Darryl Gopaul BSc, MBA, PhD - Senior Consultant, Diamed Lab Supplies
All zoological and botanical life forms on Earth have commensals (i.e., microorganisms or "table companions”) that live on and within them. These synergistic groups of microbes, referred to as normal flora, are part of an organism’s healthy makeup.
This normal flora is composed of a variety of microscopic life forms, from familiar bacteria and viruses to organisms less well-known like fungi, parasites, and tiny invertebrates. Some of these microscopic companions intertwine their own survival with that of their host’s, taking what they need and producing by products that benefit the host. Other microorganisms are not as considerate, with their by-products causing illness and disease in their hosts.
Bacteria, in the context of normal flora, are generally well understood. A bacterium has a cell wall, under which is a membrane that allows water and nutrients to enter its cytoplasm.
Within itself, it keeps safe the genetic factors that allow it to grow and replicate.
Viruses, however, do not have cell walls. They are composed simply of genetic material and an attached protein. Unlike bacteria or fungi, a virus cannot replicate by itself, and so is considered to be non-living.
Viruses are 100 times smaller than bacteria and can only be seen using an electron microscope.
Viruses cannot make proteins independently like bacteria and fungi.
Viruses replicate by entering a host cell (e.g., in the lungs or liver) and taking over its manufacturing apparatus to make its virions.
Viruses have their own unique physical shapes that allow them to home into a specific site on a host cell’s surface, almost like a geometrical fit.
Healthy (non-immunocompromised) human immune systems are often able to keep viruses from multiplying, but viruses do not leave the mammalian body; they remain in a latent form
Read the rest of this educational handout here: