Question

Use the following paragraph to answer the corresponding question.

Masatomo Kawakubo et al. reported in Science in August 2004 that the human stomach contains a natural, carbohydrate-based antibiotic that probably protects a large portion of the population from various diseases caused by the bacterium Helicobacter pylori. This bacterium has been linked to peptic ulcers, gastritis, and stomach cancer. This naturally occurring antibiotic is described by Kawakubo as having a terminal 1,4-linked N-acetylglucosamine (NAG), and it acts by inhibiting the biosynthesis of a major component of the cell wall in H. pylori. [Source: M. Kawakubo et al., Science 305 (2004): 1003.]


Refer to the paragraph about Kawakubo's group. Kawakubo's group created a glycoprotein with a terminal NAG (i.e., a protein with NAG attached to its end). Their hypothesis is that the terminal NAGand not the protein component-is responsible for the damage to the cell wall in H. pylori. What would be the most appropriate control for testing this hypothesis?

Answer 1

To test Kawakubo's group's hypothesis that terminal N-acetylglucosamine (NAG) damages H. pylori cell walls, the suitable control is a similar glycoprotein without the terminal NAG, as well as testing NAG alone to confirm its independent antibacterial activity.

Step-by-step explanation:

Control for Testing the Hypothesis

To evaluate the hypothesis that the terminal N-acetylglucosamine (NAG) is responsible for the damage to the cell wall in Helicobacter pylori, the most appropriate control would be to use a similar glycoprotein without the terminal NAG. This control would help determine if the presence of NAG is indeed what creates the antibiotic effect or if there are other components in the glycoprotein that contribute to the inhibition of cell wall biosynthesis in H. pylori.

Additionally, it would be wise to test NAG in isolation to confirm its antibacterial activity independently of the protein it is attached to.

Given that H. pylori is linked to peptic ulcers, gastritis, and stomach cancer, understanding and verifying the natural antibiotic properties of NAG could lead to significant therapeutic advancements.