# How do lipids differ from carbohydrates and proteins?

Jun 13, 2015

Lipids are hydrophobic and insoluble in water. Carbohydrates and proteins are hydrophilic and able to form hydrogen bonds with water.

#### Explanation:

Lipids

Lipids have varied structures, but all have a polar "head" and a large nonpolar "tail"".

Fats and oils are typical lipids.

The structure of a typical fat is

The molecule is mostly nonpolar hydrocarbon with some polar $\text{C=O}$ groups at one end.

Proteins

Proteins are large molecules that consist of long chains of amino acids joined together by peptide ($\text{CONH}$) bonds.

The structure of a small protein is

Proteins have polar $\text{C=O}$ and $\text{N-H}$ groups, so they are able to form hydrogen bonds with other molecules and with each other.

Carbohydrates

Carbohydrates have many polar $\text{OH}$ groups.

A typical carbohydrate is starch, which is consists of many glucose units (${\text{C"_6"H"_12"O}}_{6}$) joined together.

Most carbohydrates are hydrophilic and soluble in water because of their polar $\text{OH}$ groups.