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 ShapesCocci

SpericalChains or clustersE.g streptococci and staphylococci

(MRSA and beta-lactams)Bacilli

Rod shaped Occur singularly, in pairs, or chainsE.g. soil organisms

SpirochetesCorkscrew shapedE.g. Borrelia burgdorferi (Lyme

disease)

Prokaryote CharacteristicsCell wall

Maintains shape, provides protection, and prevents lysisSalt 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 substratesPrevent immune system attacks

PiliHair-like appendages for adhesionSpecialized for DNA transfer

Prokaryotic Characteristics

MotilityMany utilize a flagella

ReproductionReview division by binary fissionOccurs quickly (E. coli overnight from 1 to 16 million)

AdaptationForm 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 plasmidsSmaller 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

ProteobacteriaAlpha (α)

Rhizobium root nodules, fix N2Foreign DNA carriers into crop plant genomes

Gamma (γ)Photosynthetic examplesAnimal intestine inhabitants

E.g Salmonella, Vibrio cholerae, and Escheria coliDelta (δ)

Slime secreting myxobacteriaCan form fruiting bodies for selves when food is scarce

Bdellovibrio attacks other bacteria

Salmonella

Myxobacteria

Gram PositiveActinomycetes

Branched chains of cells or are solitaryPathogenic or free-living

Mycobacteria leprae and mycobacteria tuberculosis Live in soil and give it the ‘earthy’ smell

StreptomycesCultured by pharmaceutical companies as antibiotics

Bacillus anthracisForm endospores, a cell within a cell that dehydrates and lies dormant

till more favorable conditions existStaphylococcus and streptococcusMycoplasmas

Lack cell wallsTiniest of all known cells

Bacillus anthracis

Other Bacterial CladesChlamydias

Obligate intracellular parasiteCommon cause of blindness (developing countries;

conjunctivitis) and most common STD (United States)

SpirochetesSpiral through environments by rotating internal

filamentsE.g Treponema pallidum (syphilis) and Borrelia

burgdorferi (Lyme disease)Cyanobacteria

Only Only prokaryoteFood for freshwater and marine ecosystems

Chlamydia

Bacterial Poisons

Exotoxins are proteins secreted by bacteriaClostridium tetani produces muscle spasms (lockjaw)Staphylococcus aureus common on skin and in nasal passages

Produces multiple typesTSS, septicemia, and pneumonia

Can be acquired from genetic transfer between speciesE. coli Acquires genes that produce harmful effects

Endotoxins are components of gram (-) outer membranesReleased when cell dies or digested by defensive cellAll 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