Question

Glycosidic linkage present between adjacent glucose units of starch or glycogen is generally-
A. $\beta 1 - {\text{ }}4$
B. $\alpha 1 - {\text{ }}4$
C. $\alpha 2 - 1$
D. $\beta 2 - 1$

Answer 1

A glycosidic linkage, also known as a glycosidic bond, is a form of covalent bond that connects a carbohydrate molecule to another group, which could be another carbohydrate or not. A glycosidic bond is formed between the hemiacetal or hemiketal group of a saccharide of some compound such as an alcohol. Examples will be- Hemiacetal and Hemiketal are formed by glycosidic linkage.

Complete Explanation:
Option A $\beta 1 - {\text{ }}4$: Glycosidic linkage present between adjacent glucose units of starch or glycogen is not Beta linkage as $4$ carbon is linked in the side chain that is true but the beta carbon is not linked.
So, option A is not correct.
Option B $\alpha 1 - {\text{ }}4$: Glycosidic linkage present between adjacent glucose units of starch or glycogen is generally alpha $1 - 4$ linkage. Alpha carbon of the first unit of glucose is linked to the $4$ carbon of another unit of glucose is linked to the $4$ carbon of another unit of glucose of the side chain.
So, option B is correct
Option C $\alpha 2 - 1$: Most of the glucose units in glycogen are linked by alpha $1$,$4$ glycosidic bonds. The branches are formed by alpha $1$,$6$ glycosidic bonds, present about once in $10$ units. Hence, this is not the correct answer.
Option C is not correct.
Option D $\beta 2 - 1$: Glycosidic linkage present between glucose and starch units are generally bonded by alpha carbon chain not the beta carbon chain. And it is linked by $4$ carbon units.
Option D is not correct.

Hence, Option B is the correct answer.

b>Note:**
Hence it is discussed that alpha $1$,$4$ glycosidic linkage is present between the respective glucose and starch units. In humans both glucose and starch both are stored in glycogen. Glucose is the simplest form of carbohydrate so; it gets easily absorbed by the digestive tract of the organism. Whereas starch is a complex form of glucose it takes time to get absorbed.