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Ch.16 Amino Acids, Proteins, and Enzymes
Timberlake - Chemistry: An Introduction to General, Organic, and Biological Chemistry 13th Edition
Timberlake13th EditionChemistry: An Introduction to General, Organic, and Biological ChemistryISBN: 9780134421353Not the one you use?Change textbook
Chapter 16, Problem 56a

Adults who are lactose intolerant cannot break down the disaccharide in milk products. To help digest dairy food, a product known as Lactaid can be added to milk and the milk then refrigerated for 24 hours.
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a. What enzyme is present in Lactaid, and what is the major class of this enzyme?

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Step 1: Understand the problem. The question is asking about the enzyme present in Lactaid and its major class. Lactaid is a product used to help lactose-intolerant individuals digest dairy products by breaking down lactose, a disaccharide found in milk.
Step 2: Recall the enzyme responsible for breaking down lactose. Lactose is a disaccharide composed of glucose and galactose. The enzyme that catalyzes the hydrolysis of lactose into these monosaccharides is called lactase.
Step 3: Identify the major class of the enzyme. Enzymes are categorized into six major classes based on the type of reaction they catalyze. Lactase catalyzes the hydrolysis of a glycosidic bond in lactose, which places it in the class of hydrolases. Hydrolases are enzymes that catalyze the cleavage of bonds using water.
Step 4: Summarize the findings. The enzyme present in Lactaid is lactase, and its major class is hydrolases.
Step 5: Relate this to the context of lactose intolerance. Lactose-intolerant individuals lack sufficient lactase enzyme in their digestive system, so adding Lactaid (which contains lactase) helps break down lactose in milk products, making them easier to digest.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Lactase

Lactase is the enzyme present in Lactaid, which is responsible for breaking down lactose, the disaccharide found in milk. In individuals who are lactose intolerant, the body does not produce enough lactase, leading to digestive issues when consuming dairy products. By adding lactase to milk, lactose is hydrolyzed into glucose and galactose, making it easier to digest.
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Enzyme Classification

Enzymes are classified into several major categories based on their function, with lactase belonging to the class of hydrolases. Hydrolases are enzymes that catalyze the hydrolysis of chemical bonds, which involves the addition of water to break down larger molecules into smaller ones. This classification is essential for understanding how enzymes like lactase facilitate digestion.
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Lactose Intolerance

Lactose intolerance is a common condition where individuals lack sufficient lactase to digest lactose effectively. This leads to symptoms such as bloating, gas, and diarrhea after consuming dairy products. Understanding lactose intolerance is crucial for recognizing the importance of lactase supplements like Lactaid in aiding those affected by this condition.
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Related Practice
Textbook Question

In humans, the antibiotic amoxicillin (a type of penicillin) is used to treat certain bacterial infections.

c. Is amoxicillin a reversible or irreversible inhibitor?

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Textbook Question

Ethylene glycol (HO—CH2—CH2—OH) is a major component of antifreeze. If ingested, it is first converted to HOOC—CHO (oxoethanoic acid) and then to HOOC—COOH (oxalic acid), which is toxic.

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a. What class of enzyme catalyzes the reactions described?

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Textbook Question

Ethylene glycol (HO—CH2—CH2—OH) is a major component of antifreeze. If ingested, it is first converted to HOOC—CHO (oxoethanoic acid) and then to HOOC—COOH (oxalic acid), which is toxic.

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b. The treatment for the ingestion of ethylene glycol is an intravenous solution of ethanol. How might this help prevent toxic levels of oxalic acid in the body?

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Textbook Question

Adults who are lactose intolerant cannot break down the disaccharide in milk products. To help digest dairy food, a product known as Lactaid can be added to milk and the milk then refrigerated for 24 hours.

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b. What might happen to the enzyme if the Lactaid were stored at 55 °C?

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Textbook Question

Fresh pineapple contains the enzyme bromelain that hydrolyzes peptide bonds in proteins.

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a. The directions for a gelatin (protein) dessert say not to add fresh pineapple. However, canned pineapple where pineapple is heated to high temperatures can be added. Why?

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Textbook Question

Fresh pineapple contains the enzyme bromelain that hydrolyzes peptide bonds in proteins.

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b. Fresh pineapple is used in a marinade to tenderize tough meat. Why?

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