Introduction

Lipids represent a large group of molecules which consist almost entirely of carbon and hydrogen atoms.  They include fats, oils, phospholipids, and steroids. A key distinguishing feature of lipids is the fact that they are insoluble in water – a characteristic termed ‘hydrophobic’ which means “water fearing” (hydro = water; phobic = fearful).

Lipids have a number of functions in cells. They provide long term storage for energy and they serve as an insulation layer for water mammals. Their hydrophobic nature help keep plants and animals dry in wet environments. Many hormones are composed of lipids and lipids are an important component of cellular membranes.

The key functions of lipids in biological systems include:

• Energy Storage
• Water Barrier/Protection
• Cell Membranes
• Hormones

An introduction to lipids video:

Summary

• Lipids are water-insoluble molecules which can be categorized into several groups. These water-insoluble substances consist entirely of carbon, hydrogen and oxygen atoms.
• The Oils, fats and waxes are assembled from fatty acid chains combined with a 3-carbon glycerol molecule.
• Oils, fats and waxes are used in biological systems primarily for energy storage (fats, oils) or for protection (waxes).
• Fats and waxes are solid at room temperature while oils are liquid.
• Fats and waxes are ‘saturated ‘, while liquids are ‘unsaturated ‘.
• Phospholipid molecules have two distinct ends. A hydrophobic (water-hating) end and a hydrophilic (water-loving) end. This makes it a perfect molecule in forming a cell membrane.
• Cholesterol is the most common steroid found in the human body.

Source:

“Introduction to Lipids.” Kahn Academy. Retrieved from: https://youtu.be/HGg_WiaSr4U Licensed under: Standard YouTube License