Questions 45-59 are based on the following passage.
In her lab at Princeton
45University, molecular biologist, Bonnie Bassler
leans over a collection of petri 46dishes; her face
illuminated by an aquamarine glow. The glow,
caused by a particular 47species, of bacteria
of a phenomenon Bassler has been investigating for years.
Bacteria, the simplest forms of life, have the ability to
communicate with each other.
As a student in graduate school, Bassler became
intrigued with other 48researchers' and their
involving Vibrio 49fischeri;
a luminescent marine bacteria.
Researchers found that these bacteria only begin to glow
once they have formed a group. A series of experiments
revealed that each bacterial cell releases an autoinducer,
a type of chemical signal. A sensory protein 50allowed
other bacteria to "hear" this molecular message.
Once the bacteria have released a high enough
concentration of 51autoinducer, they
begin to glow. This "quorum sensing" enables
the bacteria to coordinate their actions and
perform their specific function.
52On the contrary,
in her own lab,
Bassler found evidence of quorum sensing in a
53related bacterial species called
Vibrio harveyi. She also
discovered that V. harveyi release a second autoinducer,
or AI-2. This AI-2, which Bassler has described as a
chemical "trade language," makes it possible for bacteria
to communicate with other species of bacteria in the
54same neck of the woods.
She found that each of the
species she studied, including ones that live in
humans, releases AI-2.
After her 2002 discovery, Bassler began
using information from her quorum-sensing
studies to understand how virulent strains of
bacteria found in humans 56communicate.
rely on quorum sensing
to spread disease. Bassler is hopeful that her ongoing
studies of AI-2 will enable [un:58]she and her team[/n:58] to disrupt