Lipids: a large and varied group of organic compounds.

Lipids include:

Triglycerides

Lipids: a large and varied group of organic compounds.

Triglycerides include Phospholipids

Triglycerides consist of one molecule of glycerol bonded to three fatty acid molecules

Each fatty acid is linked to the glycerol molecule by an ester bond

C C C

H

OH

H

H H

H

OH OH

Glycerol

Hydroxyl groups

Fatty Acids:

General Formula: CH3 (CH2)n C

O

OH

Carboxyl group

H C C C

H

H

H H

H H

C C C

H

H

H H

H H

C

O

OH

CH3 CH2

H C C C

H

H

H H

H H

C C C

H

H

H H

H H

C

O

OH

Can be drawn as:

C

O

OH

A cis fatty acid

A trans fatty acid

LDL bad

HDL good

Forming a monoglyceride:

C

C

C

H OH

H

H

H

H

OH

OH

C

O

OH

C

C

C

H OH

H

H

H

H

OH

O C

O

+ H2O

Ester bond

Hydroxyl group and carboxyl group react

This is a condensation reaction

C

C

C

H O

H

H

H

H

O

O C

O

C

O

C

O

A triglyceride:

Can be drawn as:G

lyce

rol

Fatty acid

Fatty acid

Fatty acid

Ester bond

To split these ester bonds and separate a fatty acid from glycerol we need to add a molecule of water

C

C

C

H OH

H

H

H

H

OH

O C

O

+ H2O

C

C

C

H OH

H

H

H

H

OH

OH

C

O

OH

This is a hydrolysis reaction

Lipids: a large and varied group of organic compounds.

Lipids include: Cholesterol

Uses of Lipids in Living Things

1. Long-term energy stores

Human Adipose Tissue Plant Oils

2. Buoyancy for marine animals: lipids are less dense than water so help animals float

3. Insulation: a layer of fat beneath the skin cuts down heat loss

4. Production of water: fatty acids produce a lot of metabolic water when they are oxidised during respiration

e.g. C17H35COOH + 26 O2 18 CO2 + 18 H2O (a typical fatty acid)

Camels’ humps are made of fat