Proteins are chains of amino acids bound together by peptide bonds. Peptide bonds are formed in a hydrolysis reaction between the amine and carboxylic acid groups of the two amino acids. Water is released in this reaction. 

There are two types of protein; Fibrous and globular. Fibrous proteins are usually used for structural functions, while globular proteins are transport or  enzymatic proteins. 

And example of a fibrous protein is collagen. This is found in ligaments and around arteries and veins to provide strength. It is made of three chains of polypeptides in a left handed triple helix. Every third amino acid is glycine - the smallest amino acid - and this can form hydrogen bonds. The position of glycine in the three polypeptides is staggered so that hydrogen bonds can form at every place on the chains. This provides a tight turn in the helix and very high tensile strength. Collagen is also slightly flexible, so it is very good at providing strength in ligaments.

A globular protein is haemoglobin, which is a transport protein found in red blood cells. This protein is made




very helpful thanks :) however peptide bonds are formed with a condensation reaction rather than a hydrolysis reaction.

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