Download Bacteria - Mr. Eeds Biology

Bacteria
EUKARYOTES
PROKARYOTES
BACTERIA ARCHAEA
• Bacteria are of immense
importance because of their
rapid growth, reproduction, and
mutation rates, as well as, their
ability to exist under adverse
conditions.
• The oldest fossils known, nearly
3.5 billion years old, are fossils
of bacteria-like organisms.
Classification of Bacteria
• Archaebacteria: extremists
• Eubacteria:
–Heterotrophs
–Photosynthetic autotrophs
–Chemosynthetic autotrophs
Archaebacteria
• Methanogens – Methane
producers – anaerobic
• Halophiles
–Halo = salt
–Philia = love
• Thermophiles
–Thermo = heat
Thermophiles
These are Archaebacteria from hot springs and
other high temperature environments. Some can
grow above the boiling temperature of water.
They are anaerobes, performing anaerobic
respiration.
Thermophiles are interesting because they contain
genes for heat-stable enzymes that may be of
great value in industry and medicine. An
example is taq polymerase, the gene for which
was isolated from a collection of Thermus
aquaticus in a Yellowstone Park hot spring. Taq
polymerase is used to make large numbers of
copies of DNA sequences in a DNA sample. It is
invaluable to medicine, biotechnology, and
biological research. Annual sales of taq
polymerase are roughly half a billion dollars.
Eubacteria
• Heterotrophs
• Photosynthetic autotrophs
• Chemosynthetic autotrophs
Eubacteria - Heterotrophs
• Found everywhere
• Parasites: live off of other
organisms
• Saprobes: live off of dead
organisms or waste (recyclers)
• Live symbiotically in the guts of
animals or elsewhere in the
bodies
Photosynthetic Autotrophs
• Photosynthetic: make their own
food from light
• Cyanobacteria – blue-green
• Slimy stuff in ponds, streams,
moist areas
• Cyanobacteria were the first
organisms to do modern
photosynthesis and they made the
first oxygen in the earth’s
atmosphere
Eubacteria: Chemosynthetic
Autotrophs
• Get energy by breaking down
inorganic substances like
sulfur and nitrogen
• Make nitrogen in the air usable
for plants – nitrogen fixing
bacteria in roots of legumes
(clover, peas & beans)
Most Bacteria reproduce by
one of 3 means:
1. Asexually
–Also known as
binary fission in
which the
chromosome
replicates and
then the cell
divides
–This produces 2
identical cells
2. Sexually
–Also known as conjugation in
which genetic material is
exchanged through cell-to-cell
contact
–This increases the genetic
diversity of bacteria
Sex pilus
1 m
3. Spore Formation
• When living conditions become
unfavorable, some bacteria can
form dehydrated cells known as
endospores
• Endospores have thick walls and
can resist heat, drought and
radiation and thus they can survive
harsh conditions
Endospore
• When
conditions
improve, the
spore will
germinate
and bacteria
will grow
again
HOW ARE BACTERIA
CLASSIFIED?
Structure of Bacteria
• Two parts to Bacteria
Structure:
–Arrangement
–Shape
Arrangement
• Paired: diplo
• Grape-like clusters: staphylo
• Chains: strepto
Shape
• Rod: bacillus
• Spheres: coccus
• Spirals: spirillum
Shapes of Bacteria
Examples
• Streptococcus: chains of spheres
• Staphylospirillum: Grapelike
clusters of spirals
• Streptobacillus: Chains of rods
• The Gram stain, which divides
most clinically significant bacteria
into two main groups, is the first
step in bacterial identification.
• Bacteria stained purple are
Gram + their cell walls have thick
petidoglycan
• Bacteria stained pink are Gram –
their cell walls have thin
peptidoglycan.
The Gram stain has four steps:
• 1. crystal violet, the primary stain:
followed by
• 2. iodine, which acts as a mordant by
forming a crystal violet-iodine complex,
then
• 3. alcohol, which decolorizes, followed by
• 4. safranin, the counterstain.
Is this gram stain positive or negative?
Identify the bacteria.
Is this gram stain positive or negative?
Identify the bacteria.
Other ways to identify Bacteria
• By their Nutrition
–1. Autotroph
–2. Heterotrophs
• Based on Respiration
–1. Aerobes- need oxygen during
respiration
–2. Anaerobes – do not use oxygen
during respiration
• Obligate aerobes - must have O2
• Obligate anaerobes – must live
without O2
• Facultative anaerobes – can
function without but not killed by
oxygen
How large are bacteria?
• There are 106 µmeters in one
meter, and it is these units that
are used to measure the size of
bacteria.
• Typically, bacteria range from
about 1 µm to about 5 µms.
Virus
Comparing
the size of a
virus, a
bacterium,
and an
animal cell
Bacterium
Animal
cell
Animal cell nucleus
0.25 m
Structure of Bacteria
• Bacteria have cell walls made of
peptidoglycan (amino acid &
sugar)
• Bacteria have a circular
chromosome
Movement
• Flagella ~ Tail like structure the
whips around to propel the
bacterium
• Cilia ~ Miniature flagella surround
the cell that help to “swim”
• Non motile ~ Sticky pili like
structures that keep the bacterium
from moving (pilus – singular)
ECOLOGICAL ROLES
1. Bacteria act as decomposers,
which means they break down
dead organic materials
2. They also help recycle carbon,
nitrogen and sulfur and other
chemicals needed by living things
3.Many bacteria live with organisms
of other species in a relationship
called symbiosis
–bacteria in your mouth (bacteria
benefit & you are harmed)
–bacteria in cow intestines
(bacteria benefit & cow benefits)
–E. coli, a bacteria found in
human intestines, helps with the
process of digestion
DISEASES CAUSED BY BACTERIA
• Some bacteria cause diseases in
humans
• Some examples are:
–Tuberculosis, anthrax, lyme
disease, strep throat, cholera
• Antibiotics can kill harmful
bacteria if used properly
Germ Theory of Disease
• Joseph Lister (1827-1912) –
Aseptic Techniques
• Robert Koch (1843-1910) –
Germ Theory
–A specific microorganism
causes a specific disease
HUMAN USES OF BACTERIA
• Bioremediation – use of
microorganisms to help restore
natural environmental conditions;
ex. Sewage treatment plants
• Bacteria are used in the production
of many foods; some examples
are: cheese, yogurt, vinegar,
beverages (beer & wine)
• Bacteria have applications in
medicine; some bacteria have
been genetically engineered to
produce insulin
• Use plasmids – insert other genes
into bacterial DNA