علم الطحالب الزرقاء والخضراء

Study Notes

Includes a large number of algae, characterized by a specific cellular organization.
Cells lack a well-defined nucleus.
Characterized by a blue-green coloration from pigments like chlorophyll, carotenoids, and xanthophylls.
Photosynthesis product is glycogen.
Tolerant of varied conditions.
Some species form symbiotic relationships with fungi (lichens).
Have a relationship with bacteria.
Classified as a separate phylum (Schizophyta).
Lack of nuclei, sexual reproduction, and plastids.

Cell wall composed of two layers: thin inner and thick outer gelatinous layer (cell sheath).
Internal structure includes a peripheral pigmented region (chromatoplasm) and a central colorless region (centroplasm).
Possess plasma membrane, protein granules, and circular DNA (nucleoid).
Ribosomes, photosynthetic lamellae, and phycobilisomes (cyanosomes).
Reproduction through hormogonia.

Relationship between heterocysts' position and kinete formation location is evident.

Some species, like Nostoc, Oscillatoria, Scytonema, and Spirulina, are used to improve soil fertility.
Certain species produce toxins that pollute water.

Single-celled organisms with animal-like characteristics.
Commensalistic—living in association with or in other organisms.
Diverse habitats, including freshwater and marine ecosystems, frequently found in plankton.
Ingest food through phagocytosis (some have mouthlike structures for consuming prey, others using pseudopods).
Possess structures for movement and feeding (e.g., food vacuoles, contractile vacuoles).

Photosynthetic; their nutrition is plant-like.
Possess chlorophyll a (and some have chlorophyll b, c)
Derive energy through oxygenic photosynthesis.
Acquire carbon from dissolved bicarbonates.
Eukaryotic organisms with internal structures like mitochondria, endoplasmic reticulum, ribosomes, and Golgi bodies, and in most cases, chloroplasts.
Cell walls are primarily composed of cellulose (in most cases) with variations in other polysaccharides (pectin and alginic acids).
Examples of algal phyla: Euglenophyta, Bacillariophyta, Chlorophyta, Phaeophyta, and Rhodophyta.

Semirigid pellicle composed of protein strips.
Size range from 10-500 µm.
Predominantly freshwater, found in various environments including high organic content water and even soil, brackish, or salt waters.
Storage product of photosynthesis is a β-1,3-linked glucan called paramylon.
Reproduction through fission and cyst formation.

Members are commonly known as diatoms.
Single-celled or colonial, found in various waters (both fresh and salt).
Cell walls are composed of silica (silicified).
Characterized by overlapping halves (valves) that form a unique structure.
Store photosynthetic products as lipids or oils, and protein-like substances (chrysolaminarin).
Motile stage, sometimes seen in some species, involves a single flagellum.
Can produce unique spore types known as autospores.
Cell walls contain photosynthetic pigments like chlorophyll a and c, along with fucoxanthin.
Cell structure described in valve and girdle views.

Initial volume increase in the frustule (cell wall) results in slight valve separation.
Nuclei undergo mitotic division.
The resulting spindle is parallel to the cell's short axis.
Longitudinal division of the chloroplast forms two daughter protoplasts.
Each daughter protoplast receives half of the old cell wall (the hypotheca for one and epitheca for the other).
The formed cell (with the old epitheca) retains the same size as the original cell, while the cell with the old hypotheca is slightly smaller.
Repeated cell division leads to a decrease in the overall size of diatoms.