Lipids are organic substances that are insoluble in water. They include fats, oils, fatty acids, triglycerides, and phospholipids. Fats are solid at room temperature while oils are liquid. Fatty acids have a carboxyl head and a hydrocarbon tail. Triglycerides are composed of glycerol bonded to three fatty acids, making them insoluble in water but soluble in organic solvents. They serve as energy sources and insulators. Phospholipids have a polar phosphate head and two hydrophobic fatty acid tails, allowing them to be part of cell membranes.

1. Lipids
• Organic substance
• Insoluble in water
• Are fats and oil
Lipids
Fatty acids
Triglycerides
Phospholipid

2. Fats
Solid at room
temperature
Oil
Liquid at
room
temperature

3. Fatty acids
• Head ( composed by carboxyl group or – COOH )
• Tail ( Hydro carbon Tail or a tail of carbon atoms )

4. Fatty acids
Unsaturated
Doublebonds
between carbon
Melt more easily
Oil
Mostly in plant
Saturated Don`t have
double bonds
Found in animals
fats

6. Unsaturated
Polyunsaturated
More than on
double bond
Monosaturated
Only one double
bond

7. Triglycerides
Glycerol + 3 fatty acid Triglycerides
• Glycerol is an alcohol with 3 – OH
• The reaction between an alcohol and an acid produces an
ester
Triglycerides :
* are ester
• Insoluble in water
• Are soluble in certain organic solvents like
- ether
- chloroform
- ethanol
• non- polar nature
• Hydrophobic

8. Function of the Triglycerides
1. Energy source because have a lot of C- H bonds
2. Stored below dermis around kidneys and act as shock absorber
3. Insulator of the heat
4. Metabolic source of water ( dry habits animals)

9. Formation of the triglycerides

10. Phospholipids
• The head is polar because of phosphate group
• Two hydrophobic fatty acid tail
• The head loves water
• Are part of the cell membrane