Biological Functions Of Proteins: Roles, Function, Importance

What are Proteins?

Proteins are long-chain molecules made of amino acids that are very vital in the body and are involved in many activities within the body. Proteins are made out of 20 different types of amino acids that are characterised by an amino group (NH2), carboxyl group (COOH), hydrogen atom, and a variable R group that varies depending on the type of amino acid. An important fact that defines it is the uniqueness of amino acids’ sequence and structure, which determines their function in biological processes.

Structure of Protein

To create protein structures, amino acids condense and form peptide bonds. A peptide bond (-CO-NH) is created between the amine group of one molecule and the carboxyl group of the neighboring molecule, which is followed by the elimination of a water molecule. If not, this connection is an amide one. A polypeptide chain is created when peptide bonds are established between more than ten amino acids. A protein is produced when a polypeptide chain has a mass of more than 10,000 u and more than 100 amino acids.

Different Types Of Structure Of Proteins

Primary Structure: The arrangement of amino acids that make up a polypeptide chain is known as the fundamental structure. Twenty different amino acids make up proteins. A protein's fundamental sequence is the arrangement of its amino acids.

Secondary Structure: The secondary structure of a protein refers to the regular, recurring folding patterns that make up its backbone. The beta-sheet and the alpha-helix are the two most prevalent folding patterns. One of the most common methods for a polypeptide chain to produce all available hydrogen bonds is the helix, which involves twisting into a right-handed screw and hydrogen-bonding each amino acid residue -NH group to the -CO of the subsequent helix turn.

Tertiary Structure: The tertiary structure is the whole polypeptide chain folded into a precise 3D form. A compact, spherical tertiary structure is typical of enzymes.

Quaternary Structure: Polypeptide chains make up a large portion of proteins. The arrangement of the different subunits to create the overall structure is described by the quaternary structure of a protein.

Functions Of Protein

Proteins are essential for carrying out complicated activities as well as for the synthesis and renewal of DNA. Proteins are called enzymes to help break down food. Cells interact with one another and with the outside environment through surface receptors. Proteins make up these receptors.

Enzymes as Proteins

The enzymes that aid in digestion are specific proteins. To put it another way, they break down nutrients into their essential monomeric components. The digestive enzymes pepsin and amylase are two examples.

Structural Proteins

Proteins that are essential because they make up parts of some structures. Tubulin and keratin are two examples.

Hormonal Proteins

Numerous hormones that aid in controlling how the body works. One such instance is insulin.

Transport Proteins

Proteins are essential for moving materials throughout the body. Haemoglobin is one such instance of such a protein.

Defence Proteins

Proteins also play an essential role in the immune system, which defends the body against infections. An illustration of one such protein is immunoglobulin.

Storage Proteins

Albumin and egg white are two proteins feeding the developing embryo.

Biological Role of Protein

Proteins are the fundamental components of life and give living things the structural support they need to develop and flourish. “Protein" comes from the Greek adjective proteos, which means "the most significant." Each protein comprises a lengthy chain of amino acids linked together by peptides. The human body alone may express hundreds of thousands of distinct proteins, although these chains only include 20 different amino acids.

Protein NEET MCQs

Q1. Alpha helix and beta pleated sheets are absent in___

1. Primary Structure

2. Secondary Structure

3. Tertiary Structure

4. Quaternary Structure

Correct answer: 1) Primary Structure

Explanation:

The alpha helix and beta pleated sheets are absent in the primary (1°) structure of proteins, which is simply the linear sequence of amino acids. These structures form later in the secondary structure as the polypeptide chain folds, with hydrogen bonds stabilizing the alpha helix and beta sheets.

Hence, the correct option is 1) Alpha helix and beta pleated sheets are absent in the primary structure.

Q2. The primary structure of a protein molecule has

1. Two ends

2. One end

3. Three ends

4. No ends

Correct answer: 1) Two ends

Explanation:

The primary structure of a protein molecule consists of a specific sequence of amino acids linked by peptide bonds. This sequence is determined by the gene encoding the protein and dictates its overall structure and function. Any change or mutation in the sequence can alter the protein's properties, potentially affecting its biological activity. The primary structure serves as the foundation for the protein's higher-order structures, including secondary, tertiary, and quaternary forms.

Hence, the correct answer is option 1) Two ends.

Q3. The primary structure of protein represents

1. The linear sequence of amino acids joined by peptide bond

2. 3D structure of protein

3. Helical structure of protein

4. Subunit structure of protein

Correct answer: 1) The linear sequence of amino acids joined by peptide bond

Explanation:

The primary structure of protein represents a linear sequence of amino acids joined by a peptide bond. The primary structure of a protein represents a linear sequence of amino acids joined by peptide bonds. It is unique to each protein and serves as the foundation for its higher-order structures, such as secondary, tertiary, and quaternary forms. This sequence is determined by the genetic code within an organism's DNA. The primary structure plays a crucial role in defining the protein's overall shape, stability, and specific biological function. Even a single change in the sequence, caused by a mutation, can alter the protein's activity or lead to diseases. Understanding the primary structure is essential for studying protein folding and function.

Hence, the correct answer is option 1) Linear sequence of amino acids joined by peptide bonds.

Also Read:

• MCQs on Types of Structures of Proteins

• Factors Affecting Enzyme Activity

• Metabolites

FAQs on Protein Functions

What is the biological function of protein?

Proteins are long-chain molecules made of amino acids that are very vital in the body and are involved in many activities within the body. The major roles of proteins include enzymes that catalyse biochemical reactions, the transportation of molecules using haemoglobin, and the structural framework provided by collagen.

What are the main functions of proteins in the body?

• Structural role – Collagen and keratin provide strength to connective tissues, hair, and skin.

• Enzymatic function – Enzymes like amylase and lipase speed up biochemical reactions.

• Transport – Hemoglobin carries oxygen, and membrane proteins transport molecules.

• Hormonal regulation – Insulin and glucagon regulate blood sugar.

• Defense – Antibodies protect the body against infections.

What are the four structures of proteins?

1. Primary structure – The main secondary building block of a protein is its amino acid sequence, held together by peptide bonds to form a polypeptide chain.

2. Secondary structure – The secondary structure is the regular, repeated patterns of the polypeptide chain, primarily stabilized by hydrogen bonds

3. Tertiary structure – The tertiary structure can be defined as the overall form of a polypeptide where the covalent bonds are between the side chains (R groups).

4. Quaternary structure – Quaternary structure is the level of protein structure where several polypeptide chains combine to form a functioning protein complex.

What are examples of proteins and their functions?

• Hemoglobin – Transports oxygen in blood.

• Insulin – Regulates glucose metabolism.

• Keratin – Provides strength to hair and nails.

• Collagen – Maintains structure of connective tissues.

• Antibodies – Provide immunity by fighting pathogens.

• Actin & Myosin – Involved in muscle contraction and movement.