Protists Historically a catch all category Are neither

Protists • Historically a ‘catch all’ category • Are neither animals, plants, fungi, nor prokaryotes. • Are the first eukaryotic organisms to evolve from prokaryotes. They gave rise to all other eukaryotic lifeforms (plants, animals, fungi, modern protists). • All protists are eukaryotic, the only unifying feature of the group.

A eukaryotic cell

Figure 28. 2 A model of the origin of eukaryotes Membrane infolding Endosymbiotic theory

Some general protist features • Eukaryotic • Most are aerobic (cellular respiration occurs in mitochondria) • Most are motile (e. g, flagella/cilia) • Most are unicellular (some may be colonial or multicellular) • Most live in aquatic habitats (wherever there is moisture) • Reproduction occurs both asexually and sexually: asexually: budding, fission, multiple fission *sexually: production of diploid cells via meiosis

Kingdom Protista • All protists are eukaryotes. This means that their cells contain a nucleus, a membrane-bounded structure that encloses the cell's genetic material. • Some protists are autotrophs like plants, others are consumers like animals. Unlike plants and animals, however, protists do not have cells organized into specialized tissues.

Protozoans Unicelluar Algae Multicellular algae Slime molds Protist Kingdom Brum et al, 1994

Protista Classified by Nutrition • The first detailed descriptions of protists were made in 1676 by the inventor of the microscope, Dutch naturalist Leewenhoek. • The term Protista was first used in 1862 by the German biologist Haeckel to describe microscopic organisms that were neither animallike nor plantlike • The classification is currently based on the structure and organization of the cell, the presence of organelles, and the pattern of reproduction or life cycles. The fivekingdom system divides the Protista into 27 phyla. However, classifications based on comparisons of cell physiology and DNA sequences suggest that many protist phyla may be sufficiently large and diverse to be classified as kingdoms.

• Autotrophic Protists are called “Algae”. Scientists believe they gave rise to the kingdom Plantae • Ingestive Heterotrophic protists are called “Protozoa”. Scientists believe they gave rise to the kingdom Animalia • Absorptive heterotrophic protists are called “Slimemolds”. Scientists believe they gave rise to the kingdom Fungi

Protozoa classified by locomotion • The word protozoa means "little animal. " They are so named because many species behave like tiny animals—specifically, they hunt and gather other microbes as food. • Protozoa mainly feed on bacteria, but they also eat other protozoa, bits of stuff that has come off of other living things —what's generally called organic matter—and sometimes fungi. • Sarcodines, Flagellates, Ciliates, Sporozoans, • Food Vacuoles Actinophrys feeding on Colpidium

1. Amoebas Pseudopodia

Phylum Sarcodinia • Engulf prey with pseudopodia • Some naked and ameboid (Ameba proteus) • Foraminiferans, warm oceans secrete calcium carbonate shells w/ holes for pseudopodia • Form chalk/limestone such as White Cliffs of Dover • heliozoans “sun animals” in fresh water • free or attached by a stalk, some naked some silica skeletons • radiolarians secrete elaborate silica shells

2) Flagellates a. Giardia Purves et al. , 2001

Phylum Zoomastigina (zooflagettes) • Heterotrophic flagelleates • Both free living and parasitic • Trypanosoma sleeping sickness and Chaga’s disease • Giardia lakes and reservoirs causes diarrhea, cramps, fatigue, loss of weight

b. Trypanosoma, causes African sleeping sickness Parasitic protists infect more than half the world’s population!!

Phylum Euglenophyta • Freshwater, especially polluted habitats • 2 flagella, one for locomotion one to detect light • lack cell walls but have a transparent pellicle made of pp • chlorophyll a & b & carotenoids • can be autotrophic or heterotrophic

b. Euglena

Apicomplexans • Spore forming parasites of animals (including humans). • Have complex life cycles. • Plasmodium the cause of malaria transferred from mosquito to human to mosquito.

4. Ciliates

II. Slime Molds • Heterotrophs • Not closely related to fungi, appear similar due to convergent evolution. • Probably evolved from an ameoboid ancestor. • Two types: – 1. Cellular – 2. Plasmodial

1. Cellular Slime Molds

2. Plasmodial Slime Molds Plasmodia have syncytial structure. One huge cell with many nuclei Shirley Owens, Center for Electron Optics, Michigan State University Brum et al, 1994 Sporangia - stalked fruiting bodies

Slimemolds, Watermolds & Mildews • Slime molds have traits like both fungi and animals. They have very complex life cycles involving multiple forms and stages. During good times, they live as independent, amoeba-like cells, dining on fungi and bacteria. But if conditions become uncomfortable—not enough food available, the temperature isn't right, etc. —individual cells begin gathering together to form a single structure. • Water mold caused the Irish Potato Famine in 1846

Plasmodium Slime. Molds • Form plasmodium: a mass of cytoplasm that contains many diploid nuclei but no cell walls or membranes – its feeding stage • Creeps by amoeboid movement – 2. 5 cm/hour • May reach more than a meter in diameter • Form reproductive structures when surroundings dry up • Spores are dispersed by the wind and grow into new plasmodium • Tokyo’s Railway System

Cellular Slime Molds • In feeding mode, they exist as individual amoebic cells • When food becomes scarce, they come together with thousands of their own kind to reproduce • May look like a plasmodium

Water Molds and Downy Mildews • Live in water or moist places • Feed on dead organisms or parasitize plants • Fuzzy white growths

Harmful Protists • cause mold and mildew which can spoil food and cause allergic reactions

III. Unicelluar Algae • Most are photosynthetic, have chlorophyll. • Most are unicellular but can be colonial. • Abundant in marine and freshwater plankton, the bottom of the food chain. • Family Tree of Chloroplasts

Classification of Algae • When you think of algae, you probably think of seaweed or the green, slimy stuff that forms on the walls of untreated, dirty swimming pools. • Algae are found in bodies of fresh and salt water across the globe. They can also grow on rocks and trees and in soil when enough moisture is available. (They also grow on the hair of the South American sloth, giving the animal a greenish color. ) • Most algae are able to make energy from sunlight, like plants do. They produce a large amount of the oxygen we breathe. However, at some stages of their lives, some algae get their nutrients from other living things.

Figure 28. 6 b Dinoflagellates: Pfeisteria piscicida 1. Dinoflagellates

Phylum: Pyrrophyta/dinoflagellata • 2 flagella, one wrapped around middle in groove and one projecting • mostly photosynthetic, chlorophyll a and carotenoids, some heterotrophic • store food in starch • abundant in warm oceans • formed large oil deposits • reproduce asexually through binary fission • “red tide” which accumulates in shell fish and produces a nerve poison

Harmful algal bloom of the toxic dinoflagellate Noctiluca, off California

Phylum Chrysophyta (diatoms and golden algae) • Marine/wet spots (rocks, plants, wood) • Chlorophyll a & c & fucoxanthin (gives a yellow-brown color) • Store excess food as oil, important in formation of petroleum deposits • Diatoms have a rigid cell wall with pectin and silica glass (Si. O 2) • Symmetrical • Ancient deposits for diatomaceous earth • mined for abrasives in silver polish and toothpaste, packing in air and water filters

Phylum Phaeophyta (brown algae) • 1500 species • fucoxanthin • store carbohydrates as laminarin and mannitol • flagellated sperm • marine, especially cold coastal water • kelp can be 30 m (100 ft) tall • holdfast root, stipes stems, blades leaves, bladders afloat, thallus entire structure

Phylum Rhodophyta (red algae) • • • 4000 species of seaweed pigment phycoerythrin from phycobilins (like cyanobacteria) store food in a starch like compound called floridan produce polysaccharide agar-agar: used to thicken soups and prepared media for bacterial growth harvested for carrageenan, thickening agent in ice cream Nori, Japanese seaweed Shows alternation of generations can be black or green absorb blue light

Phylum Chlorophyta (Green Algae) • 7000 named species, mostly freshwater a few marine • unicellular and muticellular • chlorophyll a & b, store food as starch • Volvox simple colonial suggests arisal of multicellularity 1: Ulva 2: Chlorella 3: Pediastrum 4: Codium 5: Pterosperma 6: Chlamydomonas

Daughter cells remain attached to the parent cells COLONY Colonial Green Algae, Volvox

Evolution of multicellularity! A colonial protist multicellular organism when some members of the colony took on different functions. As cells specialized, they lost some of their previous functions and so became dependant on the colony.

IV. Multicellular Algae: Seaweed 1. Red 3. Green 2. Brown

What distinguishes plants from algae? 1. Roots 2. Stems 3. Leaves

Figure 28. 19 x Kelp forest: Channel Islands

Multicellular green algae probably gave rise to plants. • Have the same type of chlorophyll as plants. • Some biologists think that multicellular green algae should be considered plants. • Have alternation of generations.

You use algae everyday • algae and their by products are ingredients used in… – Toothpaste – Ice cream – Puddings – Agar – Etc. . .

Beneficial Protists • Used as insect pathogens • used in ice cream, soups, nori (seaweed in sushi), jello, agar, vitamin supplements • ancient dinoflagellates formed oil deposits • bioluminescent • diatoms mined for fine abrasives in silver polish and toothpaste and as packing in air and water filters • marine phytoplankton make up ~70% of the oxygen on the planet

Protista Links • • • Protist Kingdom: Phylogenetic Tree: Protozoa Bio 4 Kids: Microbe Zoo, Dirtland: Campbell's Chapter 28: Protist