Protists chapter 28By: Pablo J Fonseca *(with help and information from Google search engine and Campbell Reece AP biology textbook)

INTRODUCTION TO PROTIST What is a Protist? A Protist is virtually any eukaryote that is neither a plant, animal, or fungi. Throughout this PowerPoint I will introduce you with some of the most significant groups of protists. You will learn about their structural and biochemical adaptations as well as their enormous impact on ecosystems, human health, industry, and the world.

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

Concept28.1 protists are an extremely diverse assortment of

eukaryotes• Protists exhibit more structural and functional diversity

than any other group of organisms.• Most protists are unicellular ( meaning composed of only 1

cell), although there are some colonial and multicellular species( meaning having multiple cells).

• Even though most protists are unicellular and are only composed of one cell this doesn’t mean that they are very simple in fact in some cases it can be considered quite the opposite. This should be expected of a cell though that has to carry out all the functions that a multicellular organism does.

• As well must Protist at the cellular level become exceedingly complex.

• Protist are the most nutritionally diverse of all eukaryotes.• There are also many different ways Protist acquire they're

nutriention.• some Protist are photoautotrophs containing chloroplasts.

Some are Heterotrophs absorbing organic molecules or ingesting large food particles.

• Yet the most remarkable of the Protist to obtain they're nutrition are the Mixotrophs(Mixotrophs combine photosynthesis and heterotrophic nutrition.)

A photo of some Mixotrophs

28.1 cont.…..• In such an ecological context, we can divide protists into three

categories: photosynthetic protists mean plant like, or algae; ingestive( animal like) protists, or protozoans; and absorptive (fungus like protists)

• The places Protist inhabit are diverse as well as it ranges from rocks to water.

• Overall though it has been proven scientifically that Protist prefer aquatic environments. They are found almost anywhere there is water, including moist terrestrial habitats such as damp soil and leaf litter. In ocean, ponds, and lakes, many protists are bottom dwellers that attach themselves to rocks and other substrates or creep through the sand and silt.

• Reproduction and life cycles highly varies throughout different protists.

• Some Protist are asexual and others can reproduce sexually or at least employ the sexual processes of meiosis and syngamy. All three basic types of sexual life cycles are represented among protists, along with some variations that do not quite fit any of these types.

Endosymbiosis in eukaryotic evolution

28.2 diplomads and Parabasalids have modified

mitochondriaNow that we have examined some of the broad patterns in eukaryotic evolution, we will look more closely at several of the main clades of Protist.

28.2 cont.….We begin with diplomonadida and Parabasalids. Protist in these 2 clades lack plastids, and they’re mitochondria do not posses DNA, electron transport chains, or enzymes that are normally needed for the citric acid cycle.- Diplomads have two equal sized nuclei and multiple

flagella. - Parabasalids include the Protist called trichomonad. The

most well-known species is trichomonad vaginalis, a common inhabitant of the vagina of human females

28.3 eugenozoans have flagella with a unique internal structure

• Eugenozoans is a diverse clade that includes predatory heterotrophs, photosynthetic autotrophs, and pathogenic parasites. The main features that differentiate the protists in the clade are their flagella.

• Kinetoplastids have a single, large mitochondrion that contains an organized mass of DNA called a kinetoplast.

• Euglenids have a pocket at one end of the cell from which one or two flagella emerge.

28.4 alveolates have sacs beneath the plasma

membraneAnother clade of protists whose identity is emerging from molecular systematics, Alvolata , is characterized by membrane bound sacs just under the plasma membrane. The function of the alveoli is unknown; researches hypothesize that they may help stabilize the cell surface or regulate the cell’s water and ion content.- Dinoflagellates are abundant components of both marine and

freshwater phytoplankton. There are also heterotrophic Dinoflagellates. Of the several thousand known Dinoflagellates most are unicellular, but some are colonial. Each has a characteristic shape that in many species is reinforced by internal plates of cellulose. Two flagella located in perpendicular grooves in this “armor” make Dinoflagellates spin as they move through water.

- Apicomplexans are parasites of animals, and some cause serious human diseases. The parasites spread though their host as tiny infectious cells called Sporozoties.

- Ciliates are a large, varied group of protists named for their use of cilia to move and feed.

- Conjugation In prokaryotes, the direct transfer of DNA between two cells that are temporally joined. In ciliates, a sexual process in which two cells exchange haploid micro nuclei.

28.5 cont.…Diatoms are unicellular algae that have a unique glass-like wall made of hydrated silica embedded in an organic matrix. Algae-golden algae, or cryophytes, are named for their color, which results from their yellow and brown carotenoids.- Brown algae the largest and most complex type of algae

are brown algae, or phaeophyte. All are multicellular, and most are marine. Brown algae are especially common among temperate coasts, where the water is cool. Brown algae is very often your common seaweed.

- Now while seaweed may seem simple to theEye that is very deceiving because some Seaweeds are actually quite complex.Seaweed is composed of holdfast, blades,And stipes. Please open your book to pg.560For more info.

28.5 stramenopiles have “ hairy” and smooth flagella The clade stramenopiles includes several groups of heterotrophs as

well as certain groups of algae. The name of the clade refers to a flagellum with numerous fine, hair like projections, a characteristic of these protists. In most stramenopiles, this “hairy” flagellum is paired with a smooth(non-hairy) flagellum. In some stramenopiles groups, the only flagellated cells are motile reproductive cells.- Oomycetes include water molds, white rusts, and downy mildews. Early morphological studies show that these organisms show that they organisms are fungi.

28.5 cont.Alternation of generations- A life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte; characteristic of plants and some algae.• Heteromorphic meaning that the sporophytes and

gametophytes are structurally different.• Isomorphic generations in which the sporophytes and

gametophytes look similar to each other, although they differ in chromosome number.

28.6 cercozoans and radiolarians have

threadlike pseudopodiaA relatively young new clade, Cercozoans, contains a diversity of

species that are among the organisms referred to as amoebas. Amoebas were formally defined as protists that move and feed by means of pseudopodia, extensions that may bulge from virtually any where on the cell surface.• Foraminiferans, or forams, are named for their porous shells, called

tests. Foram tests are generally multichambered and consist of organic material hardened with calcium carbonate.

• Radiolarians are mostly marine protists whose test are fused into one delicate piece.

28.7 amoebozoans have lobe-shaped pseudopodia

28.7 cont.…

28.8 Red algae and green algae are the closest relatives of land plants• Red algae have colors ranging from green to

black, owning varying amount of the accessory pigment phycoerythrin. Most red algae are multicellular.