Learning Objectives

Explain the endosymbiotic theory and evidence supporting it

Describe identifying characteristics of the kingdom Protista

Classify the different phyla of protistsCompare and contrast the structure and function of

different protists

Kingdom Protista

•Infolding of membrane system forming nucleus and ER•More surface area for material exchange with envi.

Origin of Eukaryotes – Formation of Nucleus

Endomembrane infolding

Animal Cell

Plant cell

Eukaryotic Evolution -Endosymbiosis HypothesisWhat’s the story?•A prokaryote ingested some aerobic bacteria. The aerobes were protected and produced energy for the prokaryote. Over time the aerobes became mitochondria, no longer able to live on their own.•Some prokaryotes also ingested cyanobacteria, which can photosynthesize. Cyanobacteria became chloroplasts, unable to live on their own

Scientific Evidence for Endosymbiosis theory Membranes of chloroplasts and mitochondria are similar to

those of living prokaryotes

Mitochondria and chloroplasts have their own ribosomes that more similar to prokaryotic ribosomes than ribosomes found in eukaryotes

These organelles reproduces by binary fission within the cell

Mitochondria and chloroplasts have their own DNA that match living prokaryotes’ DNA. Chloroplast genes match genes of cycnobacteria (prokaryotes)

Endosymbiosis doesn’t explain how multicellarity came about

Protists - General CharacteristicsMost are single-celled,

some multi-cellular (algae)

All are eukaryoticCan be heterotrophic or

autotrophicSome have cell walls Some are motileMost live in water, some

live in moist soil or even the human body

Classification and Phylogeny

3 main groups of Protists

Characterized by how they move and get their nutrients.

ProtozoaMeans “first animals”Scavengers or

predatorsHeterotrophssome are parasitesMotileMost live as single cells

but others form coloniesVary in shape and size.

Animal-Like Protists

Protozoa PhylaProtozoa are classified into four phyla based

on their methods of locomotion:

Animal-Like Protists

1. Zoomastigina (Flagellates) one or more flagella (whip-like tail)

rotateSome are parasites, some are

mutalistic symbionts or some are free-living.

Most symbionts live in digestive systems and help the host animals break down cellulose (win-win situation b/t flagellates and termite)

Animal-Like Protists

2. Sarcodines the amoebae No cell wall can change shapeproduce pseudopods (false feet) for

movement and to engulf their prey (extensions of their cytoplasm)

Intestinal amoebas in human cause chronic diarrhea

Animal-Like Protists

Amoeba’s lunch: http://www.youtube.com/watch?v=pvOz4V699gk

3. Ciliates/CiliophoraEx. parameciumHave cilia, tiny

hair-like projections that beat together in rhythm for locomotionCan also move food into the gullet, which leads to a food vacuole.

Balantidium coli –in human intestine Diarrhea

Animal-Like Protists

4. SporozoansProduce sporesPassive movement

(none)parasites Plasmodium vivax

causes one type of malaria in humans.

Animal-Like Protists

Life Cycle of Malaria-causing PlasmodiumWatch: http://highered.mcgraw-hill.com/olc/dl/120090/bio44.swf

AlgaePlant-Like Protists

AlgaeSimple, aquatic, plant-like

organisms that contain chlorophyll

Lack the leaves, roots, stems and water-conducting tissues of plants

Range in size (single cells to giant seaweeds 60 m in length)

Plant-Like Protists

•Algae - not a proper taxonomic group – there are algae in plantae & bacteria kingdom.•Classified into six different Protist “algae” phyla.

6 Algae Phyla

Major producers in food web

MulticellularPlant-like Protists

UnicellularPlant-like Protists

Protists in global carbon cycle

algal bed and reefs contribute the largest % of net primary production on Earth, combining productivity in both ocean and aquatic envi.

Protists play a vial role in C cycling_______________________________________________________________________

__________________________________________________________________________________________________________________________________________

Take away message from this graph?

1. Green algae (Chlorophytes) In freshwater, even sloth’s fur cell walls contain cellulose Ex. Spirogyra (picture)

Multicellular, Plant-Like Protists

2. Brown Algae (Phaeophytes):- in cold water.- cell walls made of cellulose - commonly called seaweeds (ex. kelp) . - Have holdfasts to anchor body on rocky surfaces

3. Red Algae (Rhodophytes):•found in warm seawater. •Red because its pigments absorb green, violet and blue light which penetrate the furthest in water, allowing red algae to live at great depths.•SUSHI! & Agar for bacterial growth

Rhodophytes (red algae)

4. Diatoms (Chrysophytes)most abundant algae in the oceans rigid cell walls contain silica (sand & glass) big component of plankton major source of atmospheric oxygenMain producers of aquatic food webs

Unicellular, Plant-Like Protists

5. Dinoflagellates (Pyrophytes) Photosynthetic; mostly marine stiff cellulose protective coats Have two distinct flagellae in life cycle Numerous; important base for marine food chains Contain toxins (build up in shellfish that eat them). Phosphorescent (photosynthetic pigment):form “red

tides”

6. Euglenoids (Euglenophytes)•Freshwater; have chloroplasts•One large anterior whip-like flagella •Eat smaller organisms if no sun; Eyespot to find sunlight•Reproduce via mitosis

Slime and Water Moulds

Have the characteristics of fungi, protozoa and plants.

Glide from place to place and ingest food like protozoa.

Cellulose in their cell walls like plants.

Also absorb nutrients from their environment like fungi (nutrients from the dead)

Fungi-Like Protists

1. Water Moulds (Phylum Oomycota)

Ex. Water moulds, white rusts and downy mildews.

Filamentous, resemble fungi

Most live as saprotrophs on dead organic materials, but some are parasitic on plants, insects and fish.

Extend fungus like threads into their host where they release digestive enzymes and absorb the nutrients.

The cause of the Irish Potato Famine.

Fungi-Like Protists

2. Plasmodial Slime Moulds (Phylum Myxomycota)

visible to the naked eye as tiny slug like organisms that creep over damp, decaying plant material in forests and fields.

This blob, called a plasmodium, contains many nuclei.

Feed in a similar manner to amoebae.

Spores form in improper living conditions.

Fungi-Like Protists

Dog vomit slime mould

3. Cellular Slime Moulds (Acrasiomycota)

exist as individual amoeboid like cells with one nucleus each.

Feed by ingesting tiny bacteria or yeast cells.

When food becomes scarce, the cells release a chemical that causes them to gather together to form a pseudoplasmodium.

This is a jelly-like mass, which produces a sporangia that releases spores.

Fungi-Like Protists

Protists’ modes of reproduction

Via binary fission Involves conjugationAlternation of generation

(multicellular protists)

Asexual Sexual

Paramecia

Results: 2 genetically identical paramecia daughter cells

Results of conjugation: Two cells exchanged their genetic materials

Multicellular Protists’ Reproduction Sexual reproduction involves formation of gametesGametes are haploid (half the usual # of chromosomes)When a sperm meets an egg, a zygote is formed having full set of chromosomesZygotes are thus diploid (full set of chromosomes)

Multicellular protists can alternate between a diploid and a haploid stage called Alternation of generations

Both diploid and haploid stages are required for the life cycle to be completed in such protists

Brown algae’s alternation of generation life cycles

(Diploid)

(is Haploid, multicellular)

Watch Alternation of generations Green algae: http://kisdwebs.katyisd.org/campuses/MRHS/teacherweb/hallk/Teacher%20Documents/AP%20Biology%20Materials/Diversity/Alternation%20of%20Generation/28_A01s.swf

Summarize Brown algae’s alternation of generation-Large brown algae is a diploid sporophyte-Sporophyte produces single-celled, haploid spores-Spores then grow into multicellular, haploid gametophytes-Gametophytes will produce haploid sperms and eggs-When a sperm is fused with an egg, a diploid zygote is formed which later grow into a multicellular sporophyte (i.e. the large brown algae).

Watch: http://www.youtube.com/watch?v=-zsdYOgTbOk

Recap and review (HW if not done in class):

Q1: How is protista different from kingdom archaea and bacteria?A:

Q2: How is protista different from kingdom fungi?A:

Q3: How is protista different from kingdom plantae?A:

Q4: How is protista different from kingdom animalia?A:

Watch: http://www.youtube.com/watch?v=-zsdYOgTbOk

Recap and review (Cont.)

Q5: Three modes of nutrition of protists?A:

Q6: Your friend one day claims that malaria can be effectively treated with antibiotics. Do you think so too? Why or why not?A:

Q7: Use today’s lesson note to summarize the importance of protists (i.e. their benefits and harms to us)

Q8: What are some implications of climate change, particularly ocean acidification and change in global temperature, on the livelihood of the marine protists and the spread of malaria?

Recap and review (Cont.)

Q9: Research the following about African sleeping sickness:-What causes it?-How is it spread?-What are the symptoms?-How can it be treated?