Lipids and carbohydrates are the bodies energy storage molecules. Carbohydrates are used for quick energy, where as fats are used slow energy releases. On a weight basis, fat stores twice as much energy as the same weight of polysaccharides.

To illustrate the slow burning nature of fats observe the video bellow. The Crucible

 on the left has 20 grams of sugar, while the  Crucible on the right has only 10 grams of vegtable oil. Notice how much longer it takes for the oil to completley burn out compared to the sugar.

Another common lipid is a Phospholipid. No doubt you would have heard of this, as it is the main component of all membranes within the cell.

   Phospholipids have:

• Two fatty acids attached to a glycerol molecule

• Phosphate molecule attached to the glycerol molecule.

Notice the double bond between the Carbon molecules. One of the fatty acid chains is saturated (has no carbon-carbon double bonds), giving it a linear structure, while the other is an unsaturated fatty chain with a carbon-carbon double bond. This double bond is the reason our cells can diffuse nutrients and survive. Without this, we would not be alive.

This kink in the phospholipid spaces out the phospholipids, creating a fluid like structure. If there was no link and these fatty acid tails where straight, then the cell membrane would be much thicker, preventing molecules from easily diffusing in and out.

The phosphate molecule is polar (dissolves easily in water) and makes the head hydrophilic. This means it is attracted to water.

As with all fats, they are non-polar and thus hydrophobic. This means the tails are water fearing.

To learn more about Polar and non-polar click here

Saturated fat – fatty acids which contain one single bond between the carbon atom. Single bonds are more difficult for the body to break down than double bonds, and thus can withstand high temperatures (This is why we often cook with them).

 Unsaturated fat –contain a double bond between carbon to carbon bonds.

 Polyunsaturated fat – contain multiple double carbon atoms.

Uses

Click here for a practical on energy in food

The animation bellow illustrates the formation of a triglyceride.

The Glycerol molecule (carbohydrate) is on the left, and the three fatty chains are on the right.

Fats have multiple functions within the body and play in important part in health.

Fat molecules are often made of fatty acids and glycerol. The most common is a triglyceride. 3 fatty acid tails and one glycerol head.

Fats have been used for many different things, through out time.

On the right you can see a candle. You can make one yourself.

1. Bend a paper clip into a stand
2. Tie a piece of string to the paper clip
3. Submerge the paperclip and string into vegetable oil
4. Allow the string to sit out of the oil and light it up

The string should burn for a while. This demonstrates how fat is a slow burning energy.

In modern times we have invented new ways to use lipids. By using the Hydrophobic nature of lipids, we have created a spray which is super hydrophobic.

Observe the video bellow. The cardboard has been coated with a super hydrophobic spray. This spray is composed of heavy oils and other hydrophobic chemicals. Notice how the Thousand island sauce dose not mix or attract to the cardboard at all.