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Chapter 12. Characterizing and Classifying Eukaryotes . General Characteristics of Eukaryotic Organisms. Five major groups Protozoa Fungi Algae Water molds Slime molds Include both human pathogens and organisms vital for human life. © 2012 Pearson Education Inc.

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Chapter 12

Characterizing and Classifying Eukaryotes


General characteristics of eukaryotic organisms l.jpg
General Characteristics of Eukaryotic Organisms

Five major groups

Protozoa

Fungi

Algae

Water molds

Slime molds

Include both human pathogens and organisms vital for human life

© 2012 Pearson Education Inc.


General characteristics of eukaryotic organisms3 l.jpg
General Characteristics of Eukaryotic Organisms

Reproduction in Eukaryotes

More complicated than reproduction in prokaryotes

Eukaryotic DNA packaged as chromosomes in the nucleus

Have variety of methods of asexual reproduction

Many reproduce sexually by forming gametes and zygotes

Algae, fungi, and some protozoa reproduce both sexually and asexually

© 2012 Pearson Education Inc.


General characteristics of eukaryotic organisms4 l.jpg
General Characteristics of Eukaryotic Organisms

Reproduction in Eukaryotes

Nuclear division

Nucleus has one or two complete copies of genome

Single copy (haploid)

Most fungi, many algae, some protozoa

Two copies (diploid)

Remaining fungi, algae, and protozoa

Two types

Mitosis

Meiosis

© 2012 Pearson Education Inc.


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General Characteristics of Eukaryotic Organisms

Reproduction in Eukaryotes

Nuclear division

Mitosis

Cell partitions replicated DNA equally between two nuclei

Maintains ploidy of parent nucleus

Four phases

Prophase

Metaphase

Anaphase

Telophase

© 2012 Pearson Education Inc.


Figure 12 1a mitosis l.jpg

Mitosis

Diploid nucleus(2n)

Figure 12.1a Mitosis

DNA replication

Prophase I

Chromosome(twochromatids)

Centromere

Metaphase

Spindle

Anaphase

Telophase

Nuclearenvelope

Two diploid nuclei (2n)


General characteristics of eukaryotic organisms7 l.jpg
General Characteristics of Eukaryotic Organisms

Reproduction in Eukaryotes

Nuclear division

Meiosis

Nuclear division that partitions chromatids into four nuclei

Diploid nuclei produce haploid daughter nuclei

Two stages – meiosis I and meiosis II

Each stage has four phases

Prophase

Metaphase

Anaphase

Telophase

© 2012 Pearson Education Inc.


Figure 12 1b1 meiosis i l.jpg

Meiosis

Diploid nucleus(2n)

Figure 12.1b1 Meiosis I

DNA replication

Prophase I

Tetrad(two homologouschromosomes,four chromatids)

Late prophase I

Crossing over

MEIOSIS I

Metaphase I

Anaphase I

Chromosome(two chromatids)

Telophase I


Figure 12 1b2 meiosis ii l.jpg

Prophase II

Figure 12.1b2 Meiosis II

Metaphase II

Anaphase II

MEIOSIS II

Telophase II

Nuclear envelope

Four haploid nuclei (1n)


General characteristics of eukaryotic organisms10 l.jpg
General Characteristics of Eukaryotic Organisms

Reproduction in Eukaryotes

Cytokinesis (cytoplasmic division)

Typically occurs simultaneously with telophase of mitosis

In some algae and fungi, postponed or does not occur at all

Results in multinucleated cells called coenocytes

© 2012 Pearson Education Inc.


Figure 12 2 different types of cytoplasmic division overview l.jpg

Figure 12.2 Different types of cytoplasmic division-overview


Figure 12 3 schizogony l.jpg

Figure 12.3 Schizogony

Merozoites

Nucleus

Schizont

Multiple mitoses

Cytokinesis


Figure 12 4 the changing classification of eukaryotes over the centuries overview l.jpg

Figure 12.4 The changing classification of eukaryotes over the centuries-overview


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Protozoa

Diverse group defined by three characteristics

Eukaryotic

Unicellular

Lack a cell wall

Motile by means of cilia, flagella, and/or pseudopodia

Except subgroup, apicomplexans

© 2012 Pearson Education Inc.


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Protozoa

Distribution of Protozoa

Require moist environments

Most live in ponds, streams, lakes, and oceans

Critical members of plankton

Others live in moist soil, beach sand, and decaying organic matter

Very few are pathogens

© 2012 Pearson Education Inc.


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Protozoa

Morphology of Protozoa

Great morphologic diversity

Some have two nuclei

Macronucleus

Contains many copies of the genome

Micronucleus

Variety in number and kinds of mitochondria

Some have contractile vacuoles

All produce trophozoites; some produce cysts

© 2012 Pearson Education Inc.


Figure 12 5 contractile vacuole overview l.jpg

Open vacuole

Closed vacuole

Figure 12.5 Contractile vacuole-overview


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Protozoa

Nutrition of Protozoa

Most are chemoheterotrophic

Obtain nutrients by phagocytizing bacteria, decaying organic matter, other protozoa, or the tissues of host

Few absorb nutrients from surrounding water

Dinoflagellates and euglenoids are photoautrophic

© 2012 Pearson Education Inc.


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Protozoa

Reproduction in Protozoa

Most reproduce asexually only

Binary fission or schizogony

Few also have sexual reproduction

Some become gametocytes that fuse with one another to form diploid zygotes

Some utilize a process called conjugation

© 2012 Pearson Education Inc.


Figure 12 6 sexual reproduction via conjugation in ciliates l.jpg

Diploid micronuclei

Haploid micronuclei

Meiosis of micronucleiproduces four haploidmicronuclei in each.

Three micronuclei in eachdisintegrate; the remainingtwo replicate by mitosis.

Compatiblemates

Figure 12.6 Sexual reproduction via conjugation in ciliates

Mates couple.

Mates each swap one micronucleus.

Haploidmicronucleus(1n)

Diploidmicronucleus(2n)

Micronucleus(50n)

Partnersseparate.

Original macronucleusdisintegrates. Fourmicronuclei becomemacronuclei by replicatingchromosomes numeroustimes; four micronucleiremain micronuclei.

Three cytokinesespartition a macronucleusand a micronucleus intoeach of four daughter cells.

Three mitoseswithoutcytokinesisproduce eightmicronuclei.

The two differentmicronuclei fuseto form diploidmicronucleus.


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Protozoa

Classification of Protozoa

Based on 18S rRNA and features visible by electron microscopy

One scheme classifies into six taxa

© 2012 Pearson Education Inc.


Figure 12 7 trichonympha acuta a parabasalid with prodigious flagella l.jpg

Figure 12.7 Trichonympha acuta, a parabasalid with prodigious flagella


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Protozoa

Classification of Protozoa

Diplomonadida

Lack mitochondria, Golgi bodies, peroxisomes

Prominent example is Giardia

© 2012 Pearson Education Inc.


Figure 12 8a euglena l.jpg

Flagellum

Figure 12.8a Euglena

“Eyespot”

Short second flagellum

Contractile vacuole

Paramylon granule

Nucleus

Chloroplasts

Pellicle


Figure 12 8b trypanosoma l.jpg

Figure 12.8b Trypanosoma

Kinetoplast

Nucleus


Figure 12 9 alveoli membrane bound structures found in some protozoa l.jpg

Alveoli

Figure 12.9 Alveoli membrane-bound structures found in some protozoa


Figure 12 10 a predatory ciliate didinium devouring another ciliate paramecium l.jpg

Figure 12.10 A predatory ciliate, Didinium, devouring another ciliate, Paramecium


Figure 12 11 peridinium a motile armored dinoflagellate l.jpg

Cellulose plate

Figure 12.11 Peridinium, a motile armored dinoflagellate

Transverseflagellum

Longitudinalflagellum


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Figure 12.12 Rhizaria called foraminifera have multichambered, snail-like shells of calcium carbonate


Figure 12 13 rhizaria called radiolarians have ornate shells of silica l.jpg

Figure 12.13 Rhizaria called radiolarians have ornate shells of silica


Figure 12 14a a plasmodial acellular slime mold l.jpg

Haploid

Figure 12.14a A plasmodial (acellular) slime mold

Compatiblemyxamoebae fuse.

Myxamoebaegerminatefrom spores.

Spore (n)

Zygote (2n)

Haploidsporesarereleased.

Plasmodium

Sporangium

Coenocyticplasmodium(2n)

Sporania grow fromplasmodial masses.

Diploid


Figure 12 14b a cellular slime mold l.jpg

Figure 12.14b A cellular slime mold

Spores arereleased.

Haploid

Nucleus

Spore

Myxamoebagerminatesfrom spore.

Sporangium

Fruiting body withsporangium

Slug

Slug forms stalk.

Myxamoebae congregate to formpseudoplasmodium (slug), butthey retain their individuality.


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Fungi

Chemoheterotrophic

Have cell walls typically composed of chitin

Do not perform photosynthesis

Lack chlorophyll

Related to animals

© 2012 Pearson Education Inc.


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Fungi

The Significance of Fungi

Decompose dead organisms and recycle their nutrients

Help plants absorb water and minerals

Used for food and in manufacture of foods and beverages

Produce antibiotics

Serve as important research tools

30% cause diseases of plants, animals, and humans

Can spoil fruit, pickles, jams, and jellies

© 2012 Pearson Education Inc.


Figure 12 15 fungal morphology overview l.jpg

Figure 12.15 Fungal morphology-overview


Figure 12 16 a fungal mycelium growing on a leaf l.jpg

Figure 12.16 A fungal mycelium growing on a leaf


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Fungi

Nutrition of Fungi

Acquire nutrients by absorption

Most are saprobes

Some trap and kill microscopic soil-dwelling nematodes

Haustoria allow some to derive nutrients from living plants and animals

May use ionizing radiation as energy source

Most fungi are aerobic

Many yeasts are facultative anaerobes

© 2012 Pearson Education Inc.


Figure 12 17 predation of a nematode by the fungus arthrobotrys l.jpg

Nematode

Figure 12.17 Predation of a nematode by the fungus Arthrobotrys

Hyphal loop


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Fungi

Reproduction in Fungi

All have some means of asexual reproduction involving mitosis and cytokinesis

Most also reproduce sexually

© 2012 Pearson Education Inc.


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Fungi

Reproduction in Fungi

Budding and asexual spore formation

Yeasts bud in manner similar to prokaryotic budding

Pseudohypha

Series of buds that remain attached to one another and to parent cell

Filamentous fungi produce lightweight spores that disperse over large distances

© 2012 Pearson Education Inc.


Figure 12 18 representative asexual spores of molds overview l.jpg

Figure 12.18 Representative asexual spores of molds-overview


Figure 12 19 the process of sexual reproduction in fungi l.jpg

Tips fuse

Figure 12.19 The process of sexual reproduction in fungi

Dikaryoticstage(nn)

Dikaryon

2 nucleiper cell

Diploidstage(2n)

Meiosis

Nucleifuse

Haploidstage(n)


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Fungi

Classification of Fungi

Division Zygomycota

Division Ascomycota

Division Basidiomycota

Deuteromycetes

© 2012 Pearson Education Inc.


Figure 12 20 life cycle of the zygomycete rhizopus l.jpg

Figure 12.20 Life cycle of the zygomycete Rhizopus

Asexual Reproduction

Sexual Reproduction

Zygosporangiummatures.

Nuclear meioses occurs(not shown).

Spore germinatesto produce aseptatemycelium (1n).

Zygosporangiumproduces anasexual sporangium(1n).

Vegetativemyceliumgrows.

Zygosporangiumforms. (2n)

Sporangiumbursts torelease spores.

Mating hyphaejoin and fuse.

Dikaryon(nn)

Spores (1n)are releasedfromsporangium.

Haploid nuclei (1n)

Sporangiospores

Sporangium(1n)

Gameteforms attip ofhypha.

Sporangio-phore

Aerial hyphaproduces asporangium.

Spore germinates.


Figure 12 21 ascocarps fruiting bodies of the common morel morchella esculenta l.jpg

Figure 12.21 Ascocarps (fruiting bodies) of the common morel, Morchella esculenta


Figure 12 22 life cycle of an ascomycete l.jpg

Asexual Reproduction

Sexual Reproduction (called Eupenicillium at this stage)

Hyphal tip undergoescytoplasmic fusion withopposite mating type.

Vegetative myceliumgrows.

Figure 12.22 Life cycle of an ascomycete

Conidiospore germinatesto producemycelium.

Dikaryon (nn)forms.

Nuclei fuse interminal cells toform 2n nuclei.

Conidiosporesare releasedfrom conidiophore.

Dikaryon

Ascosporesgerminateto producemycelia.

Ascus

Ascospores

Conidiospore

Meiosisproducesfour haploid(1n) cells.

Ascusopens toreleaseascospores.

Conidiophore

Hypha producesconidiophores andconidiospores.

Ascus

Ascospore

Mitosis produces eighthaploid ascosporeson each tip.


Figure 12 23 basidiocarps fruiting bodies of the bird s nest fungus crucibulum l.jpg

Figure 12.23 Basidiocarps (fruiting bodies) of the bird's nest fungus, Crucibulum


Figure 12 24 sexual life cycle of amanita muscaria a poisonous basidiomycete l.jpg

Cross section of gillshowing hyphae..

Figure 12.24 Sexual life cycle of Amanita muscaria, a poisonous basidiomycete

Pair of haploidnuclei fuse.

2n

Meiosis producesfour haploidnuclei.

Fourbasidiospores(1n) develop.

Gills

Basidium

Basidiospore isreleased.

Basidiospores germinateto produce mycelia.

Dikaryotic myceliumgrowing in soil produces

basidiocarp (mushroom).

Dikaryon(nn)

Hyphae of opposite matingtypes fuse belowgroundto produce dikaryoticmycelium.


Fungi49 l.jpg
Fungi

Classification of Fungi

Deuteromycetes

Heterogeneous collection of fungi with unknown sexual stages

rRNA analysis revealed that most deuteromycetes belong in the division Ascomycota

© 2012 Pearson Education Inc.


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Fungi

Lichens

Partnerships between fungi and photosynthetic microbes

Abundant throughout the world, particularly in pristine habitats

Grow in almost every habitat

On soil, rocks, leaves, tree bark, other lichens, even tortoises

Occur in three basic shapes

Fruticose, crustose, foliose

Create soil from weathered rocks

Eaten by many animals

© 2012 Pearson Education Inc.


Figure 12 25 makeup of a lichen l.jpg

Figure 12.25 Makeup of a lichen

Ascocarp of fungus

Soredium

Algal cell

Fungal hyphae

Fungal hyphae

Phototrophic layer

Substrate


Figure 12 26 gross morphology of lichens l.jpg

Crustose

Fruticose

Foliose

Figure 12.26 Gross morphology of lichens


Algae l.jpg
Algae

Simple, eukaryotic phototrophs that carry out oxygenic photosynthesis using chlorophyll a

Have sexual reproductive structures

Every cell becomes a gamete

Differ widely in distribution, morphology, reproduction, and biochemical traits

© 2012 Pearson Education Inc.


Algae54 l.jpg
Algae

Distribution of Algae

Most are aquatic

Live in the photic zone of fresh, brackish, and saltwater

Accessory photosynthetic pigments that trap energy of light and pass it to chlorophyll a

© 2012 Pearson Education Inc.


Algae55 l.jpg
Algae

Morphology of Algae

Unicellular, colonial, or have simple multicellular bodies (thalli)

© 2012 Pearson Education Inc.


Algae56 l.jpg
Algae

Reproduction in Algae

Unicellular algae

Asexual reproduction involves mitosis followed by cytokinesis

Sexual reproduction forms zygotes from individual gametes

Zygote undergoes meiosis

Multicellular algae

Reproduce asexually by fragmentation

Reproduce sexually with alternation of generations

© 2012 Pearson Education Inc.


Figure 12 27 alternation of generations in algae as occurs in the green alga ulva l.jpg

Figure 12.27 Alternation of generations in algae, as occurs in the green alga Ulva

Diploid (2n) generation

Meiosis

Zygote

Diploidindividual

Male and femalehaploid spores

Fusion

Malegamete

Male haploidindividual

Femalegamete

Female haploidindividual

Haploid (1n) generation


Algae58 l.jpg
Algae

Classification of Algae

Classification not settled

Classified into groups named for their photosynthetic pigments

© 2012 Pearson Education Inc.


Algae59 l.jpg
Algae

Classification of Algae

Division Chlorophyta

Green algae

Often considered progenitors of plants

© 2012 Pearson Education Inc.


Figure 12 28 antithamnion a red alga l.jpg

Figure 12.28 Antithamnion, a red alga


Figure 12 29 the two types of flagella of the sperm of the brown alga fucus l.jpg

Figure 12.29 The two types of flagella of the sperm of the brown alga Fucus

“Hairy” flagellum

Whiplike flagellum


Figure 12 30 portion of the giant kelp macrocystis a brown alga l.jpg

Pneumocyst

Figure 12.30 Portion of the giant kelp Macrocystis, a brown alga


Figure 12 31 coscinodiscus a diatom l.jpg

Figure 12.31 Coscinodiscus, a diatom


Water molds l.jpg
Water Molds

Differ from fungi in the following ways:

Have tubular cristae in their mitochondria

Cell walls are of cellulose instead of chitin

Spores have two flagella

One whiplike and one tinsel-like

Have true diploid thalli

© 2012 Pearson Education Inc.


Figure 12 32 the important role of water molds in recycling organic nutrients in aquatic habitats l.jpg

Figure 12.32 The important role of water molds in recycling organic nutrients in aquatic habitats


Other eukaryotes of microbiological interest parasitic helminths and vectors l.jpg
Other Eukaryotes of Microbiological Interest: Parasitic Helminths and Vectors

Parasitic worms have microscopic infective and diagnostic stages

Arthropod vectors are animals that carry pathogens

Mechanical vectors

Biological vectors

Disease vectors belong to two classes of arthropod

Arachnida

Insecta

© 2012 Pearson Education Inc.


Other eukaryotes of microbiological interest parasitic helminths and vectors67 l.jpg
Other Eukaryotes of Microbiological Interest: Parasitic Helminths and Vectors

Arachnids

Adult arachnids have four pairs of legs

Ticks are the most important arachnid vectors

Hard ticks are most prominent tick vectors

A few mite species transmit rickettsial diseases

© 2012 Pearson Education Inc.


Other eukaryotes of microbiological interest parasitic helminths and vectors68 l.jpg
Other Eukaryotes of Microbiological Interest: Parasitic Helminths and Vectors

Insects

Adult insects have three pairs of legs and three body regions

Include

Fleas

Lice

Flies

Mosquitoes

Kissing bugs

© 2012 Pearson Education Inc.



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