Green algae and cyanobacteria are two types of photosynthetic organisms that are evolved from algae. Both cyanobacteria and green algae are incredibly diverse organisms that are mostly found in aquatic environments. Cyanobacteria are prokaryotes, while green algae are eukaryotes. As a result, the green algae have a nucleus and membrane-bound organelles. Cyanobacteria, in contrast, lack membrane-bound organelles.
Cyanobacteria are otherwise called the blue-green algae. Both cyanobacteria and green algae are photosynthetic organisms that make their own food through photosynthesis. Heterotrophic cyanobacteria can also exist. Green algae and cyanobacteria primarily vary in that the cells of green algae include chloroplasts while the cells of cyanobacteria do not.
Similarities Between Green Algae and Cyanobacteria
- Both green algae and cyanobacteria evolved from algae.
- Both green algae and cyanobacteria are diverse organisms.
- Both green algae and cyanobacteria occur in terrestrial and aquatic habitats.
- Both cyanobacteria and green algae have the capacity to synthesize light.
- Some cyanobacteria and green algae coexist harmoniously.
- Green algae and cyanobacteria can both be single cells or multicellular organisms.
- Vacuoles are present in both cyanobacteria and green algae.
- Green algae and cyanobacteria both use starch to store food.
Differences between Green Algae and Cyanobacteria
Cyanobacteria are a group of prokaryotic bacteria that can photosynthesize. Algae, in contrast, are tiny eukaryotic organisms that resemble microscopic plants. This is the key difference between cyanobacteria and algae. One more difference between cyanobacteria and algae is that the cyanobacteria belong to kingdom Monera while algae belong to kingdom Protista.
A nucleus and membrane-bound organelles are also absent from cyanobacteria. Algae, however, have a nucleus and membrane-bound organelles. Algae and cyanobacteria differ in this way in addition to other ways. The ability to fix atmospheric nitrogen by cyanobacteria as opposed to algae is maybe the most significant difference.
1. Definition
Green Algae: Green algae refer to any green color algae found in freshwater habitats.
Cyanobacteria: Cyanobacteria refer to any photosynthetic bacteria, which often form colonies in the form of filaments, spheres or sheets and occur in diverse environments.
2. Type
Green Algae: Green algae are eukaryotes.
Cyanobacteria: Cyanobacteria are prokaryotes.
3. Membrane-bound Organelles
Green Algae: Green algae consist of membrane-bound organelles.
Cyanobacteria: Cyanobacteria lack membrane-bound organelles.
4. Chloroplasts
Green Algae: Green algae contain one or more chloroplast per cell.
Cyanobacteria: Cyanobacteria do not contain chloroplasts.
5. Photosynthetic Pigments
Green Algae: Green algae contain chlorophyll a, chlorophyll b, carotenoids, and xanthophyll as photosynthetic pigments.
Cyanobacteria: Cyanobacteria contain chlorophyll a, phycoerythrin and phycocyanin as photosynthetic pigments.
6. Under the Light Microscope
Green Algae: Green algae can be identified by the presence of chloroplasts in the cells.
Cyanobacteria: Cyanobacteria exhibit a homogeneous color throughout the cell.
7. Mode of Nutrition
Green Algae: Green algae are photoautotrophs.
Cyanobacteria: Cyanobacteria are either photoautotrophs or heterotrophs.
8. Nitrogen Fixation
Green Algae: Green algae do not fix gaseous nitrogen.
Cyanobacteria: Cyanobacteria are involved in the nitrogen fixation by utilizing gaseous nitrogen as a nutrient.
9. Storage of Nutrients
Green Algae: Green algae have less ability to store nutrients.
Cyanobacteria: Cyanobacteria show an efficient storage of nutrients.
10. Swimming
Green Algae: Green algae can swim through water.
Cyanobacteria: Cyanobacteria cannot swim but, they can alter their buoyancy, changing the depth in water.
11. Asexual Reproduction
Green Algae: The asexual reproduction of green algae occur by fission, budding, fragmentation or by the formation of zoospores.
Cyanobacteria: The asexual reproduction of cyanobacteria occurs by cell division and the formation of a plate, separating the two cells.
12. Sexual Reproduction
Green Algae: The sexual reproduction of green algae occurs by the formation of gametes.
Cyanobacteria: Cyanobacteria do not undergo sexual reproduction.
Tabular Differences between Algae and Cyanobacteria
| Green Algae | Cyanobacteria |
| Belongs to kingdom protista | Belongs to kingdom Monera |
| Eukaryotes | Prokaryotes |
| Contain one or more chloroplasts per cell. | Do not contain chloroplasts. |
| Consists of membrane-bound organelles | Do not consist of membrane-bound organelles |
| Photoautotrophs | Photoautotrophs or heterotrophs |
| Have less ability to store nutrients. | Shows an efficient storage of nutrients. |
| Can swim through water. | Cannot swim through water but can alter their buoyancy, changing the depths in water. |
| Sexually reproduce by the production of gametes. | Does not reproduce sexually. |
| Asexual reproduction methods include fission, budding, fragmentation and formation of zoospores. | Asexual reproduction method includes cell division and the formation of a plate, separating the two cells. |
| Not involved in nitrogen fixation. | Involved in nitrogen fixation. |
| Contains chlorophyll a, chlorophyll b , carotenoids and xanthophyll as photosynthetic pigments. | Contains chlorophyll a, phycoerythrin and phycocyanin as photosynthetic pigments.. |
| Examples are Spirogyra, Chlamydomonas, Chlorella and green seaweeds. | Examples are Nostac, Spirulna and Anabaena. |
Conclusion
Algae and cyanobacteria are photosynthesis-producing organisms. The main distinction between cyanobacteria and algae is that algae are eukaryotic organisms, whereas cyanobacteria are prokaryotic organisms.
In addition, cyanobacteria lack membrane-bound organelles and a true nucleus. However, algae have a true nucleus as well as membrane-bound organelles like mitochondria and chloroplasts. Additionally, while algae have chlorophylls a and b, carotenoids, and xanthophylls, cyanobacteria contain chlorophyll a, phycocyanin, and phycoerythrin.