Protists

Chapter 19.

Daily Objective 4/22

• Become familiar with Kingdom Protista, specifically Algae: Plantlike Protists

Kingdom Protista

• Kingdom Protista contains the most diverse organisms.

• Protist’s may be unicellular, multi-cellular, microscopic or large, heterotrophic or autotrophic.

• The only characteristic that all Protist’s share is that they are eukaryotic.

Protist Video Intro

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

Three Main Groups of Protist• Protozoa- animal-like protists, all are unicellular– Protist cause diseases such as malaria, sleeping sickness

and result in million of deaths per year.• Algae- plant like protists, all are photosynethetic– Unicellular algae produce much of the oxygen in the

Earth’s atmosphere and are the basis of aquatic food chains.

• Fungus- like protist, all decomposers– Slime molds and water molds decompose organic

materials and return nutrients to the soil.

1. Fungus-like Protists

• Heterotrophic organisms that decompose organic matter to obtain energy

• Three phyla– Phylum Myxomycota– Phylum Acrasiomycota– Phylum Oomycota

1. Phylum Myxomycota- Plasmodial Slime Mold

• Named due to the formation of a plasmodium– Plasmodium is a mass of cytoplasm that

contains many diploid nuclei but no cell wall or membrane.

– Creates a slimy, multi-nucleate mass that creeps like an amoeba over decaying surfaces and engulfs microscopic organism digesting them in food vacuoles.

• Undergo meiosis when moisture or good become scarce to form spores, which are dispersed into the wind.

2. Phylum Acrasiomycota- Cellular Slime Molds • Spend part of their life

cycle as independent amoeboid cell that feeds, grows and divides by cellular division.

• When food become scarce, the independent cells join with hundreds or thousands of others to reproduce, unlike the plasmodium, these cells have distinct cell membranes

3. Phylm Oomycota- Water molds and downy mildews

• Large and diverse group of fungus-like protists that live in water or moist places

• Water molds appear as fuzzy, white growths on decaying matter, much like fungus.

• They are not classified with fungi because they produce flagellated reproductive cells– The downy mildew, Phytophthora

infectans, was responsible for the potato famine in Ireland from 1845-1847

2. Algae:Plantlike Protists

• Algae are photosynthetic protists that produce more than half of the oxygen in the atmosphere.

• Diversity of Algae- 6 Phylums1. Phylum Euglenoids 2. Phylum Bacillariophyta 3. Phylum Dinoflagellata 4. Phylum Rhodophyta5. Phylum Phaeophyta 6. Phylum Chlorophyta

1. Phylum Euglenoids- Euglena

• Unicellular, aquatic protist with both plant and animal-like characteristics

• They contain photosynthetic pigments and can photosynthesize

• When light is not available they can be heterotrophic and ingest food.

2. Phylum Bacillariophyta- Diatoms

• Unicellular, photosynthetic• Shell composed of silica

(glass-like)• Reproduce sexually and

asexually• Deposits of dead diatoms

collect in the ocean sediments, used as abrasives in toothpaste, metal polishes, make-up, and paint.

3. Phylum Dinoflagellata- Dinoflagellates

• Unicellular, photosynethic with cell walls composed of cellulose

• Have two flagella that casue the protist to spin while moving

• Some are bioluminescent• Several species produce toxins– Gonyaulax catanella, produces

an extremely strong nerve toxin that can be lethal.-

– creates red tide, a dangerous condiotion in the summer when there are population explosions. As many as 40-60 million per liter of water.

4. Phylum Rhodophyta- Red Algae • Multicellular, photosynethic

seaweeds• Body of seawed called a thallus– Lacks roots, stems and leaves;

have holdfasts to attach to rocks. • In addition to chlorophyll,

contain pigments that absorb green, violet and blue light and can therefore live in deep waters.

5. Phylum Phaeophyta- Brown Algae

• Multicellular, photosynethetic algae, composed of yellowish-brownish pigments.

• Almost all are marine• Some also have air bladders

that help them float near surface when light is available

• Kelp is the largest and most complex– Kelp forms dense, underwater

forests that provide a rich habitat for marine organisms.

6. Phylum Chlorophyta- Green Algae

• Unicellular colonial (many single-celled living together) or multicelluar photosynthetic algae with mostly chlorophyll and yellow pigments

• Most live in freshwater; some live in moist soil, and tree trunks

• Examples- Spirogyra-multicellular slender filaments. Volvox- colonial spheres

• Reproduce asexullay by fragmentation, an individual breaks up into pieces and each piece grows into a new individual

• Reproduce sexually by forming spores

3.Diversity of Protozoans• Grouped according to their method of locomotion. • Four main groups of Protozoans (animal-like)

Amoebas Flagellates Ciliates Sporozoans

-No cell wall -Form pseudopodia to move and feed by engulfing their prey-live in aquatic enviornments-asexually reproduceIe. Foraminifera’s and radiolarians, cause African Sleeping Sickness

-one or more flagella used for locomotion-many cause disease although some are helpful.i.e. termites

-Covered in cilia used in locomotion.-Asexual reproduction and sexual reproduction--i.e paramecium

-produce spores (reproductive cell that forms without fertilization)-all are parasites and have one or more hosts-complex lifecyclesi.e. plasmodium (causes malaria)

Sporozoans: Plasmodium

• Malaria LifeCycle• http://www.youtube.com/watch?v=szlfndj0TF

E

Alternation of Generations • The life cycles of some algae's and all plants have a

pattern of reproduction called the alternation of generations (A of G). The organism alternate between a haploid form (n=one copy of the chromosomes) in the gametophyte stage in which the organism produced gametes (male and female sex cells) and the sporophyte form of the organism in which the organisms produced spore cells (2n=two copies of the chromosomes) that form into a new organism. The organism alternates between sexual and asexual reproduction.

• (Using figure 19.21 pg. 560 Draw the A of G with descriptions at each stage )