Unit 6--Microbiology

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Unit 6--Microbiology

• Chapter 20
• Protists

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Endosymbiotic theory

• Heterotrophic bacteria have plasmids (DNA loop)
  simple ribosomes in their cytoplasm
• Mitochondria have circular DNA bacteria-like
  ribosomes
• SoEukaryotic cells may have engulfed prokaryotic
  cells by mutualism created the first
  mitochondria.

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• Autotrophic bacteria are Cyanobacteria with
  chlorophyll
• So, Eukaryotic cells may have engulfed
  prokaryotic cyanobacteria by mutualism created
  the first chloroplast.

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Characteristics

• Mostly unicellular
• Eukaryotic cells
• Most diverse kingdom
• Photosynthesis, like plants (algae)
• Ingest food, like animals (protozoans)
• Absorb food, like fungus (slime mold)

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Classifying protists
DNA evidence shows that some archaebacteria
may have been ancestors of protists.
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Phylumexampledistinguishing characteristics

• Zoomastigina Trypanosome
• Causes Sleeping sickness
• All are flagellated
• Other examples include those living symbiotically
  within termite intestine

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Phylumexampledistinguishing characteristics

• Rhizopodaameba
• Moves by pseudopods cytoplasmic extensions
• Feed by phagocytosis surrounding engulfing

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Phylumexampledistinguishing characteristics

• Foraminifera Forams
• Ameba-like body within a shell-like test
• Often build-up accumulates after many years

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Electron microphotograph of Radiolarian, a marine
Protist
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Phylumexampledistinguishing characteristics

• Ciliophora paramecium
• All are ciliated
• Macro micronuclei
• Oral groove gullet bring food into vacuole
• Contractile vacuole pumps out water

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See page 501
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Phylumexampledistinguishing characteristics

• Sporozoa Plasmodium
• Causes Malaria
• Carried by female Anopheles mosquito
• During bite insect saliva inserted or infected
  blood ingested by insect

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See page 503
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Plasmodium attacking red blood cells and
rupturing RBC
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Phylumexampledistinguishing characteristics

• Euglenophyta Euglena
• Animal-like flagella, eyespot, and reservoir (to
  ingest)
• Plant-like chloroplasts for photosynthesis

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Euglena structures
Pellicle EM image
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See page 507
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Phylumexampledistinguishing characteristics

• Bacillariophyta Diatoms
• Unicellular marine algae main producer in the
  sea
• Glass-like cell walls of silica
• Unique shapes

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Phylumexampledistinguishing characteristics

• Dinoflagellata dinoflagellates
• Unicellular algae 2nd only to diatoms as main
  producer
• Often has flagella, plates, spikes, and other
  projections
• Causes red tide

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Bioluminescence
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Phylumexampledistinguishing characteristics

• Rhodophytared algae
• Small, multicellular algae
• May be an epiphyte on larger algae
• Used to make agar

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Phylumexampledistinguishing characteristics

• Phaeophyta brown algae
• Largest, multicellular algae
• Includes Kelp, which may grow 100 ft
• Plant-like body with holdfasts, stalks and
  blades, air bladders for support

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Sargasso Sea
Sargassum
Many square kilometers of the open Atlantic Ocean
between the islands of the Azores and the
Bahamas are covered by huge, floating algae
called Sargassum. Known as the Sargasso Sea,
this area of warm water is named for the brown
algae that dominate its surface.
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Uses of red and brown algae
Agar
Seaweed
Carrageenan
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Phylumexampledistinguishing characteristics

• Chlorophyta green algae
• Ancestors of plants
• In all environments, even on land
• Unicellular to multicellular (sea lettuce)
• Ex Volvox and Spirogyra

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Conjugation in Paramecium
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Phylumexampledistinguishing characteristics

• Myxomycota plasmodial slime mold
• A mass of cytoplasm containing many nuclei
• Uses spores to survive harsh conditions

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Acellular slime mold plasmodium
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Cellular slime mold