Question

A compound isolated from a biological source is subjected to chemical analysis. It contains carbon and oxygen in roughly equal amounts and hydrogen in an amount that is almost twice that of carbon. This compound does not take up iodine stain very well, indicating that its structure is densely packed and resistant to large molecules binding to it through noncovalent interactions. What is the likely identity of this compound?a. Monosaccharideb. Glycogenc. Starchd. Triglyceride

Answer 1

Answer:B (glycogen)

Explanation:

Starch is in the form of amylose and amylopectin has less branches than glycogen. Glycogen is more branched and more compact than amylopectin of starch. glycogen is composed of glucose units joined by alpha-1,4 links in the straight chain and alpha-1, 6 glcosidic linkages at the branch point. Iodine atoms can bind into the helices of starch and glycogen to form a starch-iodine or glycogen-iodine complex respectively. The helices of starch are longer than glycogen, and therefore can bind more iodine atoms. The is the reason why color produced by a starch-iodine complex(blue black) is more intense than that obtained with a glycogen-iodine complex.