Step 1: Understanding the Concept: Carbohydrates are polymers composed of monosaccharide units linked together by glycosidic bonds.
The spatial orientation of these bonds (either \(\alpha\) or \(\beta\)) strictly determines the structural properties and enzymatic digestibility of the resulting polysaccharide.
Step 2: Key Formula or Approach: The approach involves analyzing the structural molecular bonds of polysaccharides and matching them with the enzymatic capabilities of the human digestive system.
Step 3: Detailed Explanation: Cellulose is a highly rigid structural polysaccharide found predominantly in plant cell walls.
It consists of a long, linear chain of D-glucose molecules linked together by \(\beta\)-1,4 glycosidic bonds.
Human digestive enzymes, such as salivary amylase and pancreatic amylase, are structurally specific for recognizing and breaking down \(\alpha\)-1,4 glycosidic linkages (which are found in starch and glycogen).
Humans completely lack the enzyme cellulase, which is required to hydrolyze the \(\beta\)-1,4 linkages.
Consequently, cellulose passes through the human digestive tract completely undigested and serves a vital role as dietary roughage or fiber.
Step 4: Final Answer: The specific presence of the \(\beta\)-1,4 glycosidic linkage renders cellulose indigestible by human digestive enzymes.