Why can't humans digest cellulose?
Why can't humans digest cellulose?
| A: Humans have an enzyme present in their body, amylase, that hydrolyzes ß-1,4-glycosidic bonds but not the α-1,4-glycosidic bonds of cellulose. |
| B: Cellulose is present in wood and only bugs like termites can digest cellulose. |
| C: Human teeth are not strong enough to break the wood fibers that are formed by the long chains that are formed by the repeating units of the monosaccharides. |
| D: Humans have an enzyme present in their body, amylase, that hydrolyzes α-1,4-glycosidic bonds but not the ß-1,4-glycosidic bonds of cellulose. |
Answer
ANS: Option (D)
Cellulose is a polysaccharide which contains glycosidic linkages
between its monomers. Out of the two types of glycosidic bonds,
Cellulose contains 
-1,4-glycosidic bonds. Enzymes like Amylase inside our body is
responsible for the breakdown of glycosidic bonds of
polysaccharides into smaller molecules like glucose, fructose
etc.through a process called Digestion.
But,
inside the human body enzymes like Amylase breaks the
-1,4-glycosidic bonds present in starch or glycogen rather than
the
-1,4-glycosidic bonds in Cellulose. Due to this reason, we humans
cannot digest Cellulose.
We were unable to transcribe this image
We were unable to transcribe this image
We were unable to transcribe this image
Starch a(1-- 4)-glycosidic linkage "СН,ОН 6CH,OH °CН,ОН Н/ ОН Н ОН Н/ ОН НД - ОН н ОН 1 ОН a-D-glucopyranose Cellulose B(1-4)-glycosidic linkage 6СН,ОН — О. ОН 6CH,OH HЛ н — (OH об Н бСН,ОН н . н ОН он —О о 7 72 Пон н н ОН Н Н ОН B-D-glucopyranose