PROTISTS AND FUNGIChapters 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.

If prokaryotes were the first cells, how did eukaryotes evolve?

Connection to Evolution

Plasma membrane Cytoplasm

Ancestral prokaryote Cell with nucleus and endomembrane system

Endoplasmic reticulum NucleusNuclearenvelope

Aerobic heterotrophicprokaryote

Somecells

Ancestral host cell Photosyntheticeukaryotic cell

MitochondrionPhotosyntheticprokaryote

MitochondrionChloroplast

KINGDOM PROTISTA

DOMAIN EUKARYA

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) Animal-like (Protozoans)2) Plantlike (Algae)3) 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

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 Apicomplexa

AKA: Zooflagellates Use flagella to move Cause American and African sleeping

sicknesses Example: Trypanosoma

Infects a tsetse fly which transmits disease to humans

Kingdom Protista Phylum Zoomastigina

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.

Protists are mainly unicellular. How did multicellular organisms evolve?

Connection to Evolution

Evolution of Multicellular Organisms Multicellular organisms probably evolved

from colonial protist cells becoming specialized

Multicellular life has diversified over hundreds of millions of years

Unicellularprotist

1

Colony

2

Early multicellular organism withspecialized, interdependent cells

Locomotorcells

Food-synthesizingcells

Somaticcells

3

Later organism thatproduces gametes

Gamete

Evolution of Multicellular Organisms

Multicellular life first arose over a billion years ago All life was

aquatic until almost 500 million years ago

Multicellular organismscolonize landDiverse multicellular algae, fungi,and animals, all living in the sea

Mass extinctions

Earliest animals; manymulticellular algae

Oldest known fossils ofmulticellular eukaryotes(small algae)

Earliest multicellular eukaryotes?

Age

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PREC

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BR

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LEO

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KINGDOM FUNGI

DOMAIN EUKARYA

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

discoveredStaphylococcusaureus Penicillium

Zone ofinhibitedgrowth