Question:
Fructans are polymers of fructose built upon which one of the following starter units?
Fructans are polymers of fructose built upon which one of the following starter units?
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Every fructan molecule contains a terminal glucose residue, which is a structural remnant of the initial sucrose starter unit used to seed the polymer chain.
Updated On: Jul 31, 2026
- Glucose
- Galactose
- Sucrose
- Trehalose
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The Correct Option is C
Solution and Explanation
Step 1: Understanding the Concept:
Fructans are fructose-based polysaccharides that many plants use as water-soluble storage carbohydrates in place of or in addition to starch.
Step 2: Detailed Explanation:
All fructan polymers are synthesized from a core sucrose molecule, which consists of a glucose molecule linked to a fructose molecule.
During synthesis, the enzyme sucrose:sucrose 1-fructosyltransferase (1-SST) transfers a fructosyl group from one sucrose molecule to another.
This reaction produces a trisaccharide (such as 1-kestose) and releases a free glucose molecule.
The chain is then elongated by other fructosyltransferases that continue adding fructose units to the growing chain.
Because every fructan chain begins with this initial transfer reaction, sucrose acts as the essential starter unit, leaving a single glucose terminal residue at one end of the finished polymer.
Step 3: Final Answer:
Therefore, fructans are built upon a sucrose starter unit, corresponding to option (C).
Fructans are fructose-based polysaccharides that many plants use as water-soluble storage carbohydrates in place of or in addition to starch.
Step 2: Detailed Explanation:
All fructan polymers are synthesized from a core sucrose molecule, which consists of a glucose molecule linked to a fructose molecule.
During synthesis, the enzyme sucrose:sucrose 1-fructosyltransferase (1-SST) transfers a fructosyl group from one sucrose molecule to another.
This reaction produces a trisaccharide (such as 1-kestose) and releases a free glucose molecule.
The chain is then elongated by other fructosyltransferases that continue adding fructose units to the growing chain.
Because every fructan chain begins with this initial transfer reaction, sucrose acts as the essential starter unit, leaving a single glucose terminal residue at one end of the finished polymer.
Step 3: Final Answer:
Therefore, fructans are built upon a sucrose starter unit, corresponding to option (C).
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