Blue Green Algae & Protists PDF

# Blue Green Algae (Cyanophyta) - Cyanophyta includes a large number of algae which are characterized by a low state of cell organization. - The cells lack the well-defined nucleus that present in the other algae. - These organisms are characterized by a blue-green coloration of the cell. - The chi...

# Blue Green Algae (Cyanophyta) - Cyanophyta includes a large number of algae which are characterized by a low state of cell organization. - The cells lack the well-defined nucleus that present in the other algae. - These organisms are characterized by a blue-green coloration of the cell. - The chief pigments being chlorophyll a, carotenes, xanthophylls, C-phycoerytherin. - The product of photosynthesis glycogen. - They can withstand the most unfavorable conditions. - Some members lead a symbiotic life with fungi forming lichens. # Internal Structure - The image shows a cross-section of a blue-green algae cell. - **Nucleoid**: circular DNA - **Protein Granule**: storage of protein - **Ribosome**: protein synthesis - **Photosynthetic Lamellae**: contains chlorophyll and other pigments for photosynthesis - **Phyobisomes**: contains phycobilins, pigments that absorb light for photosynthesis - **Plasma membrane**: cell membrane - **Cell wall**: protective layer - **Gelatinous coat**: slimy outer layer # Reproduction - **Hormogonia**: short lengths of trichome with rounded ends and without differentiation of the cells. - **kinetes**: resting spores which are formed by the differentiation of the cell. - There is an obvious relation between the position of heterocysts and the place of akinetes formation. # Relationship between blue-green algae and bacteria - Some authors suggested that both bacteria and blue-green algae may be regarded as two classes of the phylum schizophyta. - **Absence of nuclei**: no membrane-bound nucleus - **Absence of sexual reproduction**: reproduce asexually - **Absence of plastids**: no specialized organelles for photosynthesis, instead, photosynthesis occurs in thylakoid membrane # Cell Structure - **Cell wall**: consists of two layers, a thin inner layer and a thick outer gelatinous layer or the cell sheath. - **Protoplast**: differentiated into two parts - **Chromatoplasm**: peripheral pigmented region - **Centroplasm**: central colorless region. # Animal-like protists (Protozoa) - Single-celled organisms regarded as having animal-like characteristics. - **Commensal**: an organism that lives in or on another organism, deriving some benefit from the association but not harming the other part. - **Metazoa**: multicellular animals - Most protozoans are found in freshwater or marine habitats, where they form a significant component of plankton. - **Phagocytosis**: ingest their food by engulfing the prey using pseudopodia or mouth-like structures. # Diagram of Animal-like Protists An image depicts a protozoan with the following labeled structures: - **Pseudopod**: temporary extension of cytoplasm used for movement and feeding - **Food vacuole**: stores food engulfed during phagocytosis - **Nucleus**: control center of the cell - **Membrane**: thin outer layer of the cell - **Contractile Vacuole**: pumps excess water out of the cell - **Endoplasm**: inner portion of cytoplasm - **Ectoplasm**: outer portion of cytoplasm # The eukaryotic cell - **Protista**: microscopic unicellular organisms that don't fit into the other kingdoms. - Some members of Kingdom Protista are unicellular, others are colonial, and yet others are multicellular. - These organisms are all eukaryotes (they have a true nucleus). - Protists are grouped into three major, unofficial categories based on means by which they obtain nutrition. These are the Protozoa, the Algae, and the Fungus-like Protists. # Plant-like Protista (The Algae) - These protists are photosynthetic: their nutrition is plant-like. Almost all of them have chlorophyll A. Most have chlorophyll C, but only a few chlorophyll B. - **Characteristics of algae**: - **Possession of the pigment chlorophyll**: chlorophyll is used for photosynthesis - **Deriving energy from the sun by means of oxygenic photosynthesis**: uses sunlight to convert carbon dioxide and water into sugars - **Fixing carbon from CO2 or dissolved bicarbonate**: convert carbon dioxide into organic compounds - **All algal types are eucaryotic**: algae have a true nucleus and membrane-bound organelles. - The internal organelles of algae includes: - nuclei - mitochondria - endoplasmic reticulum - ribosomes - Golgi body - chloroplasts (in most instances) - **With the exception of one group (the Euglenophyta), all have a cellulose cell wall**: most algae have a cell wall composed of cellulose, a complex sugar. - The cellulose cell wall is frequently modified with other polysaccharides, including pectin and alginic acids. # Division: Bacillariophyta - The members of which popularly known as diatoms. The majority are single-celled but in some the cells are united into colonies. They are found in both fresh and salt water. The chief characteristic features of this class are: - **The diploid thallus**: the vegetative diatom is diploid, containing two sets of chromosomes - **The silicified cell wall consisting of overlapping halves bearing characteristic secondary structures**: diatoms have a cell wall made of silica, which is a hard material - **Storage of food reserves as oil and chrysolaminarin. Or a protein-like food material called volutine**: diatoms store food as oil or a carbohydrate called chryslaminate - **Motile stage (sperms) with a single flagellum sometimes two**: diatoms have flagella which allow them to move - **Production of unique type of spores known as auxospores**: auxospores allow diatoms to restore their original size after cell division - **The presence of chlorophyll a and c but not b together with fucoxanthin as photosynthetic pigments**: diatoms have specific pigments that allow them to capture light. # Algae includes different groups (phyla or divisions): - **Euglenophyta**: a phylum of single-celled eukaryotic algae. - **Bacillariophyta**: a phylum of single-celled eukaryotic algae, also known as diatoms. - **Chlorophyta**: a phylum of green algae. - **Phaeophyta**: a phylum of brown algae. - **Rhodophyta**: a phylum of red algae. # Phylum: Euglenophyta - A **pellicle**: a semi-rigid structure composed of protein strips found surrounding the cell of many unicellular protozoans and algae. - Individuals range in size from 10-500 µm. - Euglenophytes are commonly found in fresh water, particularly that with a high organic content, and to a lesser extent, in soil, brackish water and salt water. - The storage product of photosynthesis is a B-1,3-linked glucan called paramylon. - **Reproduction**: - **Fission**: asexual reproduction, where the cell divides in two. - **Cyst formation**: resting stage where the cell is enclosed in a protective wall. ## Diagram of Euglena An image shows a diagram of Euglena with the following structures labeled: - **Flagellum**: long, whip-like structure used for movement - **Stigma**: light-sensitive organelle - **Reservoir**: stores water - **Nucleus**: control center of the cell - **Nucleolus**: region within the nucleus containing DNA - **Chloroplast**: organelle containing chlorophyll for photosynthesis - **Contractile Vacuole**: pumps excess water out of the cell - **Pellicle**: semi-rigid outer layer of the cell # Cell division of diatoms - **Cell division**: First is an increase in volume of frustule resulting in a slight separation of valve. - This followed by mitotic division of the nucleus with its spindle parallel to the short axis of the cell followed by longitudinal division of the protoplast resulting in the formation of two daughter protoplasts. - Thus, each daughter protoplast has the half old wall on one side and protoplasmic membrane on the other side. - The new half wall fits inside the original old half wall in the original old wall in the two newly formed cells. The old wall of the two newly formed cells forms **epitheca** and the new wall always forms **hypotheca**. - Out of the two cells one (with old epitheca) has the same size as that of the parental cell and the other (with old hypotheca) is slightly smaller. - Thus, after repeat cell division the size of diatom cell would diminish. - To restore the original size, the diatom cells form **auxospore**. ## Cell Structure - **Valve view**: seen from the top or bottom, the diatom cell is seen from the valve side, which is upper-most - **Girdle view**: seen from the side, the diatom cell is seen from the girdle side, which is upper-most - **Epitheca**: the older cell wall of the diatom - **Hypotheca**: the newer cell wall of the diatom ## Diagram of Diatom Cell Structure An image shows a diagram of a diatom cell structure in the following views: - **Valve view**: shows the top or bottom of the cell, with two halves joined together with the valve side facing upward. The valves are marked with the following structures: - **Anterior polar nodule**: top of the valve - **Posterior polar nodule**: bottom of the valve - **Central nodule**: center of the valve - **Girdle view**: shows the side view of the cell, where the overlapping bands are visible. The girdle bands contain **raphe** (a groove that runs along the cell wall) and are marked with the following structures: - **Epitheca**: upper half of the cell wall - **Hypotheca**: lower half of the cell wall ## Cell Division of Diatoms an image shows a diagram representing cell division of diatoms, starting with the most dominant cell. - **A**: the largest cell formed after the auxospore stage - **B**: the new smaller cell formed by cell division of the largest cell - **C**: an even smaller cell formed after repeated division - **D**: the smallest cell formed after repeated division - Cells produce new cells through division, each with a new cell wall or **hypotheca** and keeps the old cell wall or **epitheca**