Heavily summarised notes for biological molecules (lipids) personally summarised

Outline

- Introduction

- Types of lipids

- Structure of lipids

- Functions of lipids

- Test for lipids

I. INTRODUCTION

- Lipids are a loosely defined group of molecules with one main characteristic: they are insoluble in water but soluble in organic solvents (e.g. chloroform).

- Lipids consist of carbon, hydrogen and oxygen - but much less oxygen compared to hydrogen.

- No generalized formula

- Difference between a fat and an oil:

- If a lipid is in the solid state at 20oC, it is a fat.

- If it is in the lipid state at 20oC, it is an oil.

II. TYPES OF LIPIDS

1. Simple lipids

- Esters of fatty acids with various alcohol.

- Fats - esters of fatty acids with glycerol (e.g. triglyceride)

- Waxes - esters of fatty acids with complex alcohol.

2. Compound lipids

- Lipid + non-lipid components.

- E.g.

Image of several fatty acid molecules created by m...

Lipid pneumonia, exogenous, chronic

English: Transesterification of triglycerides with...

Phospholipids = lipids made up of fatty acids + alcohol (e.g.glycerol)

+ phosphate

III. STRUCTURE OF LIPIDS

􀂃 Components of lipids : fatty acids + glycerol

- A fatty acid consists of : a hydrocarbon chain and a carboxyl group.

- A hydrogencarbon chain consists of : a chain of carbon atoms to which hydrogen atoms are attached (vary in length, but most common are even numbered chains of 14 to 20 carbons).

- Glycerol is an alcohol with three carbons, each bearing a hydroxyl group.

􀂃 Synthesis of a triglyceride

- Three fatty acid molecules + one molecule of glycerol.

1

IV. FUNCTIONS OF LIPIDS

1. Triglycerides is a storage form of energy.

2. Good thermal insulator - to prevent excessive heat lost

3. To protect delicate organs

4. As a component of cell membrane

V. TEST FOR LIPIDS

􀂃 Principle:

- Lipids are readily soluble in...