Introduction to Cells
Cells are the basic units of organisms
Cells can only be observed under
microscope
Basic types of cells:
Animal Cell
Plant Cell
Bacterial 1Cell
Cells May be Prokaryotic or
Eukaryotic
 Prokaryotes include bacteria & lack
a nucleus or membrane-bound
structures called organelles
Eukaryotes include most other cells &
have a nucleus and membrane-bound
organelles (plants, fungi, & animals)
copyright cmassengale
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Prokaryotes
• Most numerous
organisms on
Earth
• Include all
bacteria
• Earliest fossils
date 2.5 billion
years old
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Characteristics
of Bacteria
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Bacteria can have
Different shapes
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Bacillus - E. coli
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Staphylococcus
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Bacterial Structure
• Microscopic prokaryotes
• unicellular
• No nucleus or membranebound organelles
• Contain ribosomes – make
proteins
• Single, circular
chromosome in nucleoid
region - DNA
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Bacterial Cell
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Protection
• Cell Wall made of
Peptidoglycan
• May have a sticky
coating called the
Capsule for
attachment to host or
other bacteria
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Sticky Bacterial
Capsule
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Flagella
• Bacteria that are
motile have
appendages called
flagella
• A bacteria can have
one or many flagella
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Monotrichous
Lophotrichous
Amphitrichous
Peritrichous
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Pili
• Short protein
appendages
• Smaller than flagella
• Adhere bacteria to
surfaces
• Used in conjugation for
Exchange of genetic
information
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Pili in Conjugation
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Bacteria Replication
Binary
fission
Conjugation
Use pilus
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Bacteria
• Most grow best at
pH of 6.5 to 7.0
• Large portion of
bacteria are useful
• Only some cause
disease
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Useful Bacteria
• Some bacteria
can degrade
oil
• Used to clean
up oil spills
• Act as
decomposers –
nitrogen cycle
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Useful Bacteria
• Other uses
for bacteria
include
making
yogurt,
cheese, and
buttermilk.
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• E. Coli = Gram Negative
• Bacillus = Gram Positive
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BIOFILM
• The plaque that forms on teeth and causes
tooth decay
• Form when bacteria adhere to surfaces
and secrete a slimy, gluelike substance
• Forms communities of disease causing
bacteria
• Biofilms can form anywhere – clogged
drains, slippery rocks ect..
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How Antibiotics Work
• Interferes with cell wall – loses
protections
• Interferes with the bacteria’s ability to
make proteins
• Interferes with the ability to replicate
DNA
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Zone of inhibition
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INQUIRY LAB
• Test different types of mouthwash to
determine which type kills the most
bacteria.
• Use the principles of antibiotic testing
• Determine procedure – lab writeup
– Purpose, hypothesis, materials, procedure, data,
analysis, conclusion
• Decide which two types of mouthwash you
will test
• Measurements – zone of inhibition
• Come to a conclusion
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