Multiple Choice
Which of the following is a digestible, straight-chain type of starch composed of glucose units?
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1. Introduction to Biochemistry
Carbohydrates
Multiple Choice
Which of the following best describes the primary structural difference between cellulose and starch?
A
Cellulose is composed of β(1→4) glycosidic bonds, while starch is composed mainly of α(1→4) glycosidic bonds.
B
Cellulose is soluble in water, while starch is completely insoluble.
C
Cellulose contains only fructose units, while starch contains only glucose units.
D
Cellulose is a branched polymer, whereas starch is a linear polymer.
Verified step by step guidance1
Step 1: Begin by understanding the structural composition of cellulose and starch. Both are polysaccharides made up of glucose units, but their glycosidic bond types differ significantly.
Step 2: Cellulose is composed of β(1→4) glycosidic bonds, which link glucose molecules in a linear fashion. These bonds result in a rigid structure that is insoluble in water and provides structural support in plant cell walls.
Step 3: Starch, on the other hand, is primarily composed of α(1→4) glycosidic bonds. These bonds create a structure that is less rigid and more accessible for enzymatic breakdown, making starch a storage polysaccharide in plants.
Step 4: Analyze the options provided in the question. The correct answer should highlight the difference in glycosidic bond types: β(1→4) for cellulose and α(1→4) for starch. Other options, such as solubility, sugar units, or branching, are incorrect based on the biochemical properties of these molecules.
Step 5: Conclude that the primary structural difference between cellulose and starch is the type of glycosidic bond: β(1→4) in cellulose versus α(1→4) in starch. This distinction is crucial for their respective biological roles and physical properties.
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