Classify the following proteins based on their molecular shapes.
(a) Collagen
(b) Albumin
(c) Haemoglobin
(d) Myosin

Hint: Proteins are natural polymers and formed by the polymerization of amino acids with a peptide bond $-CO-N{{H}_{2}}$. Polymers are macromolecules built up by linking together a large number of small molecules which are known as monomers.

Complete answer:
Polymers are classified based on the source are natural polymers and synthetic polymers.
Natural polymers: the polymers which are abundant in nature like proteins, cellulose, starch, silk, and natural rubber.
Synthetic rubber: the polymers which are synthesised by man-made or in laboratories or in industries. For examples, synthetic rubbers, silicone rubber, plastic and synthetic fiber, etc.
Naturally occurring proteins have an amino acid composition of their own characteristics with a unique three-dimensional shape. Due to their complexity in specific structure similarities in proteins, it is very difficult to classify them.
The two major structural classifications based on the solubility and structure of proteins are fibrous which is insoluble and globular which is soluble.
The fibrous proteins are insoluble in water and usually linear in structural, connective, and protective functions. Examples of this type of protein are collagen with connective tissue and myosins are capable of contractions and extension.
So, collagen and myosins belong to the type of fibrous proteins.
Globular proteins chain like roughly spherical and familiar examples are albumin from egg and Hemoglobin which is important for binding oxygen.

Note:
There are three criteria for polymers classification. Those are classification based on the structure of a protein, composition of protein, and functions of proteins. The hydrolysis of proteins yields only amino acids and small carbohydrate compounds.