Copyright © 2013 Pearson Education, Inc.Lectures prepared by Christine L. Case

© 2013 Pearson Education, Inc. Lectures prepared by Christine L. Case

Chapter 12

The Eukaryotes: Fungi, Algae, Protozoa, and

Helminths

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Kingdom Fungi

Nutritional Type Chemoheterotroph

Multicellularity All, except yeasts

Cellular ArrangementUnicellular, filamentous, fleshy

Food Acquisition Method Absorptive

Characteristic Features Sexual and asexual spores

Mycology: the study of fungi

Fungi

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Table 12.1 Selected Features of Fungi and Bacteria Compared.

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Vegetative Growth

Molds The fungal thallus consists of hyphae; a mass of hyphae

is a mycelium

Unicellular fungi Fission yeasts divide symmetrically Budding yeasts divide asymmetrically

Dimorphism Pathogenic dimorphic fungi are yeastlike at 37°C

and moldlike at 25°C

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Figure 12.2 Characteristics of fungal hyphae.

Septum

Cell wall

PoreNuclei

Septate hypha Coenocytic hypha Growth of a hypha from a spore

Spore

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Figure 12.4 A budding yeast.

Parent cell

Bud

Bud scar

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Figure 12.6a Representative asexual spores.

Conidia

Conidiophore

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Figure 12.6b Representative asexual spores.

Arthrospores

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Figure 12.6c Representative asexual spores.

Pseudohypha

Blastoconidia

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Figure 12.6d Representative asexual spores.

Chlamydoconidium

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Figure 12.6e Representative asexual spores.

Sporangiospores

Sporangiophore

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Sexual Reproduction

Three phases: Plasmogamy: haploid donor cell nucleus (+) penetrates

cytoplasm of recipient cell (−) Karyogamy: + and − nuclei fuse Meiosis: diploid nucleus produces haploid nuclei

(sexual spores)

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Sexual Spores

Zygospore: fusion of haploid cells produces one zygospore

Ascospore: formed in a sac (ascus) Basidiospore: formed externally on a pedestal

(basidium)

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Medically Important Phyla of Fungi

Zygomycota Microsporidia Ascomycota

Anamorphs

Basidiomycota

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Economic Effects of Fungi

Saccharomyces cerevisiae: bread, wine, HBV vaccine

Trichoderma: cellulase Taxomyces: taxol Entomophaga: biocontrol Coniothyrium minitans: kills fungi Paecilomyces: kills termites

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Fungal Diseases (Mycoses)

Systemic mycoses: deep within body Subcutaneous mycoses: beneath the skin Cutaneous mycoses: affect hair, skin, and nails Superficial mycoses: localized, e.g., hair shafts Opportunistic mycoses: caused by normal

microbiota or environmental fungi

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Lichens

Mutualistic combination of an alga (or cyanobacterium) and fungus

Alga produces and secretes carbohydrates; fungus provides holdfast

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Figure 12.11a Lichens.

Three types of lichens

Fruticose

Foliose

Crustose

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Figure 12.11b Lichens.

Lichen thallus

Fungus

Alga

Cortex

Algal layer

Fungalhyphae

Cortex

Rhizine

Medulla

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Economic Effects of Lichens

Dyes Antimicrobial (Usnea) Litmus

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Kingdom Protista

Nutritional Type Photoautotroph

Multicellularity Some

Cellular ArrangementUnicellular, colonial, filamentous, tissues

Food Acquisition Method Diffusion

Characteristic Features Pigments

Algae

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Figure 12.12a Algae and their habitats.

Red 𝛌

Orange 𝛌Yellow 𝛌

Violet 𝛌

Blue 𝛌 Red algae

Multicellulargreen algae

Brown algae

Unicellular green algae,diatoms, dinoflagellates

Sublittoralzone

Littoralzone

Green algae,cyanobacteria,euglenoids

LANDSURFACE

Algal habitats

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Figure 12.12 Algae and their habitats.

Pneumatocyst Blade

Brown alga (Macrocystis)

Stipe

Red alga (Microcladia)

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Figure 12.13a Green algae.

Multicellular green alga (Ulva)

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Figure 12.14a Diatoms.

Eunotia, a freshwater diatom that grows in acidic water

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Figure 12.15 Peridinium, a dinoflagellate.

Flagellum

Flagellum

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Phaeophyta

Brown algae (kelp) Cellulose and alginic acid cell walls Multicellular Chlorophyll a and c, xanthophylls Store carbohydrates Harvested for algin

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Rhodophyta

Red algae Cellulose cell walls Most are multicellular Chlorophyll a and d, phycobiliproteins Store glucose polymer Harvested for agar and carrageenan

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Chlorophyta

Green algae Cellulose cell walls Unicellular or multicellular Chlorophyll a and b Store glucose polymer Gave rise to plants

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Diatoms

Pectin and silica cell walls Unicellular Chlorophyll a and c, carotene, xanthophylls Store oil Fossilized diatoms formed oil Produce domoic acid

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Figure 12.14 Diatoms.

Asexual reproduction of a diatom

Eunotia, a freshwater diatom that grows in acidic water

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Dinoflagellates

Cellulose in plasma membrane Unicellular Chlorophyll a and c, carotene, xanthins Store starch Some are symbionts in marine animals Neurotoxins cause paralytic shellfish poisoning

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Figure 12.15 Peridinium, a dinoflagellate.

Flagellum

Flagellum

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Oomycota

Cellulose cell walls Multicellular Chemoheterotrophic Produce zoospores Decomposers and plant parasites

Phytophthora infestans responsible for Irish potato blight P. cinnamoni infects Eucalyptus P. ramorum causes “sudden oak death”

Water molds

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Kingdom Various

Nutritional Type Chemoheterotroph

Multicellularity None

Cellular Arrangement Unicellular

Food Acquisition Method Absorptive; ingestive

Characteristic Features Motility; some form cysts

Protozoa

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Characteristics of Protozoa

Vegetative form is a trophozoite Asexual reproduction is by fission, budding, or

schizogony Sexual reproduction by conjugation Some produce cysts

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Medically Important Phyla of Protozoa

Diplomonads Parabasalids Euglenozoa Amebae Apicomplexa Dinoflagellates Ciliates

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Amebae

Move by pseudopods Entamoeba Acanthamoeba

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Figure 12.19 Amebae.

Pseudopods

Nucleus

Food vacuole

Amoeba proteus

Entamoeba histolytica

Nucleus

Red blood cells

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Apicomplexa

Nonmotile Intracellular parasites Complex life cycles Plasmodium Babesia Cryptosporidium Cyclospora

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Ciliates

Move by cilia Complex cells Balantidium coli is the only human parasite

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Figure 12.21 Ciliates.

PellicleCytostome

Contractile vacuole Macronucleus MicronucleusAnal pore

Cilia

Food vacuoles

Cilia

Cytostome

Paramecium

Vorticella

Stalk

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Figure 12.17 Conjugation in the ciliate protozoan Paramecium.

Macronucleus

Micronucleus

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Figure 12.23 The life cycle of a plasmodial slime mold.

Plasmodium grows,distributing nutrients bycytoplasmic streaming.

Haploid gametesfuse, producingzygote.

Gametegerminatesfrom spore.

Spores arereleased.

Nuclei in spores go throughmeiosis, forming gametes.

Multinucleateplasmodiumforms.

Zygote developsby nucleardivision andcell growth.

Plasmodium separates into groups of protoplasm.

Each group formssporangia on stalks.

Spores developin sporangia.

Sexualreproduction

Asexualreproduction

Channel ofcytoplasmicstreaming

Sporangia

Stalk

4

2

3

1

56

7

8

9

10

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Kingdom Animalia

Nutritional Type Chemoheterotroph

Multicellularity All

Cellular Arrangement Tissues and organs

Food Acquisition Method Ingestive; absorptive

Characteristic Features Elaborate life cycles

Helminths

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Helminths (Parasitic Worms)

Kingdom: Animalia Phylum: Platyhelminthes (flatworms)

Class: trematodes (flukes) Class: cestodes (tapeworms)

Phylum: Nematoda (roundworms)

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Characteristics of Helminths

Reduced digestive system Reduced nervous system Reduced locomotion Complex reproduction

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Life Cycle of Helminths

Monoecious (hermaphroditic) Male and female reproductive systems in one animal

Dioecious Separate male and female

Egg larva(e) adult

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Figure 12.25 Flukes.

Oral sucker

Intestine

Ventral sucker

Testis

Ovary

Fluke anatomy Clonorchis sinensis

Oral sucker

OvaryIntestine Testes

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Figure 12.26 The life cycle of the lung fluke, Paragonimus, spp.

Cercaria

Redia

Cercaria (0.5 mm long)

Intermediate host

Cercaria leavessnail and enterscrayfish.

Metacercaria(0.25–0.5 mm)

In crayfish, cercariaencysts to producemetacercaria.

Infected crayfish is eaten by human, andmetacercaria develops into adult fluke.

Definitive host

Free-swimmingmiracidiumenters snail.

Intermediate host

Miracidium(0.8 mm long)

Miracidiumdevelopsin egg andhatchesfrom egg.

Eggs reach waterafter being excretedin feces.

Adult fluke(7.5–12 mm long)

Eggs

Inside snail, miracidiumdevelops into redia, whichreproduces asexuallyto produce rediae; severalcercariae develop within redia.

4

2

3

8

5

6

7

1Hermaphroditic adult fluke releases eggs into human lung.

Sexualreproduction

Asexualreproduction

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Humans as Definitive Hosts

Definitive Host Taenia saginata Cysticerci in beef muscle

Intermediate Host

Echinococcus granulosus

Adult in dog

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Adult pinworm

Figure 12.29a The pinworm Enterobius vermicularis.

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Figure 12.30 The heartworm Dirofilaria immitis.

Heartworm

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Adult pinworm

Figure 12.29 The pinworm Enterobius vermicularis.

Mouth

Intestine

Ovary

Genitalpore

Anus

Female(8–13 mm long)

Mouth

Intestine

Genitalpore

Anus

Spicules

Male(2–5 mm long)

Larva

Egg (55 μm long)

Pinworm egg

Testis

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Figure 25.23 An Ancylostoma hookworm attached to intestinal mucosa.

Hookworm

Intestinal mucosa

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Arthropods as Vectors

May transmit diseases (vectors) Kingdom: Animalia

Phylum: Arthropoda (exoskeleton, jointed legs) Class: Insecta (6 legs)

Lice, fleas, mosquitoes Class: Arachnida (8 legs)

Mites and ticks

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Arthropods as Vectors

Mechanical transmission Biological transmission

Microbe multiplies in vector

Definitive host Microbe’s sexual reproduction takes place in vector

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Figure 12.31 Mosquito.

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Figure 12.32 Tick.

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Insert Fig 12.33

Figure 12.33 Arthropod vectors.

2.5 mm

2.5 mm

Rat fleaHuman louse Deer fly Kissing bug

1 cm

2 cm