Day 68 MCAT Practice Question

Passage 2: Prokaryotic Cells

Escherichia coli (E. coli) is a gram-negative, rod-shaped bacterium that is

commonly found in the gut of warm-blooded organisms. While most strains of

E. coli are harmless, some can cause serious food poisoning in humans. In recent

years, researchers have been investigating the use of bacteriophages, specifically

the T4 phage, as a potential treatment for antibiotic-resistant E. coli infections.

The T4 phage is a lytic virus that infects E. coli by attaching to specific receptors

on the bacterial cell surface. Once attached, the phage injects its genetic material

into the host cell, hijacking the cell’s machinery to produce new viral components.

The phage then assembles these components into new viral particles, which are

released when the host cell lyses.

To investigate the effectiveness of T4 phage therapy, researchers have conducted

experiments using E. coli-infected mice. They found that a single dose of T4 phage

was able to significantly reduce the bacterial load in the mice’s intestines within

24 hours. Furthermore, the phage treatment did not appear to have any adverse

effects on the mice’s health.

One of the main advantages of using bacteriophages to treat bacterial infections is

their specificity. Unlike broad-spectrum antibiotics, which can kill both harmful and

beneficial bacteria, phages only target specific bacterial strains. This reduces the

risk of developing antibiotic resistance and helps maintain the diversity of the gut

microbiome.

However, there are still challenges to overcome before phage therapy can be widely

implemented. One concern is the potential for bacteria to develop resistance to

phages, similar to how they develop antibiotic resistance. Researchers are also

working on developing methods to ensure that phages remain stable and effective

during storage and delivery.

Despite these challenges, the use of bacteriophages like T4 in treating antibioticresistant E. coli infections shows promise. As research continues, phage therapy may

become an important tool in combating the growing problem of antibiotic resistance.

Which of the following is a scientific challenge that needs to be addressed

before phage therapy can be widely implemented?

A) The potential for bacteria to develop resistance to phages

B) The high cost of producing and purifying phages

C) The risk of phages causing harmful mutations in human cells

D) The inability of phages to penetrate bacterial biofilms