Algae Lecture Notes PDF

Lecture 5 Introduction in Phycology (Algae) Eukaryotes – Algae Euglenophyta Dinoflagellates Chrysophyta – EX. Vaucheria sp Rhodophyta (Red alage) Phaeophyta (Brown algae) Chlorophyta (Green algae) – EX. Chlamydomona + Volvox sp. + Spirogyra sp. Importance of Algae ...

Lecture 5 Introduction in Phycology (Algae) Eukaryotes – Algae Euglenophyta Dinoflagellates Chrysophyta – EX. Vaucheria sp Rhodophyta (Red alage) Phaeophyta (Brown algae) Chlorophyta (Green algae) – EX. Chlamydomona + Volvox sp. + Spirogyra sp. Importance of Algae  Kingdom: Protista or Algae Algae are divided to Prokaryotic (only cyanobacteria) and eukaryotic organisms. Algae are photosynthetic organisms. They carry out probably 50% to 60% of all the photosynthesis on the earth. Most algae are photoautotrophic and carry on photosynthesis (meaning they use sunlight and chlorophyll to make food). Range in size from microscopic single-celled organisms (Microalgae) to large seaweed (Macroalgae). Most of the algae are aquatic. They live in ocean, freshwater, ponds, lakes, streams, hot springs, polar ice, moist soil, trees and rocks environments.  Algae are non-vascular, primitive plants because they lack roots, stems and leaves. They produce spores instead of seeds and have mostly both sexual and asexual reproduction. ## Algae are not plants and can be distinguished from plants by the following : They do not have roots, leaves, and stems, but plants do have. They don’t form true embryos, but plants do have – so that’s why, algae produce spores instead of seeds. Do not have a vascular system. but plants do have  2-Algal Habitat Algae are a group of ubiquitous (present everywhere in distribution ) organisms which are present in diverse habitats such as water (aquatic algae), and land (terrestrial algae). they also grow as an epiphyte, endophytes, and as well as in extreme conditions (ponds, lakes, streams, hot springs, polar ice, moist soil, trees, and rocks environments). 1-Planktonic: ‘free-floating’. 2- Attached: A-Epipelic: On Sediment B-Epiphytic: In Aquatic Vegetation (Macrophytes) C-Epilithic: On rocks. D-Episammic: On sand  3-The algae show a wide range of forms: Some are unicellular. The others are filamentous. The filaments are composed of distinct cells or coenocytes. The coenocytes are multinucleate structure and it lacks cross-walls. Some forms thallus. They are multicellular, highly branched and arranged in leaf like extensions, e.g. sea weeds. A body cannot be differentiated into true roots, stems, leaves and lacks xylem and phloem is called thallus. 4- Algal classification: Algae are being distributed in two kingdoms: 1-Monera: Prokaryotic algae (Cyanophyta ) are placed in the monera 2-Protista: Eukaryotic algae (all other algal divisions) are placed in the Protista The algae are classified on the basis of their pigment composition Kingdom: Monera 1-Division: Cyanophyta (Blue-green algae) class: Cyanophyceae (Myxophyceae) Kingdom: Protista 1- Division: Chlorophyta (Green algae) 4- Division: Pyrrophyta (Dinoflagellates) Class: Chlorophyeae Class: Desmophyceae Class: Charophyceae Class: Dinophyceae 2- Division: Euglenophyta (Euglenoids) 5- Division: Phaeophyta(Brown algae) Class: Euglenophyceae Class: Isogenerate Class: Heterogenerate 3- Division: Chrysophyta (Yellow-green) Class: Cyclosporae Class: Chrysophyceae Class: Xanthophyceae 6- Division: Rhodophyta (Red algae) Class: Bacillariophyceae (Diatomes( Class: Rhodophyceae  4- Algal pigments: All algae contain photosynthetic pigments, Chlorophyll a, b, c, d, e, f (6 types). Carotenoids and Xanthophylls present in yellow, red, and orange pigment. Phycoblins or biliproteins: I. Phycocyanin- blue pigment. II. Phycoerythrin- a pink-red pigment found in Rhodophyceae and Cyanophyceae The algae are classified on the basis of their pigment composition as the following: 1-Euglenophyta Earlier, Euglenoids were classified with plant kingdom (in algae) and animal kingdom (protozoa). Molecular data shows that Euglenoids are closely related with Zooflagellates. They are unicellular, have two flagella and one flagellum is long and the other is short. They are plant like in their pigment. Their pigments are chlorophyll a, b and carotenoids.  However, some photosynthetic Euglenoids lose their chlorophyll when they are grown in darkness. They become heterotrophic and ingest the organic matter. Other species of Euglenoids are always colorless and heterotrophic. Example: Euglena. It has special evolutionary significance. They resemble plants and green algae, as they have similar pigments. They also resemble Zooflagellates (protozoan). It is believed that Euglena is ancestor of both animal and plants. Euglena sp.  2-Dinoflagellates They are most unusual protists as they show different structures. Most dinoflagellates are unicellular, and have two dissimilar flagella Their cells are often covered with shells. This shell is composed of interlocking cellulose plates, some silicates. Their pigments are Chlorophyll a, c, Carotenes, and Fucoxanthin. Ecologically, they are one of the important groups in marine ecosystems, because they produce high ratio of oxygen in marine and freshwater. Dinflagellates show occasional population explosion or bloom. These blooms give an orange, red or brown color to water. They are also known as toxic red tides. Example: Gonyaulax, Ceratium.  3-Chrysophyta (golden algae - Diatoms) They are usually unicellular. They do not have any locomotory organs. Their pigments are Chlorophyll a, c, Carotenes and xanthophyll. The cell wall of each diatom consists of two shells, overlap and fit together. They look like Petri dish. Silica, a glass-like material, is also deposited in the shell. Diatoms are very important in aquatic food chains. Examples: Diatom, Frequilaria, Pinnularia.  4-Phaeophyta (brown algae) All brown algae are multicellular. Their size is from a few centimeters to 75 meters in length. The largest brown algae are called kelps. The kelps are tough and leathery in appearance. They possess leaf-like blades, stem-like stipes, and root-like holdfast. They are non-motile but their reproductive cells have two flagella. Their pigments are Chlorophyll a, c, Carotenes, and Fucoxanthin. Brown algae are common in cooler marine water, especially long coastlines in the intertidal zone. Examples: Fucus, Macrocytosis.  5-Rhodophyta (red algae) They are multicellular. Their body is composed of complex interwoven filaments. These filaments are delicate and feathery. A few red algae forms flattened sheets of cells. They are non-motile. Most of multicellular algae are attached to rocks or other substances by a basal holdfast. Their pigments are chlorophyll a, Carotenes, and Phycoerthrin (red pigment). Some red algae incorporate calcium carbonate in their cell wall from the oceans.  6-Chlorophyta (green algae) They are unicellular, colonial or multicellular. The pigments of green algae are chlorophyll a, b and carotenoids. Most of the green algae have flagella. The cell walls of green algae have cellulose. Green algae have many characters common to plant(similar pigments, reserve products, and cell walls). It indicates that the green algae and plants form a monophyletic lineage. Chlamydomonas (unicellular), Volvox (colonial algae), Spirogyra (filamentous algae) ,Ulva (sheet like multicellular body)  Importance of Algae Some algae like kelps are edible and may be used to overcome shortage of food in the world. Marine algae is also a source of many useful substances like algin, agar, carrageenan, fucoidain and carotenoids. Algae are major products of the aquatic ecosystem. Thus, they play a basic role in food chains. They provide food and oxygen to other organisms.  Chrysophyta Chrysophyta, golden-brown algae or golden algae are a large group of algae, found mostly in freshwater. Class: Xanthophyceae The main characteristics of class: Xanthophyceae They are unicellular motile to simple filamentous forms and are commonly known as yellow-green algae due to the presence of chromatophores which are yellow-green.  Cell wall is rich in pectic compounds, Pigments are chlorophyll a, c, and carotenoids or xanthophyll. The reserve food materials are oil and leucosin and pyrenoids are absent.  Vaucheria sp. The thallus structure of Vaucheria is differentiated into cell wall and protoplasm. The cell wall of the thallus is thin, weak and non-elastic. It is made of two layers, the outer layer is pectic and the inner layer is cellulosic. Vaucheria is a freshwater alga found in ponds, ditches and wet soil.  It is mostly attached to the substratum by colorless rhizoids or holdfasts. It is thallus is a single-branched tubular filament. It contains many minute nuclei present in the living layer of cytoplasm surrounding a large central vacuole. Such a structure is called a coenocyte. Septa appear in connection with reproductive organs. Vaucheria sp. Vaucheria sp. Vaucheria sp.  THE END THANK YOU