Protists Test 3 The protest represent an unusual mix of organisms Protists are more diverse than all other eukaryotes and are no longer considered a single kingdom The organisms found in this group are all eukaryotes and most are single celled for most of their life cycle however some are colonial and there may even be multicellular forms Eukaryotic differences Nucleus with a double membrane Organelles 2 or more chromosomes DNA proteins Since the protists are nutritionally diverse and can be organized into groups based on nutritional methods Autotrophic o Photosynthesis Heterotrophic o Decomposers Heterotrophic o Ingestion hunters and symbiotic Mixotrophic o Combining photosynthesis and ingestive or absorptive methods The evolution of protists is the results of endosymbiosis Primary endosymbiosis resulted in plastid bearing lineages which evolved into red and green algae Secondary endosymbiosis resulted in greater diversification Kingdom Protista is now five subgroups Excavates o Move via flagella o Have feeding groove o Heterotrophic and have modified mitochondria o Groups Diplomonads Both free living and symbiotic species One of the largest subgroups Have two nuclei Multiple flagella Giardia is an infection that comes from drinking untreated water and All known species are symbiotic and some are parasitic Trichomanas Vaginalis is a sexually transmitted males can often be causes diarrhea Parabasalids One of the largest subgroups Anaerobic asymptomatic A diverse clade within the excavate linage Euglenozoans Have distinctive mitochondria Move via flagella Mixed nutritional methods mixotrophic Two Major Subgroups Euglenids o Most are freshwater o Have 1 3 flagella o Primarily photosynthetic but can switch to heterotrophic in the dark o Many lack a rigid cell wall o Have a photoreceptor call an eyespot o Names after Euglena Kinetoplastids o One flagellum o Single large mitochondrion o Both free living and symbiotic species o Some of the symbiotic species are parasitic including Trypanosoma causes sleeping This is a large clade which is thought to have arisen by a secondary endosymbiosis of red sickness Chromalveolates algae Contain two major clades o Stramenopiles Have many different forms some living as multicellular colonies Varied nutritional methods including mixotrophs Three major subgroups Oomycotes Also called water molds Cells walls of cellulose Cells can form aggregated colonies Heterotrophic decomposers Downy Mildew is one common water mold with economic Filamentous bodies importance Diatoms May be freshwater or marine Photosynthetic Have glass like shells known as tests with perforation to allow for exchange of substrates About 5600 described living species estimates 100 000 living species and more than 35000 extinct species based on shell morphology Brown Algae Marine Photosynthetic Deep water to tidal Brown color caused by accessory pigments Cell walls added polysaccharides Cells can form large aggregated multicellular colonies Giant kelp forest Many have gas bladders to keep the plant extending toward the surface Golden Algae May be freshwater or marine all are photosynthetic but some species are mixotrophs Flagellated usually with 2 flagella Usually unicellular but may form colonies o Alveolates Most live as single cells Mixed nutritional methods including parasitic forms Varied forms of motility Dinoflagellates Both marine and freshwater 2 flagella one at the end and on in an equatorial groove Some are photosynthetic many are mixotrophic and many are heterotrophic Many have a cellulose cell wall Members of this group are responsible for red tides which result in massive fish kills along the Gulf Coast Apicoplexans Sporozoans All are heterotrophic and most are parasites which have a mobile stage called a Sporozoite Includes Plasmodium o Causes malaria Toxoplasma o Vectors through cats Ciliates Most species are solitary freshwater Hetertrophic Use cilia short hair like filaments that are made of protein for movement and feeding Cilia may be uniform covering of the organism or can be localized in patches The ciliates are the most complex of the protest with an internal structure that includes an oral groove an anal pore and two types of nuclei The macronucleus handles all the day to day business and the micronucleus functions in sexual reproduction or conjugation Rhizarians o Most live as single cells o Most are heterotrophic but some mixotrophic species are present o Motility based on very thin pseudopodia o May be reclassified as a clade within the chromalveolates o Include Foraminiferans Both marine and freshwater External multi chambered shell known as tests composed of CaCO3 Many species characterized based on shell morphology Radiolarians Pseudopodia extend through pores in the shell Mainly marine Internal skeleton like shell composed of silica glass Many species characterized based on shell morphology Cercozoans ecosystems Very common in marine freshwater and even moist terrestrial Most are heterotrophic but also some are mixotrophic species Mixotrophic species show how unique secondary endosymbiosis Archaeplastids o Are the closest relative of land plants o Often included as part of the land plant supergroup clade o Appears to be among the oldest eukaryotic lineages o Also include Red Algae Mainly marine but some freshwater species Cells can form large aggregated colonies which appears multicellular Mainly shallow water but can occur in clear deep water Red color caused by phycoerythrin Cell wall has added polysaccharides Some species are held upright by CaCO3 Supports the deep water food web Used in cosmetics ice cream paint and sushi Green Algae Includes Chlorophytes and Charophytes Some marine and many freshwater species Some species are flagelleated Unicellular and colony forms Have typical chloroplasts Charophytes are the most probable ancestor of land plants Cell wall has cellulose Unikontes o Very diverse super group that includes protest fungi and animals o Two major clades Large diverse clade Amoebozoans Organisms with lobe shaped pseudopodia Have many different forms some living as multicellular colonies Heterotrophic Move using pseudopodia Four major groups Slime Molds o Have a mobile feeding stage o A stationary reproductive stage with a fruiting body that produces spores Acellular They are also known as plasmodial slime molds This name comes from the plasmodium which is the mobile feeding stage of this organism life cycle In the mobile stage the
View Full Document
Unlocking...