Microorganisms, such as bacteria, viruses,
and fungi can do many harmful things to our
bodies. Any organism that invades the body of a
host and causes harm in order to survive is
called a “pathogen”. Some pathogens actually
enter cells and cause damage while others remain
outside our cells, and use special proteins to
insert toxins into our body’s cells.
An example of an organism that can enter the
cell and damage your organelles is Salmonella.
This bacterium is the most common cause of food
poisoning. If anyone has ever warned you not to
each a raw egg or raw chicken, it is because
there is a chance it is contaminated with this
bacterium, and will get you very sick.
Salmonella are engulfed by your body’s
macrophage cells. The job of these cells is to
find invading organisms, engulf them, and kill
them. Typically, the macrophage will engulf an
organism into a compartment called
the “phagosome”, which then fuses with an
organelle called the lysosome. The job of the
lysosome is to break down debris with acid.
Salmonella, however, have evolved to escape
being killed in the lysosome by secreting
proteins that prevent the phagosome from fusing
with the lysosome. This protects the
Salmonella, which are also able to secrete
proteins that alter the phagosome to make it a
favorable environment for Salmonella to live
in. Not only does Salmonella prevent the
phagosome from fusing with the lysosome, but
they prevent normal trafficking of cellular
debris to this compartment. The tuberculosis
bacterium also survives in the cell in a similar
way, preventing fusion of the phagosome with the
lysosome and altering transport of cellular
debris to the lysosome.
Salmonella and Chlamydia trachomatis (the
bacterium that causes the STI Chlamydia) can
also affect formation and function of
microtubules. Microtubules are important in
both providing structure to our cells as well as
allowing transport of proteins and lipids
throughout the cell. Without this transport
system, our cells would not be able to form
organelles, such as the golgi apparatus, which
are made of complex lipid membranes. Disruption
of microtubule formation has a widespread affect
on the structure and repair of many organelles
within the cell.
These invading organisms do not necessarily
target our body’s organelles directly. They try
to manipulate parts of the cell to aid in their
own survival, which typically has negative
consequences for our organelles and cells.
Hope that helped! Let me know if you have