A) Why study microorganisms? They affect our lives
directly and indirectly; in beneficial ways and in detrimental ways.
1) Cause disease
a)
Viruses - flu (influenza virus) ; bacteria - Strep throat (Streptococcus
pyogenes);
fungi - Valley Fever (Coccidiodes immitis) .
2) Important in our environment
- nutrient cycling, for example.
3) Useful - food and beverage,
biotechnology and other industries.
a) bread making, antibiotics, biotechnology.
B) How and when were microorganisms discovered? Who did it?
1) Our first micrscopic view of life
was in 1665 when Robert Hooke observed the surface of cut cork using a
light microscope. He saw spaces in the pattern that he called ěcellsî,
forming the foundation for the Cell Theory of Life,
developed later by Schleiden and Schwann (1840s).
a) Cell Theory - all organisms made up of cells.
2) Antony van Leeuwenhoek in 1673 was
probably the first person to observe microorganisms.
a) He
built magnifying glasses and simple microscopes as a hobby
b) Microscopes
were made of single, biconvex lenses mounted onto metal plates.
Capable of magnifying images up to 300X.
c) With
these microscopes, he observed rain, pond and sea water, as well as infusions
of pepper, and various spices.
d) He
submitted his drawings and observations to the Royal Society of London
and in this way,
his microscopic world became well known.
e) He
observed three common shapes of bacteria, rods, spheres and spirals.
He even observed that the number of little animals decreased after drinking
hot coffee or rinsing
his mouth with vinegar.
C) People began to wonder about the origins of these microbes.
The theory of Spontaneous Generation of Life
had just been disproven by Francesco Redi in 1668.
1) Theory of Spontaneous Generation
- living organisms can arise from non-living matter.
a)
Rediís experiments -
b)
Many people in many countries and labs spent the next 200 years trying
to again disprove
the Theory of Spontaneous Generation.
2) Biogenesis - idea that living
cells arise from preexisting living cells.
D) Spontaneous Generation was finally disproved in the late 1861
when Pasteurís expts were critical in putting this idea to rest.
1) Louis Pasteurës
contributions provided definative results -
2) Thus, began the
Golden Age of Microbiology.
III) Branches of Microbiology - most of which we will cover in
this class.
A) Bacteriology - study of bacteria.
B) Mycology - study of fungi.
C) Parasitology - study of protozoa and parasitic worms (not
really covered in class)
D) Immunology - study of immunity to disease.
E) Virology - study of viruses
F) Microbial Genetics - study of how microbes inherit traits,
like antibiotic resistance.
IV) Classification and naming of Microbes.
A) Five Kingdoms - Monera (Bacteria - Eubacteria, Archaebacteria);
Protista (protozoa, algae);
Fungi (yeasts, molds, mushrooms); Plantae (plants);
Animalia (Animals) .
B) Nomenclature
1) Like other biological names,
we use the binomial system - two names - developed by
Linnaeus in 1753; latin.
a) genus
- always capitalized.
b) specific
epithet or species name - lower case.
The whole name is italicized or underlined.
IV) Two basic cell types found in biological systems - Prokaryotic
and Eukaryotic
A) Prokaryotic - pre-nucleus
1) Simplest
cell type; no internal compartmentalization (no membrane-bound organelles),
no nucleus.
2) All
bacteria are prokaryotic - prokaryotes.
3) Bacteria
are divided into two groups - Archaebacteria and Eubacteria
a) Archaebacteria are ancient bacteria
b) Eubacteria are true bacteria
B) Eukaryotic - true nucleus
1)
More complex cell type; nuclear material surrounded by a membrane, other
membrane-bound
compartments called organelles (i.e. mitochondria, chloroplasts etc)
2) Algae,
fungi, protozoans are all eukaryotic microorganisms.
3) Cells
in all other multicellular organisms, like us, are eukaryotic.
C) Viruses are not prokaryotic or eukaryotic
1) Viruses are
not cellular; they parasites on living cells because they require cellular
machinery to replicate.