Question

Write the name of basic building units of proteins and nucleic acids. How can you differentiate between Fibrous and Globular proteins on the basis of their structures ?

Hint:

Proteins are polymers of amino acids whereas nucleic acids are polymers of nucleotides. Fibrous proteins provide structural support while globular proteins mainly perform functional roles in living organisms.

Answer 1

Concept: Proteins and nucleic acids are important biological macromolecules essential for the growth, development and maintenance of living organisms. Although these biomolecules are very large and complex, they are formed by the repetition of smaller units known as monomers or building blocks. Understanding these fundamental building units helps in understanding the structure and functions of biomolecules in living systems.

Step 1: Basic building unit of proteins Proteins are naturally occurring polymers formed by the condensation of a large number of \(\alpha\)-amino acids. Each amino acid contains:

• An amino group (\(-NH_2\))

• A carboxyl group (\(-COOH\))

• A hydrogen atom

• A side chain (\(R\)-group)
The amino acids are linked together by peptide bonds to form proteins. Therefore, the basic building units of proteins are: \[ \boxed{\alpha\text{-amino acids}} \]

Step 2: Basic building unit of nucleic acids Nucleic acids such as DNA and RNA are polymers made up of repeating units called nucleotides. Each nucleotide consists of:

• A nitrogenous base

• A pentose sugar

• A phosphate group
Therefore, the basic building units of nucleic acids are: \[ \boxed{\text{Nucleotides}} \]

Step 3: Difference between Fibrous and Globular proteins Proteins are classified according to their molecular shape into fibrous proteins and globular proteins.

Fibrous Proteins

• Long and thread-like in structure.

• Polypeptide chains are arranged parallel to one another.

• Generally insoluble in water.

• Mainly perform structural functions.

• Examples: Keratin, Collagen.

Globular Proteins

• Compact and spherical in shape.

• Polypeptide chains are folded into complex three-dimensional structures.

• Usually soluble in water.

• Mainly perform biological functions such as transport and catalysis.

• Examples: Haemoglobin, Insulin.

Final Answer: \[ \boxed{\text{Proteins are made of }\alpha\text{-amino acids}} \] \[ \boxed{\text{Nucleic acids are made of nucleotides}} \] Fibrous proteins possess long thread-like structures whereas globular proteins possess compact spherical structures.