19.1 Diversity of Protists

KEY CONCEPT

Kingdom Protista is the most diverse of all the

kingdoms.

19.1 Diversity of Protists

Protists can be animal-like, plantlike, or funguslike.

• Protists are eukaryotes that are not animals, plants, or

fungi.

19.1 Diversity of Protists

• Animal-like protists consume other organisms.

– heterotrophs

– single-celled

19.1 Diversity of Protists

• Plantlike protists are photosynthetic.

– single-celled, colonial, or multicellular

– no roots, stems, or leaves

19.1 Diversity of Protists

• Funguslike protists decompose dead organisms.

– heterotrophs

– can move, whereas fungi cannot

19.1 Diversity of Protists

Protists are difficult to classify.

• Protista is one kingdom in the domain Eukarya.

19.1 Diversity of Protists

• Protist classification will likely change.

– Some protists are not closely related.

– Molecular evidence supports reclassification.

19.2 Animal-like Protists

KEY CONCEPT

Animal-like protists are single-celled heterotrophs

that can move.

19.2 Animal-like Protists

Animal-like protists move in various ways.

• Animal-like protists are often called protozoa.

macronucleus

food vacuole

oral groove

micronucleus

contractile vacuole

cilia

19.2 Animal-like Protists

• Protozoa with flagella are zooflagellates.

– flagella help zooflagellates swim

– more than 2000 zooflagellates

19.2 Animal-like Protists

• Some protists move with pseudopods.

– change shape as they move

– amoebas

19.2 Animal-like Protists

– foraminifera

• Some protists move with pseudopods.

–change shape as they move

– amoebas

19.2 Animal-like Protists

• Some protozoa move with cilia.

macronucleus

food vacuole

oral groove

micronucleus

contractile vacuole

cilia

– cilia help protists swim and capture food

– more than 8000 ciliates

19.2 Animal-like Protists

Some animal-like protists cause disease.

• Protists cause some well-

known infectious diseases. sporozoiteshuman liver

liver cells

developed

parasites

red blood

cells

• Malaria is caused by Plasmodium and spread by mosquitoes.

• Sleeping sickness is caused by Trypanosoma and spread by flies.

• A giardia infection is caused by Giardia and spread through water.

Malaria Infection

19.3 Plantlike Protists

KEY CONCEPT

Algae are plantlike protists.

19.3 Plantlike Protists

Plantlike protists can be single-celled or multicellular.

• Photosynthetic plantlike protists are called

algae.

colony

daughter colony

19.3 Plantlike Protists

• Euglenoids are a large group of plantlike protists.

pellicle

nucleus

chloroplast

eye spot

contractile

vacuole

flagellum

– mostly photosynthetic

– some heterotrophic

– single-celled

– one or two flagella

19.3 Plantlike Protists

• Dinoflagellates are mostly marine plantlike protists.

Dinoflagellates

– have two flagella

– may be bioluminescent

– have stiff protective plates

– can cause red tide

19.3 Plantlike Protists

• Diatoms are plantlike protists with glasslike shells.

– shells made of silica

– produce large amounts of oxygen

19.3 Plantlike Protists

• Multicellular algae are classified by their pigments.

– Green algae contain

chlorophyll a and b.

– Brown algae contain

chlorophyll c.

– Red algae contain

chlorophyll a and

phycoerythrin.

19.3 Plantlike Protists

Many plantlike protists can reproduce both sexually and

asexually.

• All algae can reproduce asexually.

– Multicellular algae can fragment.

– Chlamydomonas divides into zoospores.

19.3 Plantlike Protists

• Some algae produce sexually.

– Some species alternate generations.

– Sexual reproduction can be triggered by environmental

stress.

19.4 Funguslike Protists

KEY CONCEPT

Funguslike protists decompose organic matter.

19.4 Funguslike Protists

Slime molds and water molds are funguslike protists.

• Slime molds have both funguslike and animallike traits.

– decomposers, like fungi

– can move, like animals

19.4 Funguslike Protists

• Slime molds can be plasmodial or cellular.

– Plasmodial slime molds are giant cells with many nuclei.

– Cellular slime molds contain independent cells.

19.4 Funguslike Protists

• Water molds are freshwater, funguslike protists.

– one type of water mold caused Great Potato Famine

of Ireland in the 1800’s

– made of branching

strands of cells

– can be parasites of

plants or fish

19.5 Diversity of Fungi

KEY CONCEPT

Fungi are heterotrophs that absorb their food.

19.5 Diversity of Fungi

Fungi are adapted to absorb their food from the

environment.

• Plants and fungi have different traits.

– Fungal cell walls are made of chitin.

– Plant cell walls are made of cellulose.

– Plants have chlorophyll and photosynthesize.

– Fungi absorb food through hyphae.

19.5 Diversity of Fungi

• Fungi are multicellular organisms, with the exception of

yeasts.

– hyphae

– mycellium

– fruiting body

19.5 Diversity of Fungi

Fungi come in many shapes and sizes.

• Primitive fungi are aquatic and have flagellated spores.

• Sac fungi form a reproductive sac, or ascus.

– Yeasts are single-celled sac fungi.

– Morels and truffles are multicellular sac fungi.

19.5 Diversity of Fungi

• Bread molds are often found on spoiled food.

– form zygospores during reproduction

– mycorrhizae belong to this group

19.5 Diversity of Fungi

• Club fungi have fruiting bodies which are club-shaped.

– reproductive structures

called basidia

– include mushrooms,

puffballs, and

shelf fungi

19.5 Diversity of Fungi

Fungi reproduce sexually and asexually.

• Most fungi reproduce both sexually and asexually.

– Yeasts reproduce asexually through budding.

– Yeasts form asci during sexual reproduction.

19.5 Diversity of Fungi

• Multicellular fungi have complex reproductive cycles.

– distinctive reproductive

structures

19.5 Diversity of Fungi

– life cycles may include either sexual or asexual reproduction or both

• Multicellular fungi have complex reproductive cycles.

19.5 Diversity of Fungi

– life cycles may include either sexual or asexual reproduction or both

• Multicellular fungi have complex reproductive cycles.

19.5 Diversity of Fungi

• All fungi form spores and zygotes.

19.6 Ecology of Fungi

KEY CONCEPT

Fungi recycle nutrients in the environment.

19.6 Ecology of Fungi

Fungi may be decomposers, pathogens, or mutualists.

• Fungi and bacteria are the main decomposers in any

ecosystem.

– decompose dead leaves, twigs, logs, and animals

– return nutrients to the soil

– can damage fruit trees and wooden structures

19.6 Ecology of Fungi

• Fungi can act as pathogens.

– human diseases include ringworm and athlete’s foot

– plant diseases include Dutch elm disease

19.6 Ecology of Fungi

• Fungi can act as mutualists.

– lichens form between fungi and algae

– mycorrhizae form between fungi and plants

19.6 Ecology of Fungi

– relationships form between fungi and some insects

• Fungi can act as mutualists.

19.6 Ecology of Fungi

Fungi are studied for many purposes.

• Fungi are useful in several ways.

– as food

– as antibiotics

– as model systems for molecular biology