Transcript Chapter 18 - Bacteria slides

Chapter 18
Bacteria
Concept Map
Section 191
Bacteria
are classified into the kingdoms of
Eubacteria
Archaebacteria
include a variety of
lifestyles such as
Living in soil
Go to
Section:
Infecting
large
organisms
live in harsh
environments such as
Thick mud
Animal
digestive
tracts
Salty lakes
Hot springs
Bacteria are part of two kingdoms:
 Archaebacteria
 Eubacteria
Eubacteria
 The larger of the two kingdoms
 prokaryotes
 Cell walls contain peptidoglycan
Archaebacteria
 Prokaryotes, although the DNA are
more like those of eukaryotes than
eubacteria
 Cell walls lack peptidoglycan
 Membrane lipids are different than
those of eubacteria
 Many scientists think that
archaebacteria may be the ancestors
of eukaryotes
Archaebacteria (cont.)
 Many archaebacteria live in harsh
environments
 Methanogens – produce methane gas
 Extreme halophiles – salt-loving
archaebacteria
 Thermoacidophiles – live in extremely
acidic environments that have extremely
high temperatures, like hot springs
Identifying Prokaryotes
 Shape
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Bacilli – rod-shaped
Cocci- spherical
Spirilla – spiral and corkscrew shaped
Identifying Prokaryotes (cont.)
 Cell walls
 Two
different types of cell walls in
eubacteria
 The Gram stain is used to tell
them apart
 Gram-positive – stain purple
 Gram-negative – stain red/pink
Identifying Prokaryotes (cont.)
 Movement

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flagella- whip-like structures used for
movement
Other prokaryotes lash, snake, or spiral
forward
Some other prokaryotes glide slowly along
slime they produce
Many prokaryotes do not move at all
Obtaining Energy
 Autotrophs – produce their own food
Photoautotrophs – use light for the energy
source
 Example: cyanobacteria
 Chemoautotrophs – obtain energy from
inorganic molecules (such as ammonia)
 Heterotrophs – obtain energy by the food it
consumes
 Photoheterotrophs – obtain energy from light
and also from inorganic molecules

Releasing Energy
 Cellular respiration – requires oxygen
 Called
obligate aerobes
 Fermentation – does not require
oxygen
 Called obligate anaerobes
 Some bacteria can survive with or
without oxygen
 Called facultative anaerobes
Growth and Reproduction
 Replicates DNA and simply divides in half
(asexual reproduction)

Binary fission
 Some bacteria can transfer genetic
material from one cell to another

Conjugation
 When growth conditions become
unfavorable, some bacteria form
endospores to protect their genetic
material
Bacteria in Nature
 Decomposers – bacteria act as “recyclers
 Nitrogen fixation

Convert nitrogen from N2 into a form that plants
can use
 Bacteria and Disease – disease causing bacteria
are called pathogens

Bacteria cause disease in one of two ways
 Damage tissues by breaking them down for
food
 Release toxins (poisons) that harm the body
 Antibiotics can be used to kill bacteria
Common Diseases Caused by Bacteria
Section 19-2
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Section:
Disease
Pathogen
Prevention
Tooth decay
Streptococcus mutans
Regular dental hygiene
Lyme disease
Borrelia burgdorferi
Protection from tick bites
Tetanus
Clostridium tetani
Current tetanus vaccination
Tuberculosis
Mycobacterium tuberculosis
Vaccination
Salmonella food poisoning
Salmonella enteritidis
Proper food-handling practices
Pneumonia
Streptococcus pneumoniae
Maintaining good health
Cholera
Vibrio cholerae
Clean water supplies
Any Questions ?