Question

There are a number of different enzymes in the gastrointestinal (GI) tract that digest carbohydrates. Cellulose is a carbohydrate that is not digestible, why is this? a) Cellulose is itself an individual subunit and so does not need to be broken down further b) Cellulose is not made up of glucose subunits and so cannot be broken down in the GI tract Oc) Cellulose has glycosidic bonds between its subunits that we do not have an enzyme to break d) Cellulose can't be unfolded in the stomach, so pepsin is unable to break it down

Answer 1

The Correct answer will be option 'c' i.e. cellulose has glycosidic bonds between its subunits that we do not have an Enzyme to break. Cellulose is the polysaccharide consisting of many glucose units as monosaccharide. Glucose subunits are linked by beta glycosidic bond ($\beta$ 1$\rightarrow$4 linkage). Cellulose is undigestable because we don't have proper enzyme to break beta glycosic bond, making cellulose unbreakable and difficult to digest.