Page 30 - 84 human physiolofy part-1

Chapter 2

ketones with many hydroxyl groups added, usually one on each carbon except the functional group.
Other carbohydrates are composed of monosaccharide units and break down under hydrolysis. These
may be classified as disaccharides, oligosaccharides, or polysaccharides, depending on whether they
have two, several, or many monosaccharide units.

Proteins

All proteins contain carbon, hydrogen, oxygen and nitrogen. Some also contain phosphorus and
sulfur. The building blocks of proteins are amino acids. There are 20 different kinds of amino acids
used by the human body. They unite by peptide bonds to form long molecules called polypeptides.
Polypeptides are assembled into proteins. Proteins have four levels of structure

• Primary Primary structure is the sequence of amino acids bonded in the polypeptide.

• Secondary The secondary structure is formed by hydrogen bonds between amino acids.
The polypeptide can coil into a helix or form a pleated sheet.

• Tertiary The tertiary structure refers to the three-dimensional folding of the helix or
pleated sheet.

30 | Human Physiology