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BACTERIA
Structure, Function, Reproduction, and
Growth
CLASSIFYING PROKARYOTES
There are two groups or kingdoms:
Eubacteria Live almost everywhere
Archaebacteria Live in harsh environments May be the ancestors of
eukaryotes
COMPARE THE KINGDOMS
are classified into the kingdoms of
live in harsh environments such as
include a variety of lifestyles such as
Eubacteria Archaebacteria
Infecting large organisms Thick mudLiving in soil
Animal digestive
tractsSalty lakes Hot springs
Bacteria
WHAT ARE BACTERIA?
Single-celled organisms Prokaryotes
No distinct nucleus No membrane-bound organelles
Size = 1-5 micrometers Very small, very primitive cells
About 10 times smaller than eukaryotic cells
HOWEVER, they are much larger than viruses
IDENTIFYING PROKARYOTES
Prokaryotes are identified by: Their shape The ways they move The ways they obtain energy
BACTERIA SHAPES
Bacteria come in three basic shapes
Coccus Round, spheres
Bacillus Rods
Spirillum Spiral or spring-like
MOVEMENT
Some are propelled by a flagellum
Some glide slowly along a layer of slime-like material they secrete
Some do not move at all
OBTAINING ENERGY Autotrophs
PhotoautotrophsCarry out photosynthesis (cyanobacteria)
ChemoautotrophsObtain energy from inorganic molecules (ie.
Ammonia, hydrogen sulfide, nitrites, sulfur, or iron
Heterotrophs Take in organic molecules and then break
them down Photoheterotrophs
Combination between autotrophs and heterotrophs; they photosynthesize and need organic compounds for nutrition
BACTERIA GROW IN GROUPS
Diplo Pairs
Strepto Chains
Staphlo Clusters
diplococcus diplobacillus
streptobacillus
streptococcus
staphlobacillus
staphlococcus
REPRODUCTIONBinary fission
Asexual Cell grows nearly double in size, replicates its DNA, and divides in half
Produces 2 identical “daughter” cells
View binary fission
WHAT BACTERIA NEED FOR GROWTH
Moisture Food Warm temperature Most need oxygen (aerobic bacteria),
however, some die in the presence of oxygen (anaerobic bacteria)
Where are these growth requirements met? Incubators Inside bodies of birds and mammals
WHAT STOPS BACTERIA GROWTH?
Cold temperature Dryness (freeze-dried foods) No food No oxygen (for aerobes)
BACTERIA
Beneficial and Harmful Aspects
BENEFICIAL ASPECTS Help digest food in
intestine Help in food
processing Break down waste in
sewage Ferment sugars to
make alcohol Can be used to make
medicine Decompose dead
organisms to return nutrients to soil or water
Some help fertilize soil by forming nitrates and nitrites Nitrogen-fixing
bacteria living on plant roots Convert
nitrogen into ammonia (form that plants can use)
Can be used to clean up oil spills Petroleum
eating bacteria
HARMFUL ASPECTS Spoils food
At home In stores In transit In restaurants In the field
Contaminate water Cholera & typhoid
Contaminate food Salmonella &
botulismFood needs to be
pasteurized (heated up to a really high temperature)
Damage leather Soil bacteria
Cause disease Only 1 percent of
bacteria cause disease
COMMON DISEASES CAUSED BY
BACTERIA
Tooth decayLyme diseaseTetanusTuberculosisSalmonella food poisoningPneumoniaCholera
Streptococcus mutansBorrelia burgdorferiClostridium tetaniMycobacterium tuberculosisSalmonella enteritidisStreptococcus pneumoniaeVibrio cholerae
Regular dental hygieneProtection from tick bitesCurrent tetanus vaccinationVaccinationProper food-handling practicesMaintaining good healthClean water supplies
Disease Pathogen Prevention