Download BACTERIA

The virus
“For about 100 years, the scientific community has
repeatedly changed its collective mind over what viruses
are. First seen as poisons, then as life-forms, then biological
chemicals, viruses today are thought of as being in a gray
area between living and nonliving: they cannot replicate on
their own but can do so in truly living cells and can also
affect the behavior of their hosts profoundly. The
categorization of viruses as nonliving during much of the
modern era of biological science has had an unintended
consequence: it has led most researchers to ignore viruses
in the study of evolution. Finally, however, scientists are
beginning to appreciate viruses as fundamental players in
the history of life.”
What is a virus???
Particles of nucleic acid, proteins, and
in some cases, lipids
Reproduce only by infecting other cells
Vary widely in size and structure
BACTERIOPHAGE
The Common Cold Virus
HIV
Virus “life” cycle
retroviruses
All viruses enter living
cells and, once inside, use
the machinery of the
infecte cell to produce
more viruses
How a Virus Invades Your Body
BACTERIA
microscopic life that covers
nearly every square centimeter of
the Earth yet was completely
unknown until the invention of
the
microscope
“
What are bacteria???
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Prokaryotic cells- which means what exactly?
Smallest and most common microorganism
Range in size from 1 to 5 micrometers (unless
you are a Epulopiscium fisheloni in which
case you are much larger)
Often thought of as bad guys but really not so
much
Classification of bacteria
Eubacteria
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Largest group, quite varied
Find living almost everywhere
Cell wall made of a carbohydrate called “Peptidoglycan”
The cell wall:
1. protects from injury
2. determines shape of bacteria
ARCHAEBACTERIA
• Cell wall lacks peptidoglycans
• DNA sequences more similar to that
of Eukaryotes suggesting they may
be the early ancestors of eukaryotic
organisms
• Able to live in very harsh
environments such as salt water and
hot springs.
• Methanogens live in oxygen-free
environments such as thick mud
and intestines of animals
methane gas
We can identify bacteria
by their :
1. Shape
a. Cocci
b. Bacilli
c. Spirilli
2. Nature of Cell Wall
GRAM + (with peptidoglycan)
GRAM - (without peptidoglycan)
3. Movement- if and how
flagella
or slime
Flagellar Motion
Bacteria can be
heterotophic or
autotrophic when they eat.
Bacteria can be aerobic and
carry out respiration,
anaerobic causing
fermentation or a
Bit of both- facultative
Bacteria make more
bacteria through:
Binary Fission
b.f.
Spore Formation
Conjugation
Significance of bacteria
1.
2.
3.
4.
5.
6.
7.
8.
Capture energy through photosynthesis
Decomposers
Nitrogen-fixers
Produce food and beverages
“Eat” small oil spills
Purify H2O
Synthesize drugs, chemicals
Produce vitamins in human gut
And sometimes they make
us sick…
Pathogens
120,000 to 150,000
different species of
bacteria are thought to
exist.
But less than 1% of
these make us sick
Antibiotic
resistance