protista.pptx

these slides contain general information about protista characteristics and classification

1. Kingdom Protista This content is only for education purpose Dr. Poonam Bansal Assistant Professor Maharishi Markandeshwar (Deemed to Be University) Mullana

2. The classification of five kingdoms was given by Robert Whittaker in 1969, and the Protista kingdom was a part of those five kingdoms. The term ‘Protista’ is derived from the Greek word “ protistos ”, meaning “the very first”. Simple eukaryotic organisms that are neither plants nor animals or fungi. They are unicellular in nature but can also be found as a colony of cells. Mostly live in water, damp terrestrial environments, or even as parasites. Cell of these organisms contain a nucleus which is bound to the organelles. Some of them even possess structures that aid locomotion like flagella or cilia. Protista

3. Salient Features T he kingdom of Protista is a diversified one, it is difficult to coherently characterize them in a simplified manner. The organisms that form a part of this kingdom are diverse and multifarious in terms of bodily structure, reproductive abilities, and nutrition. T he characteristics of Protista are as fellow: Some may be unicellular, others may be colonial or multicellular. P rotists are a part of eukaryotic kingdoms, their organizational structure can be varied. They have multiple organelles that include a nucleus, mitochondria, plastids, food vacuoles and flagella. T hey are capable of both sexual and asexual reproduction. Protists are free-living organisms, but they are also capable of living interdependently with another organism.

4. Symbiosis is observed in the members of this class. The relationship between a protist and another organism is either a collaborative one or a parasitic one. In a collaborative relationship, both of them benefit from each other, whereas in a parasitic relationship, the protist is deriving the benefit by feeding off the host. For example kelp (seaweed) is a multicellular protist that provides otters, protection from predators amidst its thick kelp. In turn, the otters eat sea urchins that tend to feed on kelp Usually, there are two different sides to protists - one side is beneficial to humans, while the other side harms them in the form of dangerous, life-threatening diseases. Protists have the dual characteristics of both mobility and immobility. While some protists are ambulatory as they use cilia, flagella, and pseudopodia as fake feet to commute, while others are stationary as well. They can be both autotrophic ( preparing their own food) and heterotrophic (acquiring outside sources of nutrition). For example, Euglena performs mixotrophic nutrition as both holotropic (where the organism captures and ingests the food) and saprotrophic (where the organism releases enzymes that convert organic matter into simpler products) modes of nutrition can be observed in them. 

5. Classification of Protista The classification of protists is done on the basis of their nutritional habits, mobility and modes of reproduction. They can be broadly classified into three categories:  Protozoan protists Photosynthetic protists or Protist algae Slime moulds

6. Photosynthetic Protists or Protist Algae Photosynthetic protists are eukaryotic organism that mainly contains chloroplast and prepare their own food.  These are unicellular and possess flagella for movement.  Most have mitochondria. They can be parasites. They all prefer aquatic or moist environments. T hey also contain  chlorophyll , a pigment which absorbs light energy for photosynthesis. Photosynthetic protists are considered plant-like protists. Protists that are capable of photosynthesis include various types of algae, chrysophytes , dinoflagellates and euglena . Reproduction is entirely asexual.

7. Dinoflagellates one-celled aquatic organisms and having characteristics of both plants and animals. Nutrition among dinoflagellates is autotrophic, heterotrophic or mixed; some species are parasitic or commensal. Dinoflagellates range in size from about 5 to 2,000 micrometres (0.0002 to 0.08 inch). Dinoflagellates possess two flagella, one (the transverse flagellum) may be contained in a groove-like structure around the equator of the organism (the cingulum), providing forward motion and spin to the dinoflagellate, the other (the longitudinal flagellum) trailing behind providing little propulsive force, mainly acting as a rudder. Some of the examples of dinoflagellates are Glenodinium , Peridinium , Gymnodinium , Ceratium etc. Symbiodinium  sp. ( Dinophyceae ): Dinoflagellates

8. Chrysophytes Chrysophytes ( Chrysophyceae , Heterokontophyta ) are mainly unicellular or colonial golden-brown algae, which may be flagellate, but there are also some multicellular species They are sometimes referred to as golden-brown algae due to their coloration from specific photosynthetic pigments. They are not considered truly autotrophic by some biologists because nearly all chrysophytes become  facultatively heterotrophic  in the absence of adequate light, or in the presence of plentiful dissolved food. Contain chlorophyll, xenthophyll . Rigid cell wall made of pectin/silica/cellulose. I nclude diatoms and desmids . Some of the examples are Navicula , Cymbella , etc. Golden brown algae

9. Euglenoids are either unicellular or colonial. A bout 2/3 of these are heterotrophic and have colorless plastid. A re able to photosynthesize, and have green plastids with chlorophyll  a  and  b  and carotenoid pigments. The cytoplasm of  Euglena  and other euglenoids contains many paramylon starch storage granules. E uglenoid cells are covered by a pellicle composed of ribbonlike, woven strips of proteinaceous material that cover the cell in a helical arrangement from apex to posterior. Some examples are Euglena, Phocus , etc. Euglenoids Euglena

10. Slime moulds   have  cellulose in the cell walls  of their spores. S lime molds are  heterotrophs. slime molds do not have chitin in their cell walls and have a  diplontic life cycle . These organisms move about as amoebae engulfing bacteria (unlike fungi, who digest food externally). When conditions become unfavorable, whether due to lack of food or lack of moisture, they form spores. They can be found in damp substrates with ample bacteria and are most frequently found on decaying logs and forest duff. They resemble fungal organisms and come in dazzling colours of multiple variants. Moreover, they are likely to inhabit places that are murky and damp. Derive their nutrients from decaying and decomposing organic material. Some examples of slime moulds are Fuligo , Dictydium , etc. Dazzling slime mould

11. Protozoan Protists The origin of the word 'protozoa' lies in the Latin word for first animals. Protozoans range in diameter from a few thousandths of a millimetre to several millimetres . Protozoan usually single-celled and heterotrophic. They are also strictly non-multicellular and exist as either solitary cells or cell colonies. Protozoa come under the group of parasitic protists that feed on other organisms that are mostly dead, for nutrients. They are eukaryotes and therefore possess a “true,” or membrane-bound, nucleus. Protozoan Protists

12. They are also non-filamentous . M any protozoans either perform photosynthesis themselves or benefit from the photosynthetic capabilities of other organisms . They are motile; nearly all possess flagella, cilia or pseudopodia that allow them to navigate their aqueous habitats Protozoa can be further classified on the basis of their motility. The classification of protozoan protists is given below: Flagellated protozoans Ciliated protozoans Amoeboid protozoans Sporozoans

13. Flagellated protozoans The flagellated protozoans range from a simple oval cell with one or more flagella to the structural sophistication of the collared flagellates. Many other flagellated protozoans can develop stalks that connect them to a substrate, either as single cells (e.g., the genus  Paraphysomonas ) or as colonies (e.g., the genus  Codosiga ).  They are free living, aquatics, parasites, commensals. R eproduction is by binary fission. For example: Trypanosoma, Giardia, Leishmania, Trichomonas Giardia genus

14. Ciliated protozoans Cilia are used for locomotion and driving food. Body is covered by pellicle. Nutrition is holozoic except in the parasitic form. They are homogeneous group, although even they have evolved considerable variation on the cilia-covered cell. In hypotrich  Euplotes, cilia are combined to form thick conical structures, called cirri, which the ciliate uses to crawl along surfaces. For example: Paramecium, Vorticella, Opalina , Balantidium Paramecium

15. Amoeboid protozoans Pseudopodia used for engulfing food particles and locomotion. The body may be covered with plasmalemma or a shell. Asexual reproduction takes place by binary fission, multiple fission, budding and spores. Sexual reproduction occurs through syngamy. The naked amoebae are the simplest of the amoebae. They have no defined shape and extend one or many pseudopodia. For example: Amoeba, Pelomyxa, Entamoeba. Amoeba

16. Sporozoans All sporozoans are endoparasites. Locomotory organs are absent. Nutrition is parasitic. Life cycle has two distinct sexual and asexual phases. For example: Plasmodium, Monocystis , Eimeria Plasmodium