• In lipids the number of H atoms is more than the number of O atoms. This is the reason why lipids give more energy.

• They are made up of C, H and O atoms.

LIPIDS

•Lipids are found in all cells.•They are insoluble in water but soluble in non-polar organic solvents such as ether, chloroform, benzene.•Sometimes P and N atoms can join the lipid structure.

LIPIDS

STEROIDSPHOSPHOLIPIDS GLYCOLIPIDSNEUTRAL LIPIDS

(Triglyceride)

The structural units of lipids are glycerol and fatty acids. The type and function of the lipid molecule differs due to the type of fatty acid.

Glycerol + 3 fatty acids

Triglyceride + 3 H2O3ATP

GLYCEROL

O

O

O

H HO

H HO

H HO

fatty acids

fatty acids

fatty acids

3 ATP

enzyme

GLYCEROL

__ O__

__ O__

__ O__

fatty acids

fatty acids

fatty acids

+3H2O

ester linkage

@

enzyme

A) Triglycerides (Neutral Lipids)

GLYCEROL: is an alcohol that has three –OH (hydroxide groups)

FATTY ACIDS: are long chains of H and C atoms. At the end of the chain, there is carboxyl (- COOH) group.

A) Triglycerides (Neutral Lipids)

FATTY ACIDS

Unsaturated Fatty Acids

Saturated Fatty Acids

solid at room temperature

only single C-C bonds occur

ex: butter, lard

liquid at room temperature

one or more double bonds between C atomsex: olive oil, peanut oil, corn oil,sunflower oil

B) Phospholipids

Found in the cell membrane structure

The third fatty acid of fat molecule is replaced by phosphate group.

They have hydrophilic (loves-water) and hydrophobic (hates water)

Hydrophilic (polar because of PO4

-3)

Hydrophobic (non-polar)

B) Phospholipids

B) Phospholipids

B) Glycolipids

Found in the cell membrane structure of neurons

The third fatty acid of fat molecule is replaced by a glucose or galactose molecule.

B) Steroids

They are important in membrane structure and in metabolism. They all have the same backbone made up of carbon rings.

They are lipids without fatty acids.

IMPORTANCE OF LIPIDS

Lipids are great energy sources. They store twice the energy of carbohydrates because they have more H atoms in their structure.

Lipids are used as structural units of cell structure.

Lipids are stored in animal body, under the skin and around the organs. This helps protect the body from mechanical effects and is a long-term energy storage. Also this helps in heat isolation.

Lipids are solvent for A, D, E and K vitamins, so these vitamins can be stored in the body.

Because they include more H atoms than carbohydrates, they result in production of more water molecules when used in aerobic respiration. This provides animals living in dry environments with water.

IMPORTANCE OF LIPIDS

It is thought that fats (saturated fatty acids) increase the level of cholesterol in the blood. High blood cholesterol levels may be linked to atherosclerosis and other heart diseases.

IMPORTANCE OF LIPIDS