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Page 1: Three Domains of Life Protists. Three Domains of Life.

Three Domains of Life

Protists

Page 2: Three Domains of Life Protists. Three Domains of Life.

Three Domains of Life

Page 3: Three Domains of Life Protists. Three Domains of Life.

Changes in Classification• The ‘old school’ method of classification included 5

Kingdoms (what I learned in school)– Monera– Protista– Fungi– Plantae– Animalia

• Today, advances in molecular technology expanded our understanding (and interpretation) of systematics

Page 4: Three Domains of Life Protists. Three Domains of Life.

Modern Systematics• Three Domain classification of life • Numerous, virtually countless Kingdoms• Bacteria 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

Page 5: Three Domains of Life Protists. Three Domains of Life.

Prokaryotes

• Includes the kingdoms Archaea & Bacteria • Oldest, structurally-simplest, and most

abundant forms of life• Photosynthesis Bacterial and Eukaryotic

Diversity• Important decomposers and symbionts

Page 6: Three Domains of Life Protists. Three Domains of Life.

Prokaryotes

• Unicellular• Typically 1μm or less (1000 μm = 1mm;

1000mm = 1 meter)• No membrane-bound nucleus; instead a

single circular chromosome made of DNA• Asexual reproduction by binary fission• Photosynthetic bacteria utilize oxygen or

chemical compounds, such as sulfur

Page 7: Three Domains of Life Protists. Three Domains of Life.

Prokaryotic Cell Structure• Three basic forms:

– Bacillus – rod-shaped– Coccus - sphercal or ovoid-shaped – Spirillum – spiral or helical

Page 8: Three Domains of Life Protists. Three Domains of Life.

Prokaryotic Cell Structure• Prokaryotes have a tough cell wall and other

external structures• Cell wall consists of peptidoglycan; a rigid

network of polysaccharide strands cross-linked by peptide side chains; unique to Bacteria

• Maintains the shape of the cell and protects it from swelling and rupturing

Page 9: Three Domains of Life Protists. Three Domains of Life.

• Prokaryotes can have 1 or more flagella (much less complex than in Eukaryotes)

• Some Prokaryotes possess pilli, which helps fasten cell to host membrane

Page 10: Three Domains of Life Protists. Three Domains of Life.

Domain Archaea• Once considered a subdivision of the Kingdom

Monera, now its own domain• Like all prokaryotes, Archaea are single-celled

microorganisms that lack a nucleus and membrane-bound organelles

• Best known for the “extremophiles” – Archaea which thrive in extremely harsh environments

Page 11: Three Domains of Life Protists. Three Domains of Life.

Archea - Extremophiles• Thermophiles – thrive at

60-80°C (>176°F!)• Acidophiles – thrive at pH

at or below pH 3• Xerophiles – grow in

extremely dry conditions• Halophiles – require

extremely high concentrations of salt

http://www.dpchallenge.com/image.php?IMAGE_ID=448561

Page 12: Three Domains of Life Protists. Three Domains of Life.

Dr. Anastasia’s lecture starts here

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13

Molecular Classification

Page 14: Three Domains of Life Protists. Three Domains of Life.

Bacteria and Archae differ fundamentally

• Cell Wall– Bacterial cell walls are made of peptidoglycan, Archae are not

• Gene expression– Archaea 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

Page 15: Three Domains of Life Protists. Three Domains of Life.
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16

Eukaryotic OriginsThe nucleus and

endoplasmic reticulum arose from infoldings of prokaryotic cell membrane

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Endosymbiotic theory• Eukaryotic organelles

evolved from a consortium of symbiotic prokaryotes– mitochondria were

aerobic heterotrophic prokaryotes

– chloroplasts were photosynthetic prokaryotes

Page 18: Three Domains of Life Protists. Three Domains of Life.

Kingdom Protista• Eukaryotic• Most are unicellular (there are some simple

multicellular ones)• Originally consisted of all unicellular eukaryotes• was paraphyletic• The 17 major protist phyla are grouped into six

major monophyletic groups

Page 19: Three Domains of Life Protists. Three Domains of Life.

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Cil

iate

s

Ap

ico

mp

lex

ans

ArchaeaEubacteria Chromalveolata Rhizaria Archaeplastida Excavata Amoeboza Opisthokonta

Par

aba

sal

id

Din

ofl

ag

ella

tes

Alveolata Stramenopila Rhodophyta Chlorophytes Diplomonads Euglenozoa Choanoflagellates

An

ima

ls

Fu

ng

i

Am

oeb

ozo

a

La

nd

pla

nts

Ch

aro

ph

yte

s

Ce

rco

zoa

Fo

ram

inif

era

Ra

dio

lara

Bro

wn

alg

ae

Dia

tom

s

Oo

myc

ete

s

Fig. 29.5

Paraphyletic – includes common

ancestor but not all descendents

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Characteristics Used to Classify Protists

• Mode of locomotion• mode of nutrition• overall body form• pigments• & others…

Page 21: Three Domains of Life Protists. Three Domains of Life.

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Second flagellumStigma

Contractile vacuole

Paramylon granule

Nucleus

ChloroplastFlagellum

Pellicle

MitochondrionBasal bodies

Reservoir

b.

a. 6 µm

Fig. 29.8

a: © Andrew Syred/Photo Researchers, Inc.

Page 22: Three Domains of Life Protists. Three Domains of Life.

A ciliated protozoan

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

Page 24: Three Domains of Life Protists. Three Domains of Life.

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Ptychodiscus

Noctiluca

Ceratium

Gonyaulax

Fig. 29.13

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

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Fig. 29.24

Page 27: Three Domains of Life Protists. Three Domains of Life.

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

+

Gametangia

Gametophyte (n)

Gametes

+Gametangia

+Gametophyte (n)

Spores

Sporangia

Sporophyte (2n)

Germinatingzygote

n

2n

Zygote

MEI

OSI

S

FERTILIZATION

Fig. 29.27

© Dr. Diane S. Littler

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

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

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Kingdom Fungi

• Eukaryotes, mostly multicellular, heterotrophic, have cell walls (chitin)

• decomposers, food, some cause disease• Acquire nutrients through absorption

Page 31: Three Domains of Life Protists. Three Domains of Life.

Mycologists believe there may be as many as 1.5 million fungal species

Fungi 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 Fungi

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Table 32.1

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33

General Biology of the FungiMulticellular fungi consist of long, slender

filaments called hyphae

-Some hyphae are continuous

-Others are divided by septa

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34

General Biology of the FungiA mass of connected hyphae is called a mycelium

-It grows through and digests its substrate

Page 35: Three Domains of Life Protists. Three Domains of Life.

Fungal mycelia

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37

Fungal Parasites and Pathogens

Largest Organism? Armillaria –a pathogenic fungus – 8 hectares

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Fungi Reproduction• spores are produced either sexually or asexually• hyphae and spore nuclei are haploid

– except for a brief diploid stage that occurs during sexual reproduction

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Figure 31.3 Generalized life cycle of fungi (Layer 1)

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Figure 31.3 Generalized life cycle of fungi (Layer 2)

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Figure 31.3 Generalized life cycle of fungi (Layer 3)

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Figure 31.6 The common mold Rhizopus decomposing strawberries

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43

Zygomycetes

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Lichens

• Mutualism between fungi and algae or cyanobacteria

• Sensitive to pollution due to absorption capabilitues

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Fig. 32.15Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

a. b. c.

Fruticose Lichen Crustose LichenFoliose Lichen

a: © Ken Wagner/Phototake; b: © Robert & Jean Pollock/Visuals Unlimited; c: © Robert Lee/Photo Researchers, Inc.

Page 46: Three Domains of Life Protists. Three Domains of Life.

Fig. 32.16Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Algalcells

Fungalhyphae

40 μm © Ed Reschke

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Mycorrhizae

• Mutualism between fungi and the roots of 90% of all vascular plants

• Increases absorption of phosphorous, zinc & other nutrients

Page 48: Three Domains of Life Protists. Three Domains of Life.

Fig. 32.17Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

a. b.

Root

50 µm5 µm

Arbuscular Mycorrhizae Ectomycorrhizae

a: © Eye of Science/Photo Researchers, Inc.; b: © Dr. Gerald Van Dyke/Visuals Unlimited