In fibrous proteins, polypeptide chains are held together by ___________.

a)
van der Waals forces

b)
disulphide linkage & hydrogen bonds

c)
electrostatic forces of attraction

d)
None of these

Correct answer is option 'B'. Can you explain this answer?

Question

In fibrous proteins, polypeptide chains are held together by ___________.

a)
van der Waals forces
b)
disulphide linkage & hydrogen bonds
c)
electrostatic forces of attraction
d)
None of these

Correct answer is option 'B'. Can you explain this answer?

Answer

The correct answer are options B & D,
In fibrous proteins, polypeptide chains are held together by hydrogen and disulphide bonds, in parallel manner. Due to which fibre-like structure is obtained. Such proteins are generally known as fibrous proteins. These proteins are generally insoluble in water e.g., keratin, myosin.

Answer

Generally the polypeptides of globular proteins in our body are linked with each other by hydrogen bonding

Answer

Why not A?

Answer

Introduction:
Fibrous proteins are a type of structural proteins that play a crucial role in maintaining the shape and function of cells and tissues. They are characterized by their elongated and insoluble structure, which provides strength and support to various biological structures. The polypeptide chains in fibrous proteins are held together by disulfide linkages and hydrogen bonds.

Disulfide Linkages:
Disulfide linkages are covalent bonds formed between two cysteine amino acids. Cysteine contains a sulfhydryl (-SH) group, which can undergo oxidation to form a disulfide (-S-S-) bond. These disulfide linkages contribute to the stabilization and structural integrity of fibrous proteins. They provide strength and resistance to stretching forces, making fibrous proteins highly durable and resilient.

Hydrogen Bonds:
Hydrogen bonds are formed between a hydrogen atom and an electronegative atom, such as oxygen, nitrogen, or fluorine. In fibrous proteins, hydrogen bonds occur between the peptide bonds of the polypeptide chains. The oxygen atom of one peptide bond forms a hydrogen bond with the hydrogen atom of another peptide bond. These hydrogen bonds are relatively weak compared to covalent bonds but play a crucial role in maintaining the secondary and tertiary structure of fibrous proteins.

Secondary Structure:
The primary structure of a protein refers to the linear sequence of amino acids in a polypeptide chain. The secondary structure refers to the local folding patterns within the polypeptide chain, primarily involving the formation of alpha helices and beta sheets. These secondary structures are stabilized by hydrogen bonds between the peptide bonds. The oxygen atom of one peptide bond forms a hydrogen bond with the hydrogen atom of a peptide bond located a few amino acids away. This regular pattern of hydrogen bonding results in the formation of stable secondary structures.

Tertiary Structure:
The tertiary structure of a protein refers to the overall three-dimensional arrangement of the polypeptide chain. In fibrous proteins, the tertiary structure is relatively simple, mainly consisting of long, parallel or antiparallel polypeptide chains. The tertiary structure is stabilized by disulfide linkages, which form covalent bonds between cysteine residues in different parts of the polypeptide chain. These disulfide linkages help maintain the overall shape and stability of the fibrous protein.

Conclusion:
In conclusion, fibrous proteins are held together by disulfide linkages and hydrogen bonds. Disulfide linkages provide strength and resistance to stretching forces, while hydrogen bonds contribute to the stabilization of secondary structures and the overall shape of the protein. These interactions play a crucial role in maintaining the structural integrity and functionality of fibrous proteins.

Similar Class 12 Doubts

What is incorrect about fibrous proteins

When the polypeptide chain runs parallel and are held together by hydrogen and disulphide bond then the proteins formed is

In which of the following solids, ions of opposite charges are held together by strong electrostatic forces of attraction?

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