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Bacteria and Viruses
Ch. 19
Bacteria: They’re everywhere!
Size of Bacteria
• Coin 1cm in diameter
• Size of bacteria 1-5 micrometers
• 2000-10,000 bacteria lined up
• Penny 1.9 cm: How many bacteria IN A
LINE?
• Quarter 2.5 cm?
DNA arrangement in
Prokaryotes
• What is this circular DNA
called?
• Plasmid
• Prokaryotes do not have
an organized nucleus or
organelles.
Classifying Prokaryotes
• Eubacteria (true bacteria) –cell wall
contains the carbohydrate,
peptidoglycan.
• Archaebacteria (ancient bacteria)- lack
peptidoglycan in cell walls and have
different membrane lipids. The DNA
sequences of key archaebacteria are
more like those of eukaryotes than
eubacteria. They live in harsh
environments.
Identifying Prokaryotes
• Shape
–
–
–
–
–
Rod (bacilli)
Spiril (spirilla)
Circluar (cocci)
Chain (strepto)
Cluster (staphlo)
• Movement - flagella,
slide, non moblie,
swivel
• Cell Walls
– Gram +: thick
peptidoglycan wall
(purple)
– Gram -: thin layer of
peptidoglycan
inside the lipid
bilayer (pink)
Examples of
pathogenic bacteria
Gram + or Gram –
Identify shape
Metabolic Diversity- another way to
classify
• Heterotrophs- can’t make their • Autotrophs- make own food
own food.
– Photoautotrophs- plants
– Chemoheterotrophs- taken in
photosynthesis
organic molecules for both
– Chemoautotrophs- make
energy and a supply of C. US.
organic compounds from
– Photoheterotrophs- use sunlight CO2. H2S vents
for energy, and need to take in
– Which category do most
organic compounds as C
prokaryotes fall under?
source. Ex: purple non-sulfur
bacteria, heliobacteria
Oxygen or no oxygen?
• Which of these test
tubes show bacteria
growing in an
anaerobic
environment?
• Why?
• Which of these show
bacteria living in an
aerobic environment?
• Why?
Releasing Energy
• Obligate aerobes- require oxygen
Ex: TB
• Obligate anaerobes- require no oxygen
Ex: Clostridium botulium
• Facultative anaerobes- do not require
oxygen, but are not killed by its presence.
Ex: E. coli
Which do you
think were the
first type?
Reproduction
• How do bacteria
reproduce?
• Binary Fission
• What type of
reproduction is this?
• asexual
• What is the end result?
• Bacteria that are
identical to the parent.
Other forms of reproduction
• Spore formation• Conjugation- hollow
occurs when growth
bridge forms between
conditions are
two bacterial cells, and
unfavorable. An
genes move from one
endospore is formed
cell to the other.
to protect DNA and
cytoplasm. When
conditions improve,
endospore will
germinate.
Bacteria Importance
• Decomposers
• Nitrogen fixersconvert N into usable
form. Rhizobium,
nodules on roots of
legumes (bean plants)
• Human uses:
– Food, remove waste
products, digestion,
clean up oil spills.
The bacterial cell
• What is the
flagellum used for?
• Movement
• What are the three
shapes of bacteria?
• Cocci, bacillus,
spirillum
Bacteria Environments
• Where do bacteria
live?
• Everywhere, they’re
ubiquitous
• What do we call the
bacteria that live in
cold temperatures?
• psycrophiles
• What do we call the
bacteria that live in
hot temperatures?
• Thermophiles
• Bacteria that live
in very acidic
environments are
called acidophiles.
• What do we call
those bacteria that
live at “normal”
temperatures?
• Mesophiles
Where bacteria grow, where nothing else
can.
• What do we call
bacteria that live in
swamps? What do they
make?
• Methanotrophs make
methane gas.
• What are bacteria called
that live in extreme salt
conditions?
• Halophiles
Viruses
• Particles of nucleic
acid, protein and in
some cases lipids.
• Nucleic acid (DNA
or RNA) surrounded
by protein capsid
that protects the NA.
• Nonliving
Viral Diversity
• DNA or RNA
• Single stranded or double stranded
• Enveloped (animal) or non-enveloped
(plants)
• Temperate or virulant
• Symmetry: isohedral (many facets) or
helical (round)
Viral Infection
• Lytic- virus enters a
cell, makes copies of
itself and causes the
cell to burst.
• Destroys host cell.
• Lysogenic- virus
integrates its DNA
into the DNA of host
cell, and the viral
genetic information
replicated
indefinitely along
with the host cell’s
DNA.
• Prophage- viral DNA
that is embedded in
the host’s DNA.
Retroviruses
• Contain RNA.
• Produce a DNA copy
of their RNA and
insert it into the
DNA of host cell.
• RNA  DNA using
reverse
transcriptase. (RT)
• AIDS
Vector
• Viruses must have a vector or
living host in order to grow
and reproduce.
– Deer tick and Lyme Disease,
mosquito and Malaria
• Viruses are much smaller
than bacteria.
Pathogens
• Viruses or organisms that
causes an infectious
disease.
• Ex: viruses, bacteria,
protists, fungi,
roundworms and
flatworms.
• Bacteria- some produce
toxins
• Virus- chicken pox, cold
• Protists and roundwormsdestroy body tissue by
feeding on and burrowing
into the tissue.
• Fungi- athletes foot,
ringworm
Remembering Invaders
• Antibiotics
– Slow down microbial
reproduction: bacteria, fungi
and protists
• Vaccinations- Edward
Jenner
• Injections of
weakened or killed
microbes to enhance
immunity
– Stimulate development
of memory cells
Viroids and Prions
• Viroids- contain only RNA,
but lack an envelope and
capsid.
• Cause problems in
potatoes, tomatoes, and
fruit trees.
• Prions- proteins that have
the ability to transmit
diseases.
• Protein direct the host to
create abnormal proteins
that can cause serious
neurological disease in
animals and humans.
• Mad Cow Disease
• Alzheimers ?
Bacteria and Viruses Review
• Go to the following link and click on your
book. Go to Ch. 19 and take the Self-test
and review the concepts.
• Ch. 19 Review
• Be a microbe detective.