Download Microbiology : Unit #2 : Bacteria

Bacteria
 Bacteria are small living
organisms found almost
everywhere on the earth.
 Bacteria are prokaryotes
which are typically
unicellular.
*There are more bacteria
living in your mouth than
there are people living on
Earth!
Classification of Bacteria
 Bacteria are classified
into two major
Kingdoms :
Archaebacteria and
Eubacteria.
 Archaebacteria : live
without oxygen, and
obtain their energy
from inorganic
compounds.
Archaebacteria
 Archaebacteria can survive
and thrive in “harsh”
environments.
 Examples of archaebacteria
include : methaneproducting bacteria in cows
stomachs, salt-loving
bacteria, and heat and acid
loving bacteria which
thrive in hot springs.
Archaebacteria
 Archaebacteria found in
the stomachs of cows allow
for the cow to break down
and digest the “cellulose”
in plant cells. These
bacteria help cows turn
cellulose into glucose. The
bacteria produce methane
gas in this process.
Eubacteria
 Eubacteria differ from
Archaebacteria in
differences of cell
walls, plasma
membrane, and
sequence of DNA
bases.
Eubacteria
 Most common bacteria are
classified as eubacteria.
 Eubacteria include the
phostosynthetic bacteria
called cyanobacteria.
Bacteria Structure
Bacteria have different shapes and structures, but
structures found in bacteria include :
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Flagella (some)
Capsule (some)
Cell wall
Plasma membrane
DNA
Pili (some)
Bacteria Shapes
Most bacteria are found
in “colonies”.
 Bacteria can be round,
spiral, or rod shaped.
 Round : coccus
 Spiral : spirillum
 Rod : bacillus
Bacteria are also classified
into the shape of groups or
colonies they form.
• Diplo : paired cells
• Staphylo: grapelike clusters
• Strepto: long chains
Bacteria Reproduce by:
Conjugation (Sexual)
Binary Fission
In conjugation one bacteria
(Asexual)
is able to transfer its DNA
into another bacteria by
means of a pilus (pili)
Binary fission involves
the copying of the
DNA and the splitting
into two new cells.
Bacteria Reproduction
 Under optimum
conditions bacteria can
reproduce every 20
minutes.
 Bacteria reproduction
is controlled by various
factors including :
temperature and food
availability.
Bacteria- Cell Wall Structure
 Bacteria are divided into
two groups based upon the
composition of their cell
walls.
 Gram positive : two layers
( lipid, peptidoglycan –
sugar/amino acids
network)
 Gram negative : three
layers, lipid,
peptidoglycan, and
lipopolysaccharide.
Gram +
Gram -
Antibiotics
 Most antibiotics aim to
break down part of the
cell wall to cause water
to move in and rupture
the bacteria cell.
 Penicillin is one
bacteria to work this
way.
Bacteria
 One major role of bacteria
in the envrironment is to
“fix” nitrogen from the
atmosphere into a useable
form for plants.
Rhizobium bacteria live on legume roots.
Bacteria - Decomposers
 Bacteria break down
organic matter in dead
organisms.
 These heterotrophic
bacteria help recycle
nutrients from dead
plants and animals
back into the soil.
Bacteria help break down leaves into
useable compounds in the soil.
Bacteria
 Bacteria also are used to
make antibiotics. Some
helpful bacteria will
produce chemicals which
will kill pathogenic
bacteria.
 Streptomycin and
erythromycin are a few
examples of antibiotics
made from bacteria.
Bacteria Caused Diseases
 Bacteria can cause the
following diseases:
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Tuberculosis
Pneumonia
Strep throat
Staph infections
Scarlet fever
Syphilis
Gonorrhea
Chlamydia
Boils
Tetanus
Lyme disease
Ear infections
Bacteria and Disease
 Bubonic Plague/Black
Death.
 In the 1330’s the bubonic
plague originated in China.
This disease caused by
bacteria spread quickly to
England and other parts of
present day Europe.
 This bacteria was mainly
found on rodents but fleas
are thought to have carried
it to humans.
Bubonic Plague
 The bubonic plague killed
an estimated 1/3rd of all
Europeans.
 The bacteria caused boils
which started as red bumbs
on the skin, and then
turned into black dots.
“Black Death”.
 The bacteria Yersinia
pestis is thought to have
caused this disease.
Exit Slip
1. What is the name of this bacteria?
2. What is the name of this
bacteria?
3. Draw a staphylobacillus
bacterial colony.