Protein Structure

Proteins are large polymers.

Proteins and large polymers made up of the monomer amino acids.

Proteins, figure 1

Amino acid (R is the group that is different on all 20 amino acids)

These amino acids are arranged in a series of structures to create the finished 3D protein. There are up to four levels of structural arrangements in a protein, see the image below, which will each be explained fully.

Proteins, figure 2

Proteins polymer chains, or polypeptides, are created on the ribosome in cells and are then further folded and modified in the Golgi apparatus.

Primary Structure

The first structure that forms in the creation of a protein is the polypeptide chain. Proteins are all made up of one or more polypeptide chain folded into highly specific 3D shapes. The exact definition of a primary structure is:

[mkdf_blockquote text=”The sequence of amino acids in a polypeptide chain”]

This would be a one-mark question and it is essential that you state the word ‘sequence’. The order the amino acids are bonded in is determined by DNA. This specific order of amino acids will alter how the protein further folds and is bonded enabling unique functions.

There are 20 different amino acids that can form the primary structure. The polypeptide chain is created by a series of condensation reactions occurring between amino acids.

Proteins, figure 1