3 rd Kingdom: Protista Chapter 20, page 497 zsdYOgTbOk

3rd Kingdom: ProtistaChapter 20, page 497

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

What is a protist?

A protist is any eukaryote that is not a plant, animal, fungi.

A. B. C.

D.E.

F.

Protista - the “very first” eukaryotes that appeared on earth over 1.5 billion years ago.

• Eukaryotic• Most are unicellular• Aquatic (fresh and salt)• Reproduce asexually by binary fission and some

are capable of conjugation

Classifying Protists

Protists are classified based on the way they get their food:

A. Animal-like , sometimes called Zooplankton)

B. Plant-like (uniceller and multicellular algae) C. Fungus-like (slime mold and water mold)

Animal-like protists, protozoa, are classified into phyla based on their mode

of locomotion (the way they move)

a) Zooflagellates – use flagellab) Sarcodines – use pseudopodsc) Ciliates – use ciliad) Sporozoans - can’t move on their own and

are parasitic

a) Phylum Zoomatigina (Zooflagellates)

• Propelled by flagella (long whip-like projections). Most have one or two although some have many.

• Most absorb food through their cell membranes

• Many live in lakes or streams, some live in other organisms.

• Most reproduce asexually by binary fission.

Zooflagellates

Zooflagellates

• http://www.youtube.com/watch?v=9duvzqvVflw

• http://www.youtube.com/watch?v=QGAm6hMysTA

b) Phylum Sarcodina (also called Amoeboid)

• No definite shape (Their shape keeps changing depending on their movement).

• Possess pseudopods for feeding and movement (false feet). The cytoplasm of the cell streams into the pseudopod and the rest of the cell follows. This is called amoeboid movement.

• http://www.youtube.com/watch?v=7pR7TNzJ_pA

• Engulf food by phagosytosis . Food vacuoles then form to carry the food.

http://www.youtube.com/watch?v=W6rnhiMxtKUhttp://www.youtube.com/watch?v=pvOz4V699gk

• Some produce shells that contain silica or calcium carbonate.

• Most are free living; some are parasitic.

• Reproduce asexually by binary fission

• In hypotonic solution therefore need contractile vacuoles (explain)

http://www.youtube.com/watch?v=iG6Dd3COug4 http://www.youtube.com/watch?v=mTXRcbjuYGU

Example of Phylum Sarcodina

• Amoeba proteus

See diagrams on boardand on page 500 or yourtext.

c) Phylum Ciliophora (ciliates)

• Many short hair-like projections called cilia for locomotion and feeding

• Has a macro and a micro nucleus.

• Reproduce by binary fission. Undergo conjugation when stressed.

Example of a ciliate (Phylum Ciliophora)

• Paramecium caudatum • Slipper-shaped• Move in one direction at a time and have a

rigid shape• All cilia are co-ordinated• Respond to stimuli, like food, by detecting

chemicals in water.

• Use cilia to capture food, sweeping it into their oral grooves and then into their gullets. A food vacuole is formed.

• Food vacuole pinches off and moves into the cytoplasm. Enzymes enter and the food is digested and absorbed as the vacuole moves along.

• Undigested material is removed from the paramecium when the food vacuole fuses with the cell membrane at the anal pore.

Paramecium eating

See diagrams on board

Paramecium eating pigmented yeast - YouTube

Parmecium caudatum – (conjugation)

• In conjugation, Parmecia will join at their oral grooves. The macro nucleus disintegrates and the micronucleus undergoes division (mitosis), creating 2 identical micronuclei. One of the nuclei will transfer to the other paramecium and fuse with the one still there. Once the two paramecia separate, each will form a new macronucleus.

Paramecia and binary fission

• http://www.youtube.com/watch?v=vnlkvquWXS8&feature=fvwrel

d) Sporozoans

• Sporozoans do not move on their own and are parasitic.

• Many have life cycles that involve more than one host.

• Some Sporozoans cause serious illness like malaria and African sleeping sickness.

• See text pages 503 and 504 (Know the life cycle of the Plasmodium).

• Plasmodium - Human host

• Plasmodium - Mosquito Host

Examples of Sporozoan

•Malaria is one of the world’s most serious infectious diseases, killing as many as 2 million people each year.

• The sporozoan Plasmodium, which causes malaria, is carried by the female Anopheles mosquito.

Plasmodium Life-Cycle

• A pregnant female Anopheles mosquito bites a human infected with malaria and picks up Plasmodium gamete cells.

• In the mosquito, the gametes fuse to form zygotes, which in turn, produce sporozoites which move to the mosquito’s salivary glands.

• The mosquito bites another human and the sporozoites enter that human’s bloodstream.

• Eventually they enter liver cells in the where they reproduce asexually.

• The infected liver cells burst, releasing Plasmodium cells called merozoites that infect red blood cells.

• Merozoites reproduce asexually inside red blood cells.

• Infected red blood cells burst, releasing merozoites that infect other red blood cells. Some cells release gametes that can infect mosquitoes.

Homework

• Answer questions 1 to 6 on page 505• Read pages 506 to 509

B. Plant-like Protists (algae)

• Autotrophs – contain chloroplasts, make food

by photosynthesis

• Store food as carbohydrates

• Major producers of O2

• Major food source in the ocean

• Classified according to:

- pigmentation

- contents of cell walls

- unicellular or multicellular

• We will look at 4 unicellular, plant-like protists and 3 multicellular plant-like protists

Four Phyla of unicellular plant-like Protista:

1) Phylum Euglenophyta (Euglenophytes)

• Have chloroplasts but can also eat food

• Reproduce by binary fission

• Have 2 flagella (1 long and 1 short)

• No cell wall but have a cell membrane called a pellicle

• The pellicle is folded into ribbon-like ridges, each ridge supported by microtubules.

• The pellicle is tough and flexible so the Euglena can crawl through mud.

Genus Euglena

See board and page 507 in text for labelled diagram

YouTube - Euglena in Darkfield at 100X, 200X and 400X

• Food enters the gullet and is absorbed by phagocytosis to form a food vacuole.

• Eyespot (red) can detect light intensity and will direct the cell to swim toward the light (photosynthesis will occur)

• Contractile vacuole collects the H2O entering by osmosis (hypotonic solution in cell). The vacuole will then rupture, releasing the water into the environment through a pore.

2) Phylum Chrysophyta

• Golden algae• gold and brown

pigments dominate• Store food as oil, not

starch• Cell wall is made of

pectin ( a complex carbohydrate)

• Reproduce both sexually and asexually

3) Phylum Bacillariophyta (diatoms)

• Like Chrysophyta, often have a golden brownish pigmentation.

• Cell walls are thin and delicate and made of silica, the main component of glass. They do not break down but collect on the ocean floor.

• Used to make toothpaste, silver polish, some detergents

• Come in many shapes

4. Phylum Pyrrophyta (dinoflagelates)

• About ½ are photosynthetic; other 1/2 heterotrophic

• Most have 2 flagella which they wrap around themselves in grooves between 2 thick plates of cellulose.

• Reproduce asexually by binary fission• Produce light in the ocean,

“bioluminescence”—eerie glow

• Red tide images

Ecology of plant-like protists:

• Phytoplankton- – Small photosynthetic protists that live near

the surface of the ocean.–Carry out ½ the photosynthesis on the

earth– Food source (at the bottom of many food

webs)

• Algae blooms– Often huge numbers of certain algae where

sewage is discharged.– Sometimes there are just too many (blooms) and

they have harmful effects on the environment (The dead algae rob the water of oxygen)

– Other blooms called fire algae cause “red tide” which is toxic to many organisms (Does not harm the shellfish that eats them but the toxins collect in the digestive system of the shellfish and are harmful to anything that eats them.)

Plant-like protists – multicellular algae - 3 phyla

1. Red Algae (Phylum Rodophyta)- are able to live at great depths- contain chlorophyll a and reddish accessory

pigments that allow them to absorb and use light from the “blue” spectrum.

- live in most of the world’s oceans and play an important role in providing nutrients and maintaining ecosystem equilibrium.

6. Rhodophyta (red algae)

2. Brown algae (Phylum Phaeophyta)- contain chlorophyll a and c and a brown

accessory pigment- dark, yellowy colour- cool coastal waters or arctic- giant kelp, fucus which has a holdfast and

leaves with bladders

Examples of Phaeophyta

Dulce Kelp

3. Green algae (Phylum Chlorophyta)- very plant-like with cellulose in their cell

walls, chlorophyll a and b and food stored as starch.- found in fresh and salt water and moist areas

of land-

Slime molds

• The intelligent slime molds

• One man's life's work

Fungus-like Protista (Slime Molds)

• Slime molds are fungus-like protists that absorb nutrients from dead or decaying matter.

• They are not in the Kingdom Fungi because they do not have centrioles and they do not have chitin in their cell walls.

There are two broad classifications of slime molds: cellular slime mold & acellular slime mold.

Both cellular and acellular slime molds start out looking and acting like amoeba. Cellular and acellular slime molds are different from each other in that, in all stages of its life cycle, the cells in cellular slime mold remain distinct. In acellular slime molds, at one stage in their life cycles, their cells fuse together to form one cell with many nuclei.

• Cellular slime mold (page 516) :• Free-living cells that look and act like amoebas. • When there is lots of food, cellular slime mold cells

reproduce sexually (cells of opposite mating types fuse to form a diploid zygote). • In adverse conditions, the cells send out a chemical

signal that attracts thousands of other cells. • These cells form a colony of independent cells that

move slowly, like a slug, for several centimeters• The colony stops and produces a fruiting body that

contains spores. • Each spore can become a cellular slime mold cell

and the cycle starts again.

Life Cycle of Cellular Slime Mold

• Acellular slime mold:– Start out the same way as cellular slime molds– When these cells gather together (aggregate),

they fuse together forming one structure with many nuclei called a plasmodium. (plural: plasmodia)

– A plasmodium may be as large as several meters in diameter.

– The plasmodium produces fruiting bodies which will ultimately produce haploid spores which produce haploid cells. The cells then reproduce sexually and the cycle begins again.

Life Cycle of Acellular Slime Mold