Prokaryotes and Protists
Chapter 16
Organizing Life
• Domains
– What are they?
• Linnaean hierarchy
– Arrangement of taxons
– http://animaldiversity.ummz.umich.edu/site/index.html
• Tree of Life
– Branched organization
– http://www.tolweb.org/tree/
• Cell Types
– Prokaryotes or eukaryotes
Comparing Cell Types
Prokaryotes
• 1-5 um in size
• 10X’s more biomass
• Wider range of environments
• Greater diversity
• Single, circular chromosome
• Can live without eukaryotes
Eukaryotes
• 10-100 um in size
• 10X’s larger in size
• Membrane bound nucleus
and organelles
• DNA arranged on multiple
chromosomes
• Can’t live without prokaryotes
Prokaryotic Shapes
 Cocci
 Sperical
 Chains or clusters
 E.g streptococci and staphylococci
(MRSA and beta-lactams)
 Bacilli
 Rod shaped
 Occur singularly, in pairs, or chains
 E.g. soil organisms
 Spirochetes
 Corkscrew shaped
 E.g. Borrelia burgdorferi (Lyme
disease)
Prokaryote Characteristics
 Cell wall
 Maintains shape, provides protection, and prevents lysis
 Salt and curing meats
 Gram stains identifed as gram (+) or gram (-)
 (+) simple walls with thicker peptidoglycan (sugar polymer)
 (-) more complex walls with less peptidoglycan
 More resistant to antibiotics
 Capsule
 Sticky polysaccharides or proteins to adhere to substrates
 Prevent immune system attacks
 Pili
 Hair-like appendages for adhesion
 Specialized for DNA transfer
Prokaryotic Characteristics
 Motility
 Many utilize a flagella
 Reproduction
 Review division by binary fission
 Occurs quickly (E. coli overnight from 1 to 16 million)
 Adaptation
 Form resistant structures like endospores during inhospitable times
 Bacillus anthracis (anthrax) and Clostridium botulinum (botulism)
 Internal Organization
 All DNA is actively used
 Lack junk DNA found in eukaryotes called __________?
 Small genetic rings that aid in resistance called plasmids
 Smaller ribosomal = efficiency of antibiotics
Prokaryotic Nourishment
• Unmatched diversity in nutrient attainment
• Nutrients provide energy and carbon
• Naming
– Photo- or chemo- = energy source
– Auto- or hetero- = carbon source
– -troph = to eat
Biofilms
• Surface coating colonies of prokaryotes
– Signal to recruit more cells and produce sticky proteins
– E.g. dental plaque, UTI’s, or sewer treatment
• Can be 1+ species
• Channels provide nutrients to entire colony
Prokaryotes
• Archaea
– Live where other organisms can’t survive,
‘extremophiles’
• Thermophiles
– Very hot water such as geysers and hot springs
• Halophiles
– Salt environments such as the Great Salt Lake and salt farms
• Methanogens
– Animal guts and swamps where they produce methane gas
• Bacteria
– Few species are pathogens, disease-causing organisms
– Most not harmful to humans
9 Bacterial Clades
• Proteobacteria (5 subgroups)
– Gram negative
•
•
•
•
Gram positive
Chlamydias
Spirochetes
Cyanobacteria
Proteobacteria
 Alpha (α)
 Rhizobium  root nodules, fix N2
 Foreign DNA carriers into crop plant genomes
 Gamma (γ)
 Photosynthetic examples
 Animal intestine inhabitants
 E.g Salmonella, Vibrio cholerae, and Escheria coli
 Delta (δ)
 Slime secreting myxobacteria
 Can form fruiting bodies for selves when food is scarce
 Bdellovibrio attacks other bacteria
Salmonella
Myxobacteria
Gram Positive
 Actinomycetes
 Branched chains of cells or are solitary
 Pathogenic or free-living
 Mycobacteria leprae and mycobacteria tuberculosis
 Live in soil and give it the ‘earthy’ smell
 Streptomyces
 Cultured by pharmaceutical companies as antibiotics
 Bacillus anthracis
 Form endospores, a cell within a cell that dehydrates and lies dormant
till more favorable conditions exist
Bacillus anthracis
 Staphylococcus and streptococcus
 Mycoplasmas
 Lack cell walls
 Tiniest of all known cells
Other Bacterial Clades
 Chlamydias
Chlamydia
 Obligate intracellular parasite
 Common cause of blindness (developing countries;
conjunctivitis) and most common STD (United
States)
 Spirochetes
 Spiral through environments by rotating internal
filaments
 E.g Treponema pallidum (syphilis) and Borrelia
burgdorferi (Lyme disease)
 Cyanobacteria
 Only Only prokaryote
 Food for freshwater and marine ecosystems
Bacterial Poisons
 Exotoxins are proteins secreted by bacteria
 Clostridium tetani produces muscle spasms (lockjaw)
 Staphylococcus aureus common on skin and in nasal passages
 Produces multiple types
 TSS, septicemia, and pneumonia
 Can be acquired from genetic transfer between species
 E. coli Acquires genes that produce harmful effects
 Endotoxins are components of gram (-) outer membranes
 Released when cell dies or digested by defensive cell
 All cause same general symptoms (fever, aches, and blood
pressure drops)
 Neisseria meningitidis (bacterial meningitis) and Salmonella (typhoid
fever and salmonellosis)
Bacteria, Human Populations, & Disease
• Improvements in sanitation
– Water treatment and sewer systems
• Antibiotic development
– Increase in bacterial resistance
• Education
– Importance of seeking treatment
– Prevention
• Biological weapons
• Bioremediation
Protists
• Single or multicellular eukaryotes
• Source of food and parasites
• Autotrophic (algae) or heterotrophic
(protozoan)
• Found in/near water (most) or in animal host
Protist Clades
• Regularly changing
hypotheses
• Divergence not truly
simultaneous
• Eukaryotic origin is
unknown
Diplomonads and Parabasalids
• Heterotrophs with altered mitochondria
• Diplomonads
–
–
–
–
Possibly most ancient Protist lineage
Mitochondria lack DNA & ETC
Anaerobic
E.g Giardia intestinalis ‘backpackers disease”
• Parabasalids
– Anaerobic energy generation
– E.g Trichomonas vaginalis (Trichomoniasis)
• Lives in the vagina
– pH shift to basic = growth
– Feed on WBC and bacteria
• Males rarely symptomatic b/c food availability
limits population size
• Treatment is available, but resistance is increasing
Euglenozoans
• Flagella have a crystalline rod structure
• Heterotrophs, photoautotrophs, &
pathogenic parasites
• E.g Trypanosoma
– Causes sleeping sickness
– Spread by African tsetse fly
– Avoid detection by changing protein structure
• E.g Euglena
– Common in pond water
– Reproduce by binary fission
– Simultaneously heterotrophic and autotrophic
Alveolates
• Contain alveoli, membranous sacs below
the PM
• Dinoflagellates
– Red tide blooms
– Toxins kill fish and can affect humans
• Ciliates
– Cilia to move and feed
– 2 types of nuclei, 1 for daily activities (single,
large) and 1 (many, small) for reproduction
• E.g Paramecium or Stentor
• Apicomplexans
– Animal parasites
• E.g Plasmodium (malaria)
Stramenopiles
• Have hairy and smooth flagella
• Water molds
– Decomposers in moist environments
– May be parasitic (Ireland potato famine)
• Diatoms
– Cell wall of silica
– Fresh and marine organism food source
– Diatomaceous earth
• Brown algae
– Autotrophic
– Kelp
Amoebozoans
• Use pseudopodia for movement and feeding
• Free-living amoebas
• Parasitic types
– E.g. amoebic dysentery
• Slime molds
– Organisms found in moist, decaying matter
– Spread under favorable conditions, form spore
producing structures under less favorable ones
• Plasmodial slime molds are brightly colored
– Single-celled plasmodium
– Cell cycle research
• Cellular slime molds solitary until food is scarce
– Cell differentiation research
Foraminiferans and Radiolarians
• Move and feed by thread like
psuedopodia
• Forams
– Marine and fresh water organisms
– Pseudopodia extend through tests of
calcium carbonate
• Radiolarians
– Marine
– Internal silica shell and organic outer test
Land Plant Relatives
• Red algae
– Carrageenan stabilizes yogurt,
chocolate milk, and pudding
– Nori in sushi
– Agar for medium plates
• Green algae
– Volvox, colonial hollow balls
composed of 100’s of
biflagellated cells