bacteria, viruses, prions, and protists. bacteria unicellular or multicellular? prokaryotic or...
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Bacteria, Viruses, Prions, and Protists
Bacteria
• Unicellular or Multicellular?
• Prokaryotic or Eukaryotic?
• Cells Walls?
Bacteria
• Unicellular
• Prokaryotes
• Cells walls containing peptidoglycan
Bacteria
• Extremely Abundant– Cover nearly every square centimeter of Earth
What are the differences between eubacteria and
archaebacteria?
Eubacteria versus Archaebacteria
• Cell walls of Eubacteria have peptidoglycans while those of Archaebacteria do not.
• DNA sequences of archaebacteria is more similar to that of eukaryotes than to the DNA of eubacteria
• Archaebacteria often live in very extreme environments (hot springs, digestive tracts, Great Salt Lake, etc.)
Bacterial Shapes
• Bacilli: rod shaped
• Cocci: spherical
• Spirilla: spiral, corkscrew
Cell Walls
• Gram positive: stain violet due to thick peptidoglycan walls
• Gram negative: stain pink/red, have much thinner walls inside lipid layer
Metabolism
Heterotrophs:
• Chemoheterotrophs: must take in organic molecules and a supply of carbon
• Photoheterotrophs: are photosynthetic but also need to take in organic molecules for carbon source
Metabolism
• Photoautotrophs: use light energy to make carbon compounds
• Chemoautotrophs: use energy from chemical reactions to make carbon compounds
• Where might each type of bacteria be found?
Binary Fission
• When a bacteria grows so that it has doubled in size, it replicates its DNA and divides in half
• Is this sexual or asexual?
• Identical or different daughter cells?
Conjugation
• Some bacteria are able to exchange genetic information
• A hollow bridge forms between two bacteria and genes move from one cell to the other
• Increases genetic diversity of a population
Conjugation
Spore Formation
• Spores are formed when the bacteria produces a thick internal wall that encloses the DNA and part of the cytoplasm
• Why do you think this would be beneficial for bacteria?
Spore Formation
• Occurs when conditions are unfavorable for growth
• Can remain dormant for years until conditions improve
Spore Formation
What are some benefits of bacteria?
Benefits of Bacteria• Some are producers that undergo
photosynthesis
• Some are decomposers that break down dead matter to recycle the nutrients
• Some convert nitrogen gas to a form that can be used by plants (nitrogen fixation)
What are some dangers of bacteria?
Dangers of Bacteria
• Break down cells and tissues for food Example: Tuberculosis (destroys lung
tissue)
• Release toxins (poisons) that travel through the body
Example: Streptococcus releases toxins into the blood stream causes strep throat and scarlet fever
Vaccines
• A vaccine is a preparation of weakened or killed pathogens that are injected into the body
• This stimulates the body to produce immunity to the disease
Vaccines
• Why do you think we don’t vaccinate everyone for all disease we have created vaccines for?
Antibiotics
• Antibiotics block the growth and reproduction of bacteria
• Used to treat bacterial infections
Solve the Problem
• What would you do to find out what causes the tobacco leaves to be diseased?
Viruses
• A virus is a core of DNA or RNA surrounded by a protein coat (capsid)
Viruses• They can only reproduce by infecting living
cells
• They enter a cell and use its cell machinery to produce more viruses
Retroviruses
• Contain RNA as genetic information instead of DNA
Would you consider viruses living?
Are Viruses Living?
• Cannot reproduce alone, must have a host cell
• Do not undergo growth or development
• Do not obtain or use energy
• Evolve
Prions
• Diseases such as Scrapie (in sheep) and Mad Cow Disease are not caused by bacteria or viruses. What could cause them?
Prions
• Contain only protein
• Cause disease by forming protein clumps which then induce normal proteins to become Prions
• The build up eventually damages nerve tissue
Protists
• Domain?
• Kingdom?
• Prokaryotic or Eukaryotic?
Protists
• Domain: Eukarya
• Kingdom: Protists
• Eukaryotic
Protists
• Protists are defined by what they are not.
Protists are eukaryotes that are not animals, plants, or fungi.
They were the first eukaryotic organisms on earth.
Types of Protists
• Animal-Like Protists: heterotrophs
• Plant-Like Protists: produce food through photosynthesis
• Fungus-Like Protists: obtain food by external digestion
Animal-Like Protists
• Heterotrophs
cilliate
Sarcodine (amoeba)
sporozoan
zooflagellate
Animal-Like Protists
• Malaria
• African Sleeping Sickness
Plant-Like Protists
• Carry out photosynthesis
Fungus-Like Protists
• Grow in damp, nutrient rich environments
• Absorb food through cell membranes
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