Bacteria
Facts:
1) Microscopic life covers nearly
every square centimeter of the
earth!
2) The smallest and most common
microorganisms are
prokaryotes.
3) Prokaryotes are otherwise
known as bacteria.
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Bacteria Structures
Key structural
features:
1)Cell Wall with
or without
peptidoglycan
2)Cell membrane
3)DNA not
contained in a
nucleus
4)Pili
5)Ribosomes
6)Flagellum
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Classifying Prokaryotes
•Bacteria used to be
placed into one kingdom
called Monera.
•Recently, they have been
divided into two kingdoms:
1) Eubacteria
2) Archaebacteria
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Eubacteria
• common bacteria that
live in fresh and salt
water, on land and in
the human body.
• Have cell walls that
contain peptidoglycan
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Eubacteria
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Archaebacteria:
 Found in harsh
environments
 Undersea volcanic vents,
acidic hot springs, salty
water
 Lack peptidoglycan
 Contain DNA sequences
that are more similar to
eukaryotes than
eubacteria.
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Archaebacteria
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Identifying Prokaryotes
4 ways prokaryotes are identified:
1) Shape
2) Cell wall composition
3) Movement
4)
The way they obtain and
release energy- metabolic
diversity
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Shape
3 Common Prokaryote
shapes:
1) Bacilli- rod shaped
2) Cocci- spherical
shaped
3) Spirilla- spiral or
corkscrew shaped
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Grouping of Bacteria
• Diplo- Groups of
two
• Strepto- chains
• Staphylo- Grapelike
clusters
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On your whiteboard:
1)What would a chain
of round bacteria be
called?
2)What would a
cluster of rodshaped bacteria be
called?
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Diplococcus
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Streptococcus Causes
Strep Throat
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Staphylococcus
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Cell Wall Composition
Gram Positive= peptidoglycan
present
Gram negative= no
peptidoglycan present
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On your whiteboard:
In what kingdom
would a grampositive bacteria cell
fit?
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Movement
4 ways prokaryotes move:
1) Flagella
2) Lash, snake, or spiral
3) Glide on secretions
4) Some don’t move at all
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Metabolic Diversity:
Obtaining Energy
Heterotrophs (2 types):
1) Chemoheterotrophs
Take in organic molecules for:
•
• Energy
A supply of carbon
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2) Photoheterotrophs
• Photosynthetic
•
But need to take in
organic compounds as a
carbon source.
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Autotrophs (2 types):
1) Photoautotrophs
•
• Photosynthetic
Live where light is plentiful
like the surface of lakes,
streams, and oceans.
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2) Chemoautotrophs
• Also make organic
molecules from CO2 but do
not need light to do it.
•
Live deep in the ocean
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Metabolic Diversity:
Releasing Energy
3 types of Prokaryotes
1) Obligate Aerobes- require a
constant supply of oxygen, use
cellular respiration
2) Obligate Anaerobes- do not
require oxygen, use
fermentation
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3) Facultative Anaerobescan survive with or without
oxygen, can switch back
and forth between cellular
respiration and
fermentation. Ex- E.coli
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On your whiteboard:
Bacteria
Obtaining
Energy
Releasing
Energy
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Create a Concept Map
of Bacteria Metabolic
Diversity:
Obtaining
Energy
Releasing
Energy
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On your whiteboard:
List the four ways to
identify a prokaryote
from today’s notes.
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Growth and Reproduction
• Bacteria reproduce asexually
by binary fission
• Single chromosome
replicates & then cell divides
• Rapid
• All new cells identical
(clones)
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Cellular organism copies it’s genetic information
then splits into two identical daughter cells
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Binary Fission E. coli
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• Bacteria increase
genetic diversity
through conjugation.
• Hollow bridge (pili)
forms between bacteria
cells.
• Genes move from one
cell to the other.
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Pili in Conjugation
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• When the growing
conditions become
unfavorable, bacteria cells
form spores.
• Example- endospore: the
bacteria produces a thick
wall around its DNA.
• The wall protects the DNA
in harsh conditions until
conditions improve.
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Importance of Bacteria
• Bacteria can be:
1) Decomposers
2) Nitrogen fixers
3) Used by humans
Bacteria are vital to
the living world!
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Decomposers
• Bacteria “recycle” the
nutrients left by things
that die.
Example: Decomposition of a
dead tree.
• Bacteria breakdown sewage
into usable resources.
Example: purified water,
fertilizers
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Nitrogen Fixers
• Plants cannot use nitrogen
from the atmosphere
directly.
• Bacteria use nitrogen
fixation to convert
nitrogen into a usable form
for plants.
Example: soybean plants
have nitrogen fixers in
their roots.
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Human Uses
• Uses for bacteria include
making food like yogurt
and cheese.
• Some bacteria can digest
oil making them helpful in
cleaning up oil spills.
• They can help make drugs
and chemicals.
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Human Uses
• A symbiotic relationship
exists in our own
intestines!
• We provide: warmth,
safety, food,
transportation
• The bacteria provides:
vitamins we do not
naturally make.
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E. coli
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