Question

Two monomers in maltose are:
(A)- $\alpha $-D-Glucose and $\alpha $-D-Fructose
(B)- $\alpha $-D-Glucose and $\alpha $-D Galactose
(C)- $\alpha $-D-Glucose and $\alpha $-D-Glucose
(D)- $\alpha $-D-Glucose and $\beta $-D-Glucose

Answer 1

Hint: The basic fundamental unit of polymers, which are the building blocks of proteins is known as a monomer. A monomer reacts with another monomer to form a polymer or a very large molecule by the process known as Polymerisation. Bifunctional monomers on reaction can form only straight chain or linear polymers but monomers of higher functionality form cross-linked polymers.


Complete Step by step answer:

-The IUPAC defines a monomer molecule as a molecule that can undergo polymerization, thereby contributing units to the essential structure of a macromolecule.

-Carbohydrates are essential macromolecules which have the general formula as to ${{(C{{H}_{2}}O)}_{n}}$where n represents the number of carbons in the molecule.

-The carbon to hydrogen to oxygen ratio in a carbohydrate molecule is 1:2:1.

-Carbohydrates are based on saccharide (sugar) units further as – monosaccharides, disaccharides, and polysaccharides.

-Monosaccharides are the simple sugars in which the number of carbons usually ranges from 3 to 7. If an aldehyde group is present on the sugar then it is known as an aldose, and if it has a ketone group, then it is known as a ketose. Monosaccharides based on carbon atoms are further classified as trioses, tetroses, pentoses, hexoses, and heptoses.

-When two monosaccharides undergo dehydration or a condensation reaction, disaccharides are formed. Common disaccharides are lactose, maltose, and sucrose.

-Maltose, is also known as maltobiose or malt sugar is a disaccharide unit formed when two glucose units are joined.

-Glucose is a hexose saccharide which contains six carbon atoms.

-In maltose, the glycosidic oxygen atom of one glucose is $\alpha $and is bonded to the c-4 atom of another
glucose unit which is the aglycone, therefore maltose is an $\alpha $-1,4-glycoside.

So, the correct answer is option C.


Note: Glucose is an optically active molecule, hence it has two constitutional isomers, that is D-glucose and L-glucose. D-glucose rotates the plane polarized light to clockwise or to the right side, while L-glucose rotates the plane polarized light to anticlockwise or left side. D-glucose has two anomers, alpha-D glucose and beta-D glucose. Anomers are saccharides which differ from each other at anomeric carbon. Anomers are capable of inverting solutions.