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Ch. 5 - An Introduction to Carbohydrates
Freeman - Biological Science 8th Edition
Freeman8th EditionBiological ScienceISBN: 9780138276263Not the one you use?Change textbook
All textbooksFreeman 8th EditionCh. 5 - An Introduction to CarbohydratesProblem 8
Chapter 5, Problem 8

Lysozyme, an enzyme found in human saliva, tears, and other secretions, catalyzes the hydrolysis of the β-1,4-glycosidic linkages in peptidoglycan. Predict the effect of this enzyme on bacteria and how it may be involved in human health.

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Understand the role of lysozyme: Lysozyme is an enzyme that catalyzes the hydrolysis of β-1,4-glycosidic linkages in peptidoglycan, which is a major component of bacterial cell walls, particularly in Gram-positive bacteria.
Explore the structure of peptidoglycan: Peptidoglycan is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of most bacteria, providing structural support and protection.
Analyze the effect of lysozyme on bacteria: By breaking down the β-1,4-glycosidic linkages in peptidoglycan, lysozyme weakens the bacterial cell wall, leading to cell lysis and death, especially in Gram-positive bacteria.
Consider the implications for human health: Lysozyme is part of the innate immune system, providing a first line of defense against bacterial infections by targeting and destroying bacteria before they can cause harm.
Reflect on the broader significance: The presence of lysozyme in human secretions like saliva and tears helps protect against bacterial invasion, contributing to overall health and preventing infections.

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Key Concepts

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

Lysozyme Function

Lysozyme is an enzyme that catalyzes the hydrolysis of β-1,4-glycosidic linkages in peptidoglycan, a major component of bacterial cell walls. By breaking these bonds, lysozyme weakens the structural integrity of the bacterial cell wall, leading to cell lysis and death, particularly in Gram-positive bacteria.
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Peptidoglycan Structure

Peptidoglycan is a polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of most bacteria, providing structural support and shape. The β-1,4-glycosidic linkages connect N-acetylglucosamine and N-acetylmuramic acid, which are targeted by lysozyme, compromising the cell wall's strength.
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Role in Human Health

Lysozyme plays a crucial role in human health by serving as a natural defense mechanism against bacterial infections. Found in secretions like saliva and tears, it helps protect mucosal surfaces by breaking down bacterial cell walls, thus preventing the colonization and spread of potentially harmful bacteria.
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Related Practice
Textbook Question

Which of the differences listed here could be found among molecules of the same monosaccharide? Select True or False for each statement.

T/F There is a difference in the orientation of a hydroxyl group in the ring form.

T/F There is a difference in the number of carbons.

T/F There is a difference in the position of the carbonyl group in the linear form.

T/F There is a difference in the overall shape of the molecule—one is a ring and the other is linear.

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Textbook Question

Although cellulose and starch are identical in terms of stored chemical energy, our ability to harvest the energy from these two polysaccharides differs considerably. What is responsible for this difference?

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Textbook Question

Contrast the structure of glycogen and chitin in terms of their monosaccharides, glycosidic linkages, and interactions between polysaccharide chains.

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Textbook Question

Galactosemia is a potentially fatal disease that occurs in humans who lack the enzyme that converts galactose to glucose. If you were a physician treating a person with this disease, which of the following would you have them exclude from their diet?

a. Maltose

b. Starch

c. Mannose

d. Lactose

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Textbook Question

If you hold a salty cracker in your mouth long enough, it will begin to taste sweet. What is responsible for this change in taste?

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