural Lipids (polar)
4. Non-saponifiable Lipids – Steroids, hormones, cholesterol. Based on a fused ring structure
rather than fatty acids
, FATTY ACIDS (FA)
Long chain carboxylic acids
12-20 hydrocarbon LINEAR chains (most even number)
No hydrogen bonds form between the carboxylic acid functional group
o Fatty Acids interact through hydrophobic interactions
By nature, fatty acids are AMPHIPATHIC – have both hydrophilic and hydrophobic parts
Often have double bonds
TWO TYPES
Saturated – hydrocarbon has NO double bonds
Unsaturated – Hydrocarbon chain has ONE or MORE DOUBLE BONDS
o Double bonds are “cis” configuration
o Cause a kink or bend in the chain
o monounsaturated -contain one double bonds
o polyunsaturated - contain more than one double bond
They are essential fatty acids that cannot be synthesized in the human body
and must be taken in adequate amounts in the diet.
They are required for normal growth and metabolism
