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Introduction to CellsCells are the basic units of
organismsCells can only be observed under
microscopeBasic types of cells:
Animal Cell Plant CellBacterial Cell
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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)
Cells May be Prokaryotic or Eukaryotic
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
membrane-bound 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
ConjugationUse 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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