Question
Explain the structure of starch.

Answer

Starch is found in cereal grains, roots, tubers, potatoes, etc. It is a polymer of $\alpha$-D-glucose and consists of two components, amylose and amylopectin.

Amylose is water soluble component forms blue coloured complex with iodine. It constitutes about $20 \%$ of starch. Amylose contains 200 to $1000 \alpha$-D-glucose units linked together by glycosidic linkage between C-I of one unit and C-4 of another unit. i.e. $\alpha-1,4$ glycosidic linkages.

Image

Amylopectin is insoluble in water and constitutes about $80 \%$ starch which forms blue-violet coloured complex with iodine. It is a branched chain polymer. In amylopectin, $\alpha$-D-glucose molecules are linked together by glycosidic linkage between $C _1$ - of one unit and $C -4$ of another unit to form long chain and branching acurs by glycosidic linkage between C-I and C6 glycosidic linkage.

Image

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free