Phycology - The Study of Algae PDF

# Phycology - The Study of Algae ## Introduction - Phycology is the study of algae. - Algae are chlorophyll-bearing organisms having a thallus, which is the plant body. - Algae can be microscopic (**Micro Algae**) or macroscopic (**Macro Algae**). ## Ecology of Algae - **Aquatic Algae:** - **F...

# Phycology - The Study of Algae ## Introduction - Phycology is the study of algae. - Algae are chlorophyll-bearing organisms having a thallus, which is the plant body. - Algae can be microscopic (**Micro Algae**) or macroscopic (**Macro Algae**). ## Ecology of Algae - **Aquatic Algae:** - **Freshwater Algae** - **Marine Water Algae** - Most algae live in marine water (**Cuicho Algae**) - **Terrestrial Algae:** Found on moist soil and in hot springs. - **Thermophytes:** Can tolerate high temperatures. - **Cryptophytes:** can tolerate low temperatures. - **Aero Phytes:** grow in snow and ice. ## Classification of Algae - **Benthic Algae:** Living attached to the bottom of sediments - **Key of classification:** | Type | Nucleus | Cell Wall | Pigment | Plastids | Pyrenoid | Food Storage | Flagella | Sexual Reproduction | |---------------|----------|-------------------------------------|-------------------------------------------|-----------------|------------------------------------|---------------|----------|----------------------| | **Cyanophyta** | Prokaryote | Hemi Cellulose, mucopeptide | Chl (a), Phycocyanin | No Plastids | Absent | Cyanophg-Cean+Starch | Absent | Absent | | **Chlorophyta** | Eukaryotic | Cellulose | Chl (a) + (b), Chlorophyll | Chloro Phyta | Starch + Sheath | Thue Starch | Present | Present | | **Bacillariophyta** | Eukaryotic | Silicified | Chl (c), Diato Xanthine (Yellow) | Chromophyta | Naked Pyrenoid | Leu Cosin | Present | Present | | **Phacophyta** | Eukaryotic | Cellulose, Fucocin | Chl (a), Fu Coxanthin | Chromophyta | Naked Pyrenoid | Laminin | Present | Present | **Main Types of Algae**: 1. **Cyanophyta (Cyanobacteria)**: Also known as blue-green algae. 2. **Chlorophyta:** Green algae. 3. **Bacillariophyta:** Diatoms (brown algae). 4. **Phaeo Phyta:** Brown algae. 5. **Rhodophyta :** Red algae ## Nutrition in Algae - Algae have two sources of nutrition: - **Source of Energy:** Light (photosynthesis) or oxidized organic compounds (chemosynthesis). - **Source of Carbon:** Carbon Dioxide (CO2) or organic compounds. - **Types of nutrition:** - **Autotrophic:** - **Phototrophic:** Algae get energy from light and carbon from CO2. - **Chemoautotrophic:** Algae get energy from oxidized organic compounds and carbon from CO2. - **Heterotrophic:** - **Photoheterotrophic:** Algae get energy from light and carbon from organic compounds. - **Chemoheterotrophic:** Algae get energy from oxidized organic compounds and carbon from organic compounds. - **Mixotrophic:** This is a combination of both autotrophic and heterotrophic nutrition. ## Thallus Organization in Algae - Algae lack roots, stems, and leaves. - Algae are classified by the organization of their thallus: 1. **Unicellular form:** Single cells (e.g., **Gloeocapsa Chrooococcus**) 2. **Colonial form:** Groups of cells: - **Regular colonies:** (e.g., **Merismopaedia** - flat colony) - **Irregular colonies:** (e.g., **Microcystis**) 3. **Filamentous form:** Chains of cells (e.g., **Oscillatoria, Nostoc, Spirulina**) - **Filament:** A row of adjacent cells surrounded by a gelatinous membrane in blue-green algae (e.g., **Nostoc, Spirulina, Trichome**). - **Inchioro Phyta:** A unicellular thallus surrounded by a gelatinous membrane. - **Non-motile:** No flagella, movement is limited to passive drifting in water (e.g., **Chlorella, Pediastrum, Hydrodictyo**). - **Motile:** Flagella present (e.g., **Chlamydomonas, Gonium, Pandorina, Eudorina, Volvox**). - **Coenobium:** A colony where the number of cells remains constant throughout development. ## Multi-cellular filamentous Thallus - **Simple filament:** A single row of cells (e.g., **Spirogyra**) - **Spiral Shape:** Chloroplasts are shaped spirally. - **Vlothrix:** This type of alga has a **girdle shape** and the chloroplast is present only in **vegetative cells**. - **Holdfast:** A structure that helps the alga attach to a substrate for support. - **Oedogonium:** - **Vegetative Cells:** These cells have a **reticulate shape**. - **Oogonium**: This is the female reproductive organ. - **Anthredium:** This is the male reproductive organ. - **Branched Filament:** Lateral outgrowth of a filament. - **True Branch:** A branch that grows from a node, forming a complete new filament (e.g., **Cladophora**). - **Massive Parenchyma Thallus:** Multiple layers of closely packed cells forming a solid structure. - **Hetero tnchows Thallus:** Heterocyst is present in the thallus. ## Salia Ceous Thallus - **Viva Coliva:** A macroscopic alga with a **frond** and a **stipe**. The frond resembles a leaf structure and the stipe is a stem-like structure. - **Siphonaceous (coenocytic) Thallus:** A single cell with multiple nuclei (e.g., **Codium**). - **Tubular:** Can be hollow and divided into sections. - **Multinuclreated:** The cell contains multiple nuclei. ## Stigeo clonium - **Heteromorphic thallus:** The plant body is differentiated into two parts: - **Erect system:** the aerial part of the alga. - **Prostrate system:** the lower part of the alga attached to the surface. ## Motility in Algae - **Monoid:** Algae that have locomotive organelles, usually **flagella**. - **Coccoid:** These types of algae lack locomotion organs. - **Types of Movement:** 1. **Oscillation:** A pendulum like movement (e.g., **Anabaene**). 2. **Gliding:** This is a type of movement seen when the gelatinous membrane of the organism comes in contact with solid substrate. 3. **Swimming:** Movement by using flagella (e.g., **Chlorophyta**). - **Chemotaxis:** Movement towards a chemical stimulus such as a nutrient. - **Phototaxis:** Movement towards or away from light. 4. **Jerky Movement:** Fast movements of the body. ## Flagella - **Functions:** Flagella are cytoplasmic elongations that help with movement, particularly in water. - **Structure:** - **Central Fibril:** The central microtubule in the flagella. - **Peripheral Fibril:** The peripheral microtubule in the flagella. - **Plasma membrane:** Surrounds the entire flagellum. - **Granule (blepharoplast):** A small, granular structure at the base of the flagellum. - **Eukaryotic flagellum:** Has a 9+2 structure: - **Double microtubules:** 9 microtubules surround 2 central microtubules. - **Peripheral:** 9 microtubules are thicker. - **Prokaryotic flagellum:** Does not have a 9+2 structure. ## Flagellar Classification - **Number of Flagella:** - **Uniflagellated:** Single flagellum. - **Biflagellated:** Two flagella (e.g., **Chlamydomonas, Ulothrix**). - **Quadriflagellated:** Four flagella. - **Multiflagellated:** Multiple flagella (e.g., **Autogonoum**). - **Type of Flagella:** - **Whiplash (Acronematic):** Thread-like with a smooth surface. - **Tinsel (Pleuronematic):** Pinna-like with hair-like projections. - **Position of Insertion:** - **Terminal:** Flagella anchored at the very end of the organism. - **Subterminal:** Flagella is anchored near the end but not at the very end. - **All over the surface:** Flagella are evenly distributed over the surface of the organism. - **Length and Type:** - **Isokont Flagella:** Flagella of the same type and length. - **Heterokont Flagella:** Flagella of the same type but different lengths. - **Zoospore:** A motile spore used for reproduction in some algae. ## Reproduction in Algae - **Types of Reproduction:** - **Vegetative Reproduction:** Occurs in primitive algae and is based on the parental body splitting up into two or more parts. - **Asexual Reproduction:** Occurs in more advanced algae and involves the production of spores. - **Sexual Reproduction:** Occurs in the most advanced algae and involves fusion of gametes to form a zygote. - **Vegetative Reproduction** - **Binary Fission:** The parent cell divides into two daughter cells (e.g., **Cyanophyta, coccoid algae (Gloeocapsa)**). - **Hormogonia:** Short free filaments that fragment from a filament (e.g., **Nostoc**). - **Fragmentation:** The filament breaks into several parts, each of which can develop into new individuals (e.g., **Filamentous and non-filamentous algae, Microcystis**). - **Uniparent Reproduction:** New organisms are formed through spores or fusion of gametes. - **Spores:** Produced by single-parent algae. - **Fusion:** The joining of two gametes to form a zygote. - **Germination:** The development of a new organism from a spore. - **Asexual Reproduction** (by formation of autospores or aplanospores) - **Autospore:** a type of aplanospore formed inside the parent cell through cell division. - **Aplanospore:** a non-motile spore that lacks flagella. - **Hypo Spores:** Thick walled spores found in **Chlamydomonas** and in some **colonial forms**, for example **Pediastrum** and **Hydrodictyon**. - **Endospores:** Spores formed inside the cell, releasing after the cell wall ruptures or through a pore (e.g., **Bacillariophyta (diatoms)**). - **Exospores:** Spores formed on the outside of the cell wall (e.g., **Bacillariophyta (diatoms)**). - **Akinete:** Resting spores that are resistant to unfavorable conditions and are found in Cyanophyta. They are rich in food reserves that help them survive harsh conditions. - **Sexual Reproduction:** - **Gametes:** These are reproductive cells that fuse during fertilization. - **Gametangium:** This is a structure that produces gametes. - **Antheridium:** The male gametangium. - **Oogonium:** The female gametangium. - **Types of sexual reproduction:** - **Isogamy:** Gametes are identical in size and shape. - **Anisogamy:** Gametes are different in size, one is larger and passive, the other is smaller and active. - **Oogamy:** The most advanced form of sexual reproduction involving fusion of a large, non-motile, passive egg and a small, motile, active sperm. ## Algal Plastids - **Chromato Phores:** These are pigment-containing structures found in some algae. - **Chloro Plast:** Contain chlorophyll (a) and (b). - **Cyanophyta:** These algae lack chloroplasts and have only a single, specialized pigment known as **Phycocyanin**. - **Structure of a Chloroplast:** - **Stroma:** The colorless matrix that surrounds the thylakoid. - **Thylakoid:** A flattened sac-like membrane containing chlorophyll. - **Grana:** Stacks of thylakoids. ## Light and Dark Reactions in Photosynthesis - **Light Reaction:** This occurs in the **thylakoids** and involves the capturing of light energy and its conversion into chemical energy in the form of ATP and NADPH. - **Dark Reaction (Calvin Cycle):** Occurs in the **stroma** and involves the use of ATP and NADPH from the light reactions to reduce carbon dioxide and synthesize sugars. - The shape of the chloroplasts can vary between algae, which is used as a characteristic for classification. - **Shapes of Chloroplasts:** - **Spiral**: As seen in **Spirogyra**. - **Star Like:** As seen in **Zygnema**. - **Girdle**: As seen in **Ulothrix**. - **Reticulate:** As seen in **Oedogonium**. - **Cup**: As seen in **Chlamydomonas**. - **Axile:** As seen in **Maugeotia**.