Protists

KEY CONCEPT Kingdom Protista is the most diverse of all the kingdoms.

Protists

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

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

Protists

• Animal-like protists consume other organisms.

– heterotrophs – single-celled

Protists

• Plantlike protists are photosynthetic.

– single-celled, colonial, or multicellular– no roots, stems, or leaves

Protists

• Funguslike protists decompose dead organisms.

– heterotrophs – can move, whereas fungi cannot

Protists

Protists are difficult to classify.

• Protista is one kingdom in the domain Eukarya.

Protists

• Protist classification will likely change.

– Some protists are not closely related.– Molecular evidence supports reclassification.

Protists

KEY CONCEPT Animal-like protists are single-celled heterotrophs that can move.

Protists

Animal-like protists move in various ways.

• Animal-like protists are often called protozoa.

macronucleus

food vacuole

oral groove

micronucleus

contractile vacuole

cilia

Protists

• Protozoa with flagella are zooflagellates.

– flagella help zooflagellates swim – more than 2000 zooflagellates

Protists

• Some protists move with pseudopods.– change shape as they move – amoebas

Protists

– foraminifera

• Some protists move with pseudopods.– change shape as they move – amoebas

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

Protists

Paramecia have contractile vacuoles to expel excess water. To avoid an obstacle, they back up, and move away in an avoidance reaction.

Protists

Some ciliates remain attached to a surface. Stentor is an example.

Protists

Some animal-like protists cause disease.

• Protists cause some well-known infectious diseases.

sporozoiteshuman liver

liver cells

developedparasites

red bloodcells

• 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

Protists

Trypanosoma

Protists

Giardia

Protists

Trichonympha lives with termites, digests wood. • Both species benefit, so this is called mutualism.

Protists

Algae are plantlike protists.Plantlike protists can be single-celled or multicellular.

• Photosynthetic plantlike protists are called algae.

colonycolony

daughter colonydaughter colony

Protists

Volvox daughter colonies leaving the mother colony.

Protists

• Euglenoids are a large group of plantlike protists.

pellicle

nucleus

chloroplast

eye spot

contractilevacuole

flagellum

– mostly photosynthetic – some heterotrophic – single-celled – one or two flagella

Protists

• Euglena moves toward the light, which is known as a positive phototropism.

• Has a red eyespot, which is light sensitive

Protists

• Dinoflagellates are mostly marine plantlike protists.

DinoflagellatesDinoflagellates

– have two flagella – may be bioluminescent – have stiff protective plates – can cause red tide

Protists

Noctiluca scintillans

Protists

• Diatoms are plantlike protists with glasslike shells.

– shells made of silica – produce large amounts of oxygen

Protists

More diatoms

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.

Protists

Red algae is used to make agar, food thickener, and medicine capsules.

Protists

Spirogyra : a type of green algae

Protists

Slime molds and water molds are funguslike protists.

• Slime molds have both funguslike and animal-like traits.– decomposers, like fungi – can move, like animals

Protists

• Slime molds can be plasmodial or cellular.

– Plasmodial slime molds are giant cells with many nuclei.– Cellular slime molds contain independent cells.

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