Problem 7 - A Guide to the Principles of Animal Nutrition

Question

A structural homopolysaccharide made of glucose is a. cellulose b. hemicellulose c. pectin d. raffinose

Step-by-Step Solution

Answer

The answer is (a) cellulose.

Step 1: Identify the Compounds

Review the list of options provided: cellulose, hemicellulose, pectin, and raffinose. These are different types of carbohydrates.

Step 2: Understand Structural Homopolysaccharide

A structural homopolysaccharide is made up of many repeating units of a single type of sugar molecule and is part of the structural framework in plants. Glucose is a common sugar unit in these structures.

Step 3: Match Compound to Definition

Determine which option is a structural homopolysaccharide made of glucose. Cellulose is a well-known structural homopolysaccharide composed of glucose molecules linked together, making up the cell walls of plants.

Step 4: Confirm Answer Using Process of Elimination

Check other options: hemicellulose is a heteropolysaccharide (not only glucose), pectin is primarily a heteropolysaccharide rich in galacturonic acid, and raffinose is a trisaccharide, not a polysaccharide.

Key Concepts

Structural Homopolysaccharide

A structural homopolysaccharide is a type of carbohydrate made up of repeated units of a single sugar molecule. In the context of cellulose, these repeating units are glucose molecules. This structural feature is crucial because it forms a strong, fibrous support material within plant cells.
Homopolysaccharides like cellulose are essential for plant rigidity.
They form elongated chains that entangle and create a tough, resistant structure.

• The long chains align parallel to one another.
• They connect through hydrogen bonds, adding strength.
• This arrangement is highly durable and resists breakdown.

These features make cellulose an immensely important structural component, differing significantly from other polysaccharides that may serve energy or storage purposes.

Glucose Polysaccharide

Glucose polysaccharides are carbohydrates formed by polymerizing glucose, one of the most common monosaccharides. When glucose units link together, they form polysaccharides, giving them various structural or storage roles, depending on how they are linked.
In the case of cellulose, the linkage between glucose molecules is through beta-1,4-glycosidic bonds.

• This bond type contributes to cellulose's robust and stiff nature.
• It prevents easy digestion in many animals, as specific enzymes are needed to break these bonds.

Cellulose, a notable glucose polysaccharide, is fundamental in plant structures.
It serves not only as a support framework but also is less prone to enzymatic degradation, thus protecting plant cells.

Plant Cell Wall

The plant cell wall is a defining feature of plant cells, providing them with structural integrity and protection. This wall is primarily composed of cellulose, which is responsible for its strength and rigidity.
The plant cell wall supports various functions:

• Keeping the cell shape consistent.
• Preventing excessive water influx by maintaining osmotic balance.
• Providing a barrier against pathogens.

Moreover, the cellulose fibers in the cell wall are interwoven with other polysaccharides and proteins, forming a complex matrix. This matrix is key to the plant's ability to withstand external stresses and maintain internal stability.
Cellulose's role in the plant cell wall highlights its importance as a structural homopolysaccharide made of glucose, reaffirming its critical role in nature.