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Three Domains of Life Proti sts
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Three Domains of Life Protists. Three Domains of Life.

Jan 04, 2016

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Archaebacteria & Eubacteria

Three Domains of Life

Protists1Archea have classified Kingdoms; Bacteria do not (yet)On the contrary, Eukaryota is composed of well-defined Kingdoms including Plants, Fungus and Animals; the exception is Protists which well discover are not monophyletic and include groups that are similar in design, but not in evolutionary processesThree Domains of Life

2Monophyletic; one c.a.Changes in ClassificationThe old school method of classification included 5 Kingdoms (what I learned in school)MoneraProtistaFungiPlantaeAnimaliaToday, advances in molecular technology expanded our understanding (and interpretation) of systematicsModern SystematicsThree Domain classification of life Numerous, virtually countless KingdomsBacteria and Archaea are now 2 distinct Domains (once included together in Kingdom Monera)Protista, Fungi, Plantae, and Animalia remain classified as distinct Kingdoms, although classification of the kingdom Protista has been met with complications

ProkaryotesIncludes the kingdoms Archaea & Bacteria Oldest, structurally-simplest, and most abundant forms of lifePhotosynthesis Bacterial and Eukaryotic DiversityImportant decomposers and symbionts5True bacteria; Existed on Earth for 1 billion years before the Eukaryotes appearedProkaryotesUnicellularTypically 1m or less (1000 m = 1mm; 1000mm = 1 meter)No membrane-bound nucleus; instead a single circular chromosome made of DNAAsexual reproduction by binary fissionPhotosynthetic bacteria utilize oxygen or chemical compounds, such as sulfur

6Although they can transfer genetic material via their plasmids (horizontal gene transfer), however not considered reproductionProkaryotic Cell StructureThree basic forms:Bacillus rod-shapedCoccus - sphercal or ovoid-shaped Spirillum spiral or helical

Prokaryotic Cell StructureProkaryotes have a tough cell wall and other external structuresCell wall consists of peptidoglycan; a rigid network of polysaccharide strands cross-linked by peptide side chains; unique to BacteriaMaintains the shape of the cell and protects it from swelling and rupturing

Prokaryotes can have 1 or more flagella (much less complex than in Eukaryotes)Some Prokaryotes possess pilli, which helps fasten cell to host membraneDomain ArchaeaOnce considered a subdivision of the Kingdom Monera, now its own domainLike all prokaryotes, Archaea are single-celled microorganisms that lack a nucleus and membrane-bound organellesBest known for the extremophiles Archaea which thrive in extremely harsh environments

Archea - ExtremophilesThermophiles thrive at 60-80C (>176F!)Acidophiles thrive at pH at or below pH 3Xerophiles grow in extremely dry conditionsHalophiles require extremely high concentrations of salt

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Dr. Anastasias lecture starts here13Molecular Classification

Bacteria and Archae differ fundamentallyCell WallBacterial cell walls are made of peptidoglycan, Archae are notGene expressionArchaea may have more than one RNA polymerase (Transcription: reads DNA to make RNA), and these enzymes more closely resemble the eukaryotic RNA polymerases than they do the single bacterial RNA polymerase

16Eukaryotic Origins

The nucleus and endoplasmic reticulum arose from infoldings of prokaryotic cell membraneEndosymbiotic theoryEukaryotic organelles evolved from a consortium of symbiotic prokaryotesmitochondria were aerobic heterotrophic prokaryotes chloroplasts were photosynthetic prokaryotes

Kingdom ProtistaEukaryoticMost are unicellular (there are some simple multicellular ones)Originally consisted of all unicellular eukaryoteswas paraphyleticThe 17 major protist phyla are grouped into six major monophyletic groups

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CiliatesApicomplexansArchaeaEubacteriaChromalveolataRhizariaArchaeplastidaExcavataAmoebozaOpisthokontaParabasalidDinoflagellatesAlveolataStramenopilaRhodophytaChlorophytesDiplomonadsEuglenozoaChoanoflagellatesAnimalsFungiAmoebozoaLand plantsCharophytesCercozoaForaminiferaRadiolaraBrown algaeDiatomsOomycetesFig. 29.5Paraphyletic includes common ancestor but not all descendentsCharacteristics Used to Classify ProtistsMode of locomotionmode of nutritionoverall body formpigments& others

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Second flagellumStigmaContractile vacuoleParamylon granuleNucleusChloroplastFlagellumPellicleMitochondrionBasal bodiesReservoirb.a.6 mFig. 29.8a: Andrew Syred/Photo Researchers, Inc.A ciliated protozoan

22Too diverse for one kingdom: a diatom, a unicellular "alga"

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PtychodiscusNoctilucaCeratiumGonyaulaxFig. 29.13Too diverse for one kingdom: Australian bull kelp (Durvillea potatorum)

Fig. 29.24

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+GametangiaGametophyte (n)Gametes+Gametangia+Gametophyte (n)SporesSporangiaSporophyte (2n)Germinatingzygoten2nZygoteMEIOSISFERTILIZATIONFig. 29.27 Dr. Diane S. Littler

Too diverse for one kingdom: Amoeba proteus, a unicellular "protozoan"

Too diverse for one kingdom: a slime mold (Physarum polychalum)

Kingdom FungiEukaryotes, mostly multicellular, heterotrophic, have cell walls (chitin)decomposers, food, some cause diseaseAcquire nutrients through absorptionMycologists believe there may be as many as 1.5 million fungal speciesFungi are classified into 5 major phyla based on mode of reproduction-Chytrids (aquatic, flagellated, ancestral)-Zygomycetes (bread molds)-Glomeromycetes (mycorrhizae)-Ascomycetes (bread yeast, truffles)-Basidiomycetes (mushrooms)

Kingdom FungiTable 32.1

33General Biology of the FungiMulticellular fungi consist of long, slender filaments called hyphae

-Some hyphae are continuous-Others are divided by septa34General Biology of the FungiA mass of connected hyphae is called a mycelium-It grows through and digests its substrate

Fungal mycelia

37Fungal Parasites and Pathogens

Largest Organism? Armillaria a pathogenic fungus 8 hectaresFungi Reproductionspores are produced either sexually or asexuallyhyphae and spore nuclei are haploid except for a brief diploid stage that occurs during sexual reproductionFigure 31.3 Generalized life cycle of fungi (Layer 1)

Figure 31.3 Generalized life cycle of fungi (Layer 2)

Figure 31.3 Generalized life cycle of fungi (Layer 3)

Figure 31.6 The common mold Rhizopus decomposing strawberries

43Zygomycetes

Lichens

Mutualism between fungi and algae or cyanobacteriaSensitive to pollution due to absorption capabilituesFig. 32.15Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

a.b.c.Fruticose LichenCrustose LichenFoliose Lichena: Ken Wagner/Phototake; b: Robert & Jean Pollock/Visuals Unlimited; c: Robert Lee/Photo Researchers, Inc.Fig. 32.16Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

AlgalcellsFungalhyphae40 m Ed Reschke Mycorrhizae

Mutualism between fungi and the roots of 90% of all vascular plantsIncreases absorption of phosphorous, zinc & other nutrientsFig. 32.17Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

a.b.Root50 m5 mArbuscular MycorrhizaeEctomycorrhizaea: Eye of Science/Photo Researchers, Inc.; b: Dr. Gerald Van Dyke/Visuals Unlimited

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