Transcript Bacteria , Viruses, Protists , and Prions

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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