Download Notes 9-2

Notes 9-2
Bacteria
2 Kingdoms
• Most scientists agree that there are 2
Kingdoms of bacteria
• 1) Archaebacteria (very ancient)
• 2) Eubacteria (“true” bacteria)
The Bacterial Cell
• Prokaryotic (No
nucleus, so
genetic
material and
ribosomes are
floating in
cytoplasm)
• Circular DNA
• Cell walls
• May have
flagella
Discovery
• Discovered in late 1600s by Anton van
Leeuwenhoek using a microscope
Shapes of bacteria
• 3 Shapes: 1) Spirilla are spiral, Bacilli are rodlike, and Cocci are circular
• You can often tell the shape of the bacteria by
its scientific name.
Bacillus Anthracis
• Can you tell the shape of this bacteria by its
name?
It’s shape is bacilli
or rodlike!
This bacteria
causes anthrax!
Streptococcus pyogenes
• Can you tell the shape of this bacteria by its
name?
It’s shape is cocci or
sperical!
This is one of the
bacterias that
cause strep throat!
Living conditions
• Many can survive harsh conditions by growing
protective capsule called endospores inside
• Some are autotrophs, they make their own
food using sunlight or chemicals
• Some are heterotrophs that consume food
such as other living organisms or dead/
decaying matter
• Some need oxygen and some do not, some
will die in presence of oxygen!
Endospore
• Protects DNA until environmental conditions
are right for survival
Reproduction
• Asexually by binary fission
(cell copies its DNA, then
splits into 2 identical cells)
• Sexually by conjugation
(bridge built between 2
bacteria and DNA is
inserted, then divides
asexually by binary fission,
genetically different from
parent cell)
Role in Nature
• Release O2 gas into air we breathe
• Both food production and spoilage
• Environmental recycling (they’re decomposers
like fungi)
• Environmental cleaning
• Some cause diseases, some used to make
medicines
• Found naturally in body and help many processes