Kingdom Protista

1. Kingdom Protista Learning Outcome B1

2. Characteristics • Appeared in the fossil record 1.5 billion years ago • Protistshave an evolutionary advancement over bacteria, because they have a membrane-bound nucleus. • Protistsalso have ribosomes, mitochondria and lysosomes • Protistsare classified within the DomainEukaryaand Kingdom Protista • Generally microscopic and unicellular • Live in fresh/salt water and shady moist terrestrial environments • Example– plankton

3. Characteristics • Plankton is one of the most important producers and consumers in the food chain • Plant-like protists are heterotrophs, which are organisms that must consume food and • Can not make their own food. • Phytoplankton are photosynthetic autotrophs

4. Protist Diversity • There are three major groups: • Plant-like protists • Animal-like protists • Plant-like protists

5. Examples of Plant-like Protists PhylumEuglenophyta • Example – Euglena

8. Characteristics of the Phylum Euglenophyta • Found mainly in fresh water, especially stagnant water • Over 800 species in lakes and pont • Obtain food via photosynthesis, but during periods of darkness they become heterotrophic (take in food) • Have two distinguishing characteristics: eyespot and flagellum • The eyespot has photoreceptors and plays a role in the organisms sensory motor system • Eyespot allows movement towards or away from light

9. Characteristics of Phylum Euglenophyta • Flagellum is used to propel organism through aquatic environments in a whip-like fashion. • Have large green chloroplasts and central vacuole • Food is stored as starch granule just like in land plants • Reproduce asexually; following nuclear division the rest of the cell divides lengthwise • This is known as longtitudinal fission, this involves a growth in cell circumference while the organelles are duplicated. • During unfavourable conditions Euglena may form thick resting cells similar to an endospore

10. Examples of Plant-like Protists Phylum Chrysophyta • Example– diatoms • Found in fresh and marine environment • Diatoms are the most abundant plant-like protist • Make up diatomaceous earth, makes up kitty litter and pool filters • Autotrophic • Many are flagellated and encased in shells or skeletons • Shells are made up of silica

12. Examples of Plant-like Protists Phylum Pyrrophyta • Example – dinoflagellates • Autotrophic • Contains chlorophyll and other green pigments • Major component of oceanic plankton • Large blooms of dinoflagellates cause red tide, which can infect shellfish and poison humans. • These dinoflagellates release a neurotoxin that is harmful to humans.

15. Examples of Animal-like Protists • All heterotrophic • Generally move to find food • Feed on bacteria and other microbes • Holozoic is a term used to describe a microorganisms that obtains their food by engulfing it • Saprozoic organism absorb predigested or soluble nutrients directly through the cell membrane • Can be free living or parasitic • Live in a diverse range of habitats: salt water, fresh water and Most terrestrial habitats • Undergo asexual reproduction by fission • May form a resting cell during unfavorable conditions called a cyst • Range in size – example blood parasites = 2 um vs. Foraminferans = 5 cm

16. Examples of Animals-like Protists Phylum Sarcodina • Generally free-living • May have a motile adult form and develop pseudopods for locomotion • They also use these finger-like projections o obtain food • This phylum can be divided into 4 groups • Amoeba • Formainferians • Radiolarian • Heliozoans.

17. Amoeba • No shell • Demonstrate cytoplasmic movement, this movement is caused by repeated extensions and retractions of the pseudopods • The cytoplasm has two layers: • Ectoplasm • Thin semi rigid layer under the plasma membrane • Endoplasm • The more fluid part that fills the inside of the cell • Continuous movement of the endoplasm causes the amoeba to change shape constantly as it moves

18. Amoeba • Linnaes name the amoeba “chaos chaos” • Engulfing food particles is known as phagocytosis • The food particles are stored within an organelle known as a food vacuole. • A contractile vacuole regulates the amount of water within the amoeba, it has the ability to remove excess water. • As the vacuole expands the water is discharged through a pore in the plasma membrane • Reproduction is asexual through binary fission • Once the amoeba splits in two the organelles grow to their full size although they may split again.

21. Examples of Animal-like Prostists Phylum Ciliphora • Example - paramecium • Characterized by the presence of hair-like structures called cilia • Cilia may cover the entire body • Cilia also function in motility but are shorter and more abundant • Cilia are synchronized for swimming • In sessile organism such as Stenoror Vorticelli the cilia attach the microorganism to a substrate • Most advanced protist

25. Examples of Animal-like Protists Phylum Sporozoa • Example – plasmodium • No independent locomotion • Do not have pseudopods, cilia or flagella • Parasitic • Have spore-like stage during their lifecycle • Sometimes involved two or more hosts • Reproduce sexually in one and asexually in the other • Insects are frequently responsible for transmitting sporozoa from one host to another • Plasmodium causes malaria

28. Examples of Fungus-Like Protists Phylum Gymnomycota • Example– slime molds • Live in cool, shady, most places and are often found under fallen leaves or rotting logs. • Leave a slimy trail as they move • At some stages in their lifecycle slime molds resemble protozoans and become amoeba-like or have flagella, at other times they produce spores similar to fungi