# How do proteins differ from carbohydrates and lipids?

Jun 13, 2015

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

#### Explanation:

Proteins

The structure of a small protein is

Proteins have polar C=O and 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.

Lipids

Lipids are hydrophobic and insoluble in water.

They 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.