Docsity
Docsity

Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity


Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan


Guidelines and tips
Guidelines and tips

Protists: An Overview of Algae, Protozoa, and Slime & Water Molds, Study notes of Biology

An introduction to the protists, a diverse group of organisms consisting of approximately 160,000 living and extinct species. Mostly single-celled eukaryotes, they inhabit aquatic or moist environments and can be classified into three main types: algae, protozoa, and slime & water molds. In this document, we will discuss examples of each type, including their characteristics, habitats, and classifications.

Typology: Study notes

2021/2022

Uploaded on 09/12/2022

anuprabha
anuprabha 🇺🇸

4.4

(18)

237 documents

1 / 2

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
The Protists
(160,000 living & extinct species; estimates to 200,000 actual species)
mostly single-celled, eukaryotes restricted to aquatic, or moist environments: oceans, ponds, lakes, rivers,
damp soil, tree bark, snow, etc.; some species are colonial or multicellular; autotrophs & heterotrophs;
with or without cell walls; most motile. Genetic analyses have dramatically changed the classification
scheme if this group of organisms. In this course we will discuss examples of three main types of
protists; algae, protozoa and slime & water molds.
Algae [Plant-Like Protists]
(22,000 living species)
diverse group of mostly unicellular protists, some colonial or multicellular; restricted to aquatic or moist
environments: oceans, ponds, lakes, rivers, soil, bark, snow, etc.; photosynthetic with chloroplasts
containing chlorophyll and other pigments, most motile; most with cell wall; cell walls of cellulose,
proteins,, silica or other materials classified according to their kinds of photosynthetic pigments and
composition of cell wall
Fire Algae (Dinoflagellates; Phylum Pyrrhophyta, 2100 species)
unicellular, many symbiotic as zooxanthellae; some produce cell walls of armored plates, blooms
produce toxic red tides, bioluminescent
Diatoms (Glass Algae; Phylum Chrysophyta, 28000 living & extinct species)
most abundant group of algae; unicellular, radial symmetry, cell walls contain silica; common in
freshwater and oceans; source of diatomaceous earth; gliding movement,
Euglenas (Phylum Euglenophyta, 1000 species)
unicellular, only algae without a cell wall; mainly in eutrophic ponds and pools, motile by
flagellum
Green Algae (Phylum Chlorophyta, 9000 species)
aquatic and terrestrial; some form lichens with fungi; diverse body forms, mostly unicellular and
colonial, some filaments or sheets; probably gave rise to plant kingdom; motile by flagella, cell
wall of cellulose; energy stored as starch in vacuole
Red Algae (Red Sea Weeds; Phylum Rhodophyta, 4000 species)
mostly multicellular, body of filaments or sheets attached to substrate by holdfast; some excrete
calcium carbonate=coralline algae; found in warm tropical oceans; thick starchy cell walls yield
commercial quantities of agar and carrageenan
Brown Algae (Brown Sea Weeds; Phylum Phaeophyta, 1500 species)
all multicellular, some up to 60 m long; body differentiated into blade, stipe, floats and holdfast;
found in cooler marine waters especially intertidal areas; used as food especially in SE Asian
countries
pf2

Partial preview of the text

Download Protists: An Overview of Algae, Protozoa, and Slime & Water Molds and more Study notes Biology in PDF only on Docsity!

The Protists

(160,000 living & extinct species; estimates to 200,000 actual species) mostly single-celled, eukaryotes restricted to aquatic, or moist environments: oceans, ponds, lakes, rivers, damp soil, tree bark, snow, etc.; some species are colonial or multicellular; autotrophs & heterotrophs; with or without cell walls; most motile. Genetic analyses have dramatically changed the classification scheme if this group of organisms. In this course we will discuss examples of three main types of protists; algae, protozoa and slime & water molds.

Algae [Plant-Like Protists]

(22,000 living species) diverse group of mostly unicellular protists, some colonial or multicellular; restricted to aquatic or moist environments: oceans, ponds, lakes, rivers, soil, bark, snow, etc.; photosynthetic with chloroplasts containing chlorophyll and other pigments, most motile; most with cell wall; cell walls of cellulose, proteins,, silica or other materials classified according to their kinds of photosynthetic pigments and composition of cell wall Fire Algae (Dinoflagellates; Phylum Pyrrhophyta, 2100 species) unicellular, many symbiotic as zooxanthellae; some produce cell walls of armored plates, blooms produce toxic red tides, bioluminescent Diatoms (Glass Algae; Phylum Chrysophyta, 28000 living & extinct species) most abundant group of algae; unicellular, radial symmetry, cell walls contain silica; common in freshwater and oceans; source of diatomaceous earth; gliding movement, Euglenas (Phylum Euglenophyta, 1000 species) unicellular, only algae without a cell wall; mainly in eutrophic ponds and pools, motile by flagellum Green Algae (Phylum Chlorophyta, 9000 species) aquatic and terrestrial; some form lichens with fungi; diverse body forms, mostly unicellular and colonial, some filaments or sheets; probably gave rise to plant kingdom; motile by flagella, cell wall of cellulose; energy stored as starch in vacuole Red Algae (Red Sea Weeds; Phylum Rhodophyta, 4000 species) mostly multicellular, body of filaments or sheets attached to substrate by holdfast; some excrete calcium carbonate=coralline algae; found in warm tropical oceans; thick starchy cell walls yield commercial quantities of agar and carrageenan Brown Algae (Brown Sea Weeds; Phylum Phaeophyta, 1500 species) all multicellular, some up to 60 m long; body differentiated into blade, stipe, floats and holdfast; found in cooler marine waters especially intertidal areas; used as food especially in SE Asian countries

Protozoa [Animal-Like Protists] (>50,000 living & extinct species)

mostly single celled or colonial, heterotrophs, nonphotosynthetic, no chloroplasts; lack cell wall, heterotrophic nutrition, most are motile; classified according to type of motility Amoebas (Phylum Sarcomastigophora) 44,000 living & extinct species simplest of protozoan protists; ‘amoeba’ means to change form - move by means of false feet (pseudopodia) some species produce shells of silica (radiolaria) or calcium carbonate (foraminiferans) Flagellates (Phylum Sarcomastigophora) 1,500 species most are symbiotic with other organisms, a few are pathogens; move by one or more flagella Ciliates (Phylum Ciliophora) 8,000 species the largest, most diverse group of protozoans; ;most are freeliving, motile by cilia; great diversity of size, shape and internal organelles Apicomplexans (Phylum Apicomplexa) 5,000 species all are nonmotile parasites with complex life cycles that alternate between sexual and asexual reproduction

Slime & Water Molds [Fungus-Like Protists] (11,500 living species)

Superficially resemble fungi; nonphotosynthetic heterotrophs with body of hyphal filaments; produce flagellate reproductive cells; some have cell wall of cellulose, others of chitin. Plasmodial Slime Molds (Phylum Myxomycota) (500 sp) feeding stage is motile, plasmodial stage; fruiting body a sporangium producing swarm cells and myxamoeba Cellular Slime Molds (Phylum Acrasiomycota) (65 sp) feeding stage is unicellular amoeboid like cells; fruiting body is multicellular pseudoplasmodium (=slug) producing spores. Water Molds (Phylum Oomycota & Chytridiomycota) (170 sp) aquatic multicellular heterotrophs; mycelium of threadlike hyphae; most are saprobes others are parasites of plants, animals and other fungi; mostly aquatic, a few are terrestrial