Advertisements
Advertisements
Question
Discuss the optical activity of lactic acid.
Advertisements
Solution
(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.
APPEARS IN
RELATED QUESTIONS
How are proteins classified on the basis of molecular shapes?
Define the following as related to proteins:
Peptide linkage
What type of bonding helps in stabilising the α-helix structure of proteins?
Differentiate between the following:
Fibrous proteins and Globular proteins
Write one difference between α-helix and β-pleated structures of proteins.
Differentiate between the following :
Peptide linkage and Glycosidic linkage
Which of the following biomolecules is insoluble in water?
The helical structure of protein is stabilized by:
The correct statement for protein haemoglobin.
Which functional group participates in disulphide bond formation in proteins?
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
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.
Assertion: β-glycosidic linkage is present in maltose,
Reason: Maltose is composed of two glucose units in which C–1 of one glucose unit is linked to C–4 of another glucose unit.
Explain the terms primary and secondary structure of proteins. What is the difference between α-helix and β-pleated sheet structure of proteins?
The main structural feature of proteins is
Each polypeptide in a protein has amino acids linked with each other in a specific sequence. This sequence of amino acids is said to be ______.
The correct structure of Ruhemann's Purple, the compound formed in the reaction of ninhydrin with proteins is:
The total number of negative charge in the tetrapeptide, Gly-Glu-Asp-Tyr at pH 12.5 will be ______. (Integer answers)
Proteins are polymers of ______.
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:
