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 sporozoan zooflagellate Sarcodine (amoeba)

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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