Download 19.1 Diversity of Protists

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
contractile vacuole
food vacuole
oral groove
micronucleus
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
• Some protists move with pseudopods.
–change shape as they move
– amoebas
– foraminifera
19.2 Animal-like Protists
• Some protozoa move with cilia.
– cilia help protists swim and capture food
– more than 8000 ciliates
macronucleus
contractile vacuole
food vacuole
oral groove
micronucleus
cilia
19.2 Animal-like Protists
Some animal-like protists cause disease.
• Protists cause some wellhuman liver
known infectious diseases.
• 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.
sporozoites
liver cells
developed
parasites
red blood
cells
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.
– mostly photosynthetic
– some heterotrophic
– single-celled
pellicle
contractile
– one or two flagella
vacuole
nucleus
flagellum
chloroplast
eye spot
19.3 Plantlike Protists
• Dinoflagellates are mostly marine plantlike protists.
– have two flagella
– may be bioluminescent
– have stiff protective plates
– can cause red tide
Dinoflagellates
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
• Multicellular fungi have complex reproductive cycles.
– life cycles may include either sexual or asexual
reproduction or both
19.5 Diversity of Fungi
• Multicellular fungi have complex reproductive cycles.
– life cycles may include either sexual or asexual
reproduction or both
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
• Fungi can act as mutualists.
– relationships form between fungi and some insects
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