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प्रश्न
Differentiate between the following:
Fibrous proteins and Globular proteins
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उत्तर १
| Fibrous protein | Globular protein |
| It is a fibre-like structure formed by the polypeptide chain. These proteins are held together by strong hydrogen and disulphide bonds. | The polypeptide chain in this protein is folded around itself, giving rise to a spherical structure. |
| It is usually insoluble in water. | It is usually soluble in water. |
| Fibrous proteins are usually used for structural purposes. For example, keratin is present in nails and hair; collagen in tendons; and myosin in muscles. | All enzymes are globular proteins. Some hormones such as insulin are also globular proteins. |
उत्तर २
Fibrous proteins: These proteins consist of linear thread like molecules which tend to lie side by side (parallel) to form fibres. The polypeptide chains in them are held together usually at many points by hydrogen bonds and some disulphide bonds. As a result,intermolecular forces of attraction are very’ strong and hence fibrous proteins are insoluble in water. Further, these proteins are stable to moderate changes in temperature and pH. Fibrous proteins serve as the chief structural material of animal tissues.For example, keratin in skin, hair, nails and wool, collagen in tendons, fibrosis in silk and myosin in muscles.
Globular proteins: The polypeptide chain in these proteins is folded around itself in such a way so as to give the entire protein molecule an almost spheroidal shape. The folding takes place in such a manner that hydrophobic (non-polar) parts are pushed inwards and hydrophilic (polar) parts are pushed outwards. As a result, water molecules interact strongly with the polar groups and hence globular protein are water soluble. As compared to fibrous proteins, these are very sensitive to small changes of temperature and pH. This class of proteins include all enzymes, many hormones such as insulin from pancreas, thyroglobulin from thyroid gland, etc.
संबंधित प्रश्न
Discuss the optical activity of lactic acid.
Define the following as related to proteins:
Peptide linkage
Write one difference between α-helix and β-pleated structures of proteins.
Which of the following biomolecules is insoluble in water?
Which functional group participates in disulphide bond formation in proteins?
Proteins are found to have two different types of secondary structures viz. α-helix and β-pleated sheet structure. α-helix structure of protein is stabilised by:
Dinucleotide is obtained by joining two nucleotides together by phosphodiester linkage. Between which carbon atoms of pentose sugars of nucleotides are these linkages present?
Proteins can be classified into two types on the basis of their molecular shape i.e., fibrous proteins and globular proteins. Examples of globular proteins are:
(i) Insulin
(ii) Keratin
(iii) Albumin
(iv) Myosin
Which of the following are purine bases?
(i) Guanine
(ii) Adenine
(iii) Thymine
(iv) Uracil
α-Helix is a secondary structure of proteins formed by twisting of polypeptide chain into right-handed screw like structures. Which type of interactions are responsible for making the α-helix structure stable?
Protein found in a biological system with a unique three-dimensional structure and biological activity is called a native protein. When a protein in its native form, is subjected to a physical change like change in temperature or a chemical change like, change in pH, denaturation of protein takes place. Explain the cause.
Explain the terms primary and secondary structure of proteins. What is the difference between α-helix and β-pleated sheet structure of proteins?
Explain formation of peptide linkage in protein with an example.
Proteins are polymers of ______.
β-pleated sheet structure in proteins refers to ______.
Write a classification of proteins with an example.
Match List I with List II:
| List I | List II |
| A. GLUT-4 | I. Hormone |
| B. Insulin | II. Enzyme |
| C. Trypsin | III. Intercellular ground substance |
| D. Collagen | IV. Enables glucose transport into cells |
Choose the correct answer from the options given below:
Statement I: A protein is imagined as a line, the left end represented by first amino acid (C-terminal) and the right end represented by last amino acid (Nterminal).
Statement II: Adult human haemoglobin, consists of 4 subunits (two subunits of a type and two subunits β type.)
In the light of the above statements, choose the correct answer from the options given below:
