Multiple Choice
Why is it that RNA can catalyze reactions but DNA cannot?
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6. Enzymes and Enzyme Kinetics
Enzymes
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What is the primary function of the enzyme lactase?
A
It converts sucrose into glucose and fructose.
B
It synthesizes lactose from glucose and galactose.
C
It catalyzes the hydrolysis of lactose into glucose and galactose.
D
It breaks down starch into maltose.
Verified step by step guidance1
Understand the role of enzymes: Enzymes are biological catalysts that speed up chemical reactions without being consumed in the process. Lactase is an enzyme specifically involved in carbohydrate metabolism.
Identify the substrate of lactase: Lactase acts on lactose, which is a disaccharide composed of glucose and galactose. Lactose is commonly found in milk and dairy products.
Determine the reaction catalyzed by lactase: Lactase catalyzes the hydrolysis of lactose, breaking the glycosidic bond between glucose and galactose. This reaction requires water and results in the formation of two monosaccharides: glucose and galactose.
Clarify the incorrect options: Lactase does not act on sucrose (which is broken down by sucrase into glucose and fructose), nor does it synthesize lactose from glucose and galactose. Additionally, lactase does not break down starch into maltose; this is the function of amylase.
Conclude the primary function: The correct answer is that lactase catalyzes the hydrolysis of lactose into glucose and galactose, enabling the digestion of lactose in the human body.
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