Name Bacteria and Viruses
Bacteria: Size, Shape, and Reproduction
Bacteria are a kind of microorganism that consist of only a
single cell. Bacteria sometimes group together in pairs,
chains, or clusters.
Bacteria are prokaryotic, which means that they don’t
have a nucleus. Unlike eukaryotic cells, which do have a
nucleus, bacteria have a cell wall. Different kinds of
bacteria have different kinds of cell walls, which makes it
easier for scientists to tell different kinds of bacteria apart.
Bacteria come in all kinds of shapes and sizes, but they can generally be
grouped according to whether or not they most resemble a rod, a sphere,
or a curve. The five classifications of bacteria within those categories are:
spherical (cocci), rod (bacilli), spiral (spirilla), comma (vibrios) and
corkscrew (spirochaetes).
Bacteria reproduce using a process called binary fission, which means
that a single bacteria cell splits itself into two identical daughter cells. First,
the bacterium’s DNA makes a copy of itself. The cell then grows longer
and splits into two cells, each of which contain a strand of DNA identical
to that of the parent cell. These daughter cells are actually clones of the
original cell.
Some bacteria reproduce very quickly. Under the right conditions, at the
right temperature and with proper nutrients available, some bacteria can
divide every 20 minutes. At this rate, one bacterium can produce over
two million copies of itself in just seven hours. Within another hour, it can
have made a total of over 16 million copies. Some bacteria make us very
sick very fast because bacteria can colonize the human body so quickly.
Bacteria can be hard to kill because of their ability to go dormant by
forming endospores. In this dormant state, they are very resistant to being
destroyed by heat, UV radiation, and disinfectant.
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