Download Unit #1 Notes

Introduction
• Microorganisms are, in large part,
responsible for determining the course of
human history.
• The use of modern sanitation facilities,
vaccinations, as well as antibiotics has
dramatically reduced the incidence of
infectious disease.
Microorganisms Discovered
• Anton van Leeuwenhoek discovered
microorganisms over 300 years ago by
viewing water samples through lenses that
magnified objects three hundredfold.
Spontaneous Generation
• The theory of spontaneous generation was
revived with the discovery of the microbial world.
– Differing results from different investigators
have led to the controversy of whether living
organisms could arise from dead organic
matter. This controversy was not resolved
until the 1860’s.
– Pasteur demonstrated that the air is filled with
microorganisms and showed that swannecked flasks containing sterile infusions
could remain sterile indefinitely.
– Tyndall and, independently, Cohn discovered
that heat-resistant forms of bacteria, or
endospore, were present in certain infusions
Medical microbiology – Past
Triumphs
• Between 1875 and 1918, most diseasecausing bacteria were identified.
Medical Microbiology- Future
Challenges
• “New” diseases are appearing. These include
Legionnaires' disease, toxic shock syndrome,
Lyme disease, and AIDS.
• Many diseases that were on the wane are now
increasing in frequency. These include mumps,
whooping cough, diphtheria, and most recently,
tuberculosis.
• Organisms are becoming increasingly resistant
to antibiotics.
Beneficial Applications of
Microbiology – Past and Present
• Human life could not exist without
the activity of microorganisms
• Microorganisms have been used
for centuries for food production.
Biotechnology – New Applications
for Microorganisms
• Microorganisms are now being developed
to produce vaccines, clean up the
environment, and carry out many other
processes designed to make life more
comfortable.
Cell Theory
• Schleiden and Schwann in the mid –
1800’s proposed the cell theory – that cells
are the basic units of life.
Similarity in Function and
Composition of all Cells
• All cells growing independently of other
cells, such as bacteria, have one basic
function – to reproduce. To do this, they
must generate energy and synthesize the
components of living matter.
• All cells are composed of the same
macromolecules, such as nucleic acids
(DNA and RNA) and proteins, which, in
turn, are composed of the same subunits.
Basic Cell Types
• There are two cell types:
– Prokaryotic cells are simple, without membrane
bound internal structures.
– Eukaryotic cells are larger more complex, and have
several internal membrane-bound structures. All
bacteria are prokaryotic; algae, fungi, and protozoa
are eukaryotic.
• A cell type has been found that appears to be
intermediate between prokaryotes and
eukaryotes; it has t true nucleus but no
mitochondria.