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प्रश्न
Discuss the optical activity of lactic acid.
उत्तर
(1) Lactic acid contains one asymmetric carbon atom which is attached to four different groups, COOH, CH3, OH and H.
(2) Two different arrangements of these groups around the carbon atom are possible as shown in the figure. Hence, it exist as a pair of enantiomers. The two enantiomers are mirror images of each other and are non-superimposable.
(3) Hence, lactic acid can exist in two different forms, d-Form and l-form, which are non-superimposable mirror images of each other. d-form rotates the plane of plane-polarized light to the right, while l-form rotates the same to the left.
(4) A mixture containing equimolar amounts of the d- and l-forms is a racemic mixture which is optically inactive (dl - form). This inactivity arises due to external compensation.
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संबंधित प्रश्न
What is peptide linkage?
Define the following as related to proteins
Peptide linkage
What are the common types of secondary structure of proteins?
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Fibrous proteins and Globular proteins
Differentiate between the following :
Peptide linkage and Glycosidic linkage
Which of the following biomolecules is insoluble in water?
The protein responsible for blood clotting is ____________.
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Dinucleotide is obtained by joining two nucleotides together by phosphodiester linkage. Between which carbon atoms of pentose sugars of nucleotides are these linkages present?
Optical rotations of some compounds along with their structures are given below which of them have D configuration.
| (I) |  |
| (II) |  |
| (III) |  |
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
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Structures of glycine and alanine are given below. Show the peptide linkage in glycylalanine.
\[\ce{\underset{(Glycine)}{H2N - CH2 - COOH}}\];
\[\begin{array}{cc}
\ce{H2N - CH2 - COOH}\\
|\phantom{......}\\
\ce{\underset{(Alanine)}{CH3}\phantom{...}}
\end{array}\]
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.
Which moieties of nucleosides are involved in the formation of phosphodiester linkages present in dinucleotides? What does the word diester in the name of linkage indicate? Which acid is involved in the formation of this linkage?
Assertion: β-glycosidic linkage is present in maltose,
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The main structural feature of proteins is
Out of the following, which type of interaction is responsible for the stabilisation of the α-helix structure of proteins?
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An α-helix is a structural feature of ______.
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Reason (R): A tetrapeptide contains 4 amino acids linked by 4 peptide bonds.
What is the effect of denaturation on the structure of proteins?
