Transcript File
Microbes like bacteria
and viruses are part of
our daily lives!
Summary color is red;
underlined words are
vocabulary; hyperlinks
in blue.
 In 2009 the world was introduced
to swine flu (H1N1) which is caused
by new strain of virus similar to the
common cold; it quickly spread
around the globe.
 Tuberculosis, TB (shown here) hit
Houston in 2013!
 Microscopic life is everywhere, but
not all microbes are deadly!
 The smallest and most
common living
microorganisms are
prokaryotes (lack a nucleus
and organelles).
 Unicellular (one cell)
 Circular DNA called
 Some have pili and/or
"Typical blue-green alga and bacterial cells." The Gale
Encyclopedia of Science. Ed. K. Lee Lerner and Brenda
Wilmoth Lerner. 4th ed. Detroit: Gale, 2008. Science in
Context. Web. 14 Mar. 2014.
Electron micrograph of
Martian meteorite
ALH84001 showing
structures that some
scientists think could be
fossilized bacteria like
life forms. Image
 Bacteria comes in many shapes [the colors match the
 Spheres (or cocci)
 Rods (or bacilli)
 Spirals (or spirilla)
 Chains (or strepto)
 Clusters/Groups (or staphlyo)
Colored scanning, electron micrograph (SEM) of anthrax
bacteria (Bacillus anthracis), the cause of the disease
anthrax in humans and livestock. Anthrax is used as in
 Bacteria reproduce
in three ways:
1. Binary fission asexual
reproduction, cell
divides producing
2 identical
daughter cells
 Video
2. Conjugation - sexual
reproduction that
exchanges genetic
material between 2 cells
▪ Moves DNA between
cells, allows for
genetic diversity
▪ Bacterial cells can
mutate to create new
▪ Animation
An endospore. Bacillus anthracis, the
bacterium that causes anthrax, produces
persistent endospores. The thick,
protective coat helps it survive in the soil
for years. Image
3. Spores – some bacteria
delayed reproduction,
thick walls around their
DNA called an
endospore during
unfavorable conditions;
they can resist drought,
heat, even radiation.
 When conditions
improve, the
endospore and the
bacteria grows again.
 Foods! EX cheese, yogurt ,
soy sauce, etc.
 Some bacteria can remove
waste products from water
and sewage; bacteria has
been modified to consume oil
in oil spills.
 Bioremediation – process
of using microorganisms to
help restore natural
environmental conditions.
 Some bacteria are producers and create oxygen and/or
nitrogen used by some plants and animals.
 As decomposers, they help to recycle nutrients into raw
 A virus is an infectious agent with
a core of genetic material (DNA
or RNA) and surrounded by a
protein coat [capsid] and lipid
 They are NOT cells
 (no membranes or organelles)
 Reproduce only within a host
 Considered parasites
 Animation
 This diagram compares a human liver cell, a single
ribosome, and a bacterium, to some common viruses.
 Viruses are very very small (b/w .003 ~ .05 microns)!
 Viruses come in many
 Viral shapes include:
 Helical a twisted coil
 Polyhedral a sphere
surrounded by
polygons; EX Herpes
 Spherical EX
 And others
 Viruses are very host
specific; the protein
arrangement [coding
spikes] on the exterior
recognize certain types
of cells [like the lock
and key model in
 A virus needs a host to
reproduce; they have to
use a cell!
 A host is an organism
that shelters and
nourishes something
else (think hostess).
 Viruses reproduce in
three ways:
 Lytic
 Lysogenic
 Retrovirus
 Lytic Cycle – viral
replication that rapidly kills
a host cell
1. Virus attaches to cell and
injects its genetic material
2. Tricks the host cell to
make viral mRNA
3. Chops up [using enzymes]
the cell’s DNA; assembles
viral DNA
4. The cell now builds viruses
5. Cell lyses, or bursts
6. Minion viruses infect
other cells
 Lysogenic Cycle – the virus does
not immediately kill the host cell
[remains dormant] EX Herpes
 Viral genome inserts itself into
the hosts DNA [provirus]
 Every time the cell divides, the
“invading” virus’ DNA is
 Eventually, the virus is
activated and enters the lytic
 The most complicated form of viral replication is the
retrovirus; prefix retro means backwards from RNA to
 They produce a copy of DNA using reverse
transcriptase, an enzyme then
 Then follows the steps of lysogenic replication
 Some bacteria and viruses [and other types of life] can be
pathogens; some pathogens are deadly, some are not.
 Epidemiologists are scientists who study the cause and
spread of diseases [pathogens] through populations.
 By doing this, scientists help prevent or control the spread
of diseases; use this interactive to learn about common
A nefarious baculovirus,
that only targets the
gypsy moth caterpillar,
infects it's host and forces
it to climb to the very top
of a tree, before liquefying
it and showering deadly,
disease-ridden goo down
onto the other caterpillars
below. Horror horror
From Sinister Virus Image
Zombie Caterpillars Video
Potato spindle tuber viroid
(PSTVd) in tomatoe plants. Image
 Viroids cause disease in plants
 Just a single strand of RNA molecule w/ no capsid
 Prions cause disease in animals
 Just particles of protein
 EX Mad cow disease and Creutzfeldt-Jakob disease may
be caused by prions.
 Vaccines - stimulate the
body’s immune system
with antigens to prevent
 Antibiotics - block the
growth of bacteria
 They can be used to
cure and treat many
diseases caused by
bacteria that, in the
past, have been deadly.
 Vaccines - stimulate
the body’s immune
system with a
harmless (weakened
or dead) form of a
virus to create
antigens to prevent
 EX Flu shot,
chicken pox
 Animation
 Modern bacteria have evolved!
 Disinfectants, antiseptics, hand
sanitizers and anti-bacterial
soaps are designed to kill
 Remember, however, the overuse
of these products and antibiotics
can cause the bacteria to mutate
and become resistant and more
dangerous and difficult to kill.
 Super Germs Video