Dear whizwoman-ga;
I hope that you were not expecting to receive a cut-and-dried answer
to your question. Actually, the commonality among the various forms of
bacteria (and lo, there are many) is quite complex:
There are many types of bacteria known to the world of science. They
come in many shapes and sizes. Some of them are good and play
instrumental roles in our environment, and some are, well, relatively
nasty little organisms. The logical assumption is that there are also
unknown varieties, thus was born the need for a means of
identification.
Classifying bacteria on the basis of their morphology (ability to
change and/or adapt to their environment) is extremely difficult, yet
possible. As one might imagine, bacteria are very small, even in
comparison to other organisms, and generally have simple shapes (with
the exception of some bacteria, notably the cyanobacteria – a form of
blue green algea, and actinomycetes – a thread like bacteria found in
the soil, which have very complex shapes). In addition to shape,
bacteria have traditionally been identified and classified on the
basis of their biochemistry and the conditions under which they grow.
Furthermore, today’s advances in molecular biology now permits
scientists to classify bacteria on the basis of similarities among DNA
sequences; a feat that was unimaginable only a few years ago. This
type of routine classification has changed the way that science
approaches bacterial systematics.
According to Edward Richter, Faculty, Food Microbiology, Ohio State
University, “It is not possible to indentify bacteria by just looking
at the colony on a petri dish. However, experience and the use of both
selective and differential media allows microbiologists to both detect
and identify bacteria.”
In order to find the common characteristics among bacteria one must
look to the identification process itself. Cells are routinely
identified and classified as being bacteria based on (1) their shape,
(2) their morphology, (3) their reaction to their environment and,
most recently, (4) their DNA sequence.
“Systematics of Bacteria”
http://www.ucmp.berkeley.edu/bacteria/bacteriasy.html
“MadSci Network”
http://www.madsci.org/posts/archives/mar99/921863100.Mi.r.html
I hope this answers your question.
Best regards;
Tutuzdad-ga |
