PROTISTS AND FUNGI
Chapters 19 and 20
Origin of Eukaryotic Cells

Endosymbiotic Theory
 The
eukaryotic cell probably originated as a community
of prokaryotes 2 billion years ago.
 The nucleus and endomembrane system of organelles
probably evolved from infoldings of the plasma
membrane of ancestral prokaryotes.
 Mitochondria and chloroplasts probably evolved from
symbiotic prokaryotes that took up residence inside
larger prokaryotic cells.
Connection to Evolution
If prokaryotes were the first cells, how did
eukaryotes evolve?
Plasma membrane
Cytoplasm
Ancestral prokaryote
Aerobic heterotrophic
prokaryote
Endoplasmic reticulum
Nucleus
Nuclear
envelope
Cell with nucleus and endomembrane system
Mitochondrion
Mitochondrion
Photosynthetic
prokaryote
Chloroplast
Some
cells
Ancestral host cell
Photosynthetic
eukaryotic cell
DOMAIN EUKARYA
KINGDOM PROTISTA
Domain Eukarya Kingdom Protista

Characteristics of a Protist:
 Often
characterized by what they are NOT
 Not animals, plants, or fungi
 Diverse group of 200,000 organisms
 Cell type: EUKARYOTES
 Mode of Nutrition: Heterotrophs and autotrophs
 Habitat: water or moist soil; some live in animals
causing disease
Categorizing Protists
1)
2)
3)
Animal-like (Protozoans)
Plantlike (Algae)
Fungus-like (Slime mold & mildew)
Protozoa

Animal-like heterotrophs

Four Phlya:
 Phylum
Ciliophora: Use cilia for motion
 Phylum Sarcodina: Use pseudopods for motion
 Phylum Apicomplexa: Use spores for motion
 Phylum Zoomastigina: Use flagella for motion
Kingdom Protista Phylum Ciliophora





AKA: Ciliates
Use short, hair-like projections to move through
fluids and move food particles into the cell
7000 species of ciliates
Abundant in oceans, lakes, and rivers
Example: Paramecium caudatum
Kingdom Protista Phylum Sarcodina



Animal-like protists that use pseudopods for feeding
and locomotion
Pseudopod: false foot; a temporary extension of
cytoplasm that surrounds and envelops smaller
organisms, forming a food vacuole
Example: Amoeba
Kingdom Protista Phylum Apicomplexa





AKA: Sporozoans
Produce spores
(reproductive cells)
during their life cycle
Parasitic and move as
their hosts move
Hosts transmit the spores
to new hosts
Example: Plasmodium
(malaria)
Kingdom Protista Phylum Zoomastigina




AKA: Zooflagellates
Use flagella to move
Cause American and African sleeping sicknesses
Example: Trypanosoma
 Infects
a tsetse fly which transmits disease to humans
Algae

Plant-like protists because they contain photosynthetic pigments

Found in bodies of water

Can be unicellular or multicellular


Unicellular Phyla:
 Phylum Bacillariophyta: Diatoms
 Phylum Pyrrophyta: Dinoflagellates
 Phylum Euglenophyta: Euglenoids
 Phylum Chrysophyta: Chrysophytes (colonies)
Multicellular Phyla:
 Phylum Phaeophyta: Brown Algae
 Phylum Chlorophyta: Green Algae
 Phylum Rhodophyta: Red Algae
Kingdom Protista Plant-like Examples

Diatoms
 Unicellular
 Photosynthetic
autotrophs using chlorophyll (green
pigment) and carotenoids (golden pigment)
 Store food as oil, which is less dense that water
 Float near the surface of water where they can absorb
energy from the Sun for photosynthesis
Kingdom Protista Plant-like Examples

Dinoflagellates
 Unicellular
 Have
two flagella at right angles to one another
 Cause the organism to spin as they move through the
water
 Some are photosynthetic autotrophs and others are
heterotrophs
 Some
use red pigment for photosynthesis, which cause red
tides during blooms
 Produce dangerous toxins
Kingdom Protista Plant-like Examples

Green Algae
 Unicellular
and multicellular
 Use chlorophyll for photosynthesis
 Have cell walls and store food as carbohydrates
 Most are found in freshwater
Kingdom Protista Fungus-Like Examples


AKA: Slime molds
Similar to fungus:
Use spores to reproduce
 Feed on decaying organic
matter and absorb nutrients
through their cell walls


Different from fungus:
Fungi cell walls contain chitin, a
complex carbohydrate.
 Slime mold cell walls contain
cellulose.

Connection to Evolution
Protists are mainly unicellular. How did
multicellular organisms evolve?
Evolution of Multicellular Organisms


Multicellular organisms probably evolved from
colonial protist cells becoming specialized
Multicellular life has diversified over hundreds of
millions of years
Gamete
1
Unicellular
protist
2
Locomotor
cells
3
Somatic
cells
Foodsynthesizing
cells
Colony
Early multicellular organism with
specialized, interdependent cells
Later organism that
produces gametes
Evolution of Multicellular Organisms
life was aquatic
until almost 500
million years ago
Multicellular organisms
colonize land
Diverse multicellular algae, fungi,
and animals, all living in the sea
Mass extinctions
Earliest animals; many
multicellular algae
PRECAMBRIAN ERA
 All
PALEOZOIC
ERA
Multicellular life
first arose over a
billion years ago
Age of fossils in millions of years

Oldest known fossils of
multicellular eukaryotes
(small algae)
Earliest multicellular eukaryotes?
DOMAIN EUKARYA
KINGDOM FUNGI
Characteristics of Fungi

Diverse – over 100,000 species have
been identified
 Some
are mutualistic organisms
 Others are parasites
 Some
are predators
 Others
are decomposers of dead
organisms
Characteristics of Fungi



Type of cell: eukaryote
Mode of nutrition: heterotroph
Number of cells:
 Most
are multicellular
 Yeasts are unicellular

Cell structure: cell wall composed of chitin
Unique Fungi Characteristics



Hyphae: long chains of cells;
threadlike filaments that make up
the body of the fungus
Mycelium: netlike mass of
hyphae; sometimes underground
Fruiting body: fungus seen above
ground; example-mushroom
Structure of a Fungus
Nutrition in Fungus

All fungi are heterotrophs, but there are three types
of fungi that differ in how they obtain nutrients.
 Saprophytic
fungi: DECOMPOSER
 Feed
on dead organisms or organic wastes
 Return nutrients to the food chain
 Parasitic
fungi: absorb nutrients from the living cells of
a host organism
 Mutualistic fungi: WORK TOGETHER
 Example:
Soybean root fungus receives sugar from the
soybean root and helps the root to increase water and
mineral uptake.
Phyla of Fungi
1
2
3
4
1. Chytrids are closely
related to protists. The
are unicellular. Earliest
fungi.
2. Common molds are
multicelluar and
composed of stolons on
the surface and rhizoids
that penetrate the surface.
3. Club fungi are the most
commonly recognized
fungus. They are
multicellular.
4. Yeast is unicellular, but
most members are
multicellular.
Ecology of Fungi


Lichens consist of fungi living mutualistically with
photosynthetic organisms.
Lichens are associations of algae or cyanobacteria
with a network of fungal hyphae.
 The
fungus receives food in exchange for housing,
water, and minerals.

Lichen serve as bioindicators or environmental
changes.
Parasitic Fungi

Parasitic fungi cause disease
 Dutch
elm disease
 Corn smut
 Athlete’s foot
Beneficial Fungi



Numerous fungi are beneficial
Many are important in the decomposition of organic
material and nutrient recycling
Fungi are also important as food
 Mushrooms
are the fruiting bodies of subterranean
fungi
 Yeasts (unicellular fungi) are essential for baking and
beer and wine production
 Fungi are used to ripen
certain cheeses
Beneficial Fungi

Penicillin – First antibiotic to be discovered
Staphylococcus
aureus
Penicillium
Zone of
inhibited
growth