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IVSAT 2024

Microorganisms are something that goes beyond the human eyes and these need special instruments through which they can be perceived. One of these microorganisms that needs an instrument to be seen through is Chlamydomonas. Chlamydomonas is a genus that consists of at least 325 species of unicellular green algae. These are found commonly in seawater, stagnant water, freshwater, and even in moist soil. To learn more about the Chlamydomonas - Meaning, Structure, Life Cycle, Function, and FAQs students can refer to Vedantu and check out all about the topic.

Chlamydomonas is a genus of green algae with about 325 members that are all unicellular flagellates found in stagnant water, moist soil, freshwater, seawater, and even snow as "snow algae." Chlamydomonas is a model organism for molecular biology research, especially for the studies of flagellar motility, chloroplast dynamics, biogenesis, and genetics. Chlamydomonas have ion channels (channelrhodopsins) that are directly activated by light, which is one of its many distinguishing characteristics. 

Chlamydomonas regulatory systems are more complex than Gymnosperm homologs, with evolutionarily related regulatory proteins being larger and possessing more domains. Chlamydomonas plant-animal that is still related to the two kingdoms' last shared ancestor. For decades, green yeast has been a resident of the laboratory. It has a fascinating morphology and behavior and is easy to develop in liquid cultures.


Structure of Chlamydomonas

Chlamydomonas algae is a green alga that is unicellular and motile. Chlamydomonas structure is a single cell used to represent the thallus. It measures approximately 20 p,-30|i in length and 20 p,-30|i in diameter. Thallus may be circular, rectangular, oblong, ellipsoidal, or pyriform in shape. The pyriform or pear-shaped thalli, which have a narrow anterior end and a wide posterior end, are normal. Their shape is oval, spherical, or pyriform. The cell is surrounded by a cellulose cell wall that is thin and firm. Between the cell membrane and the chloroplast is the cytoplasm. The cell has a huge dark nucleus that is located within the cup-shaped chloroplast cavity. Two flagella are found in the cell's anterior region, which aids in locomotion. Every flagellum has two contractile vacuoles at the base. A small red eyespot can be found on the chloroplast's anterior side. Given below is the Chlamydomonas structure with labels. 


The Life Cycle of Chlamydomonas 

Chlamydomonas Reproduction is both sexual as well as asexual reproduction.

Asexual reproduction takes place by following methods:

1. Zoospore Formation: The protoplast separates from the cell wall as it contracts. The parent cell loses its flagella, or in certain Chlamydomonas species, the flagella are absorbed. The neuro-motor apparatus and contractile vacuoles vanish. Simple mitotic division divides the protoplasm longitudinally, resulting in two daughter protoplasts. The protoplasm's second longitudinal division occurs at a right angle to the first, resulting in four daughter chloroplasts. The protoplasm will often divide again, resulting in 8-16-32 daughter protoplasts. 


Pyrenoids and neuro-motor apparatus initials also divide. Daughter protoplasts also form contractile vacuoles. Each daughter cell develops its cell wall, flagella, and zoospore. Gelatinization or rupture of the cell wall liberates the zoospores from the parent cell or zoosporangium. The zoospores have the same structure as the parent cell but are smaller. To mature Chlamydomonas, the zoospores enlarge. The formation of zoospores will occur every 25 hours under ideal conditions.


2. Aplanospores Formation: Flagella are lost by the parent cell. The protoplast is rounded on the outside and secretes a thin wall, but it lacks pore flagella. Aplanospores are these non-motile structures. Aplanospores can germinate directly or divide to produce zoospores as favorable conditions approach.


3. Hypnospores Formation: In severe unfavorable conditions, the protoplast forms a thick wall, which is known as Hypnos pore. On the approach of favorable conditions, hypnospores germinate similarly to aplanospores.


4. Palmella stage: Under unfavorable circumstances, such as a lack of water or an abundance of salts, the palmella stage develops. The parent cell's protoplast divides into several daughter protoplasts, but none of them forms zoospores. A mucilaginous sheath forms around daughter protoplasts as the parent cell wall gelatinizes. The daughter protoplasts form a gelatinous wall around themselves as well, but they lack flagella. Palmellospores are the protoplast segments that make up the palm. The division and red visions of these protoplasts eventually result in the formation of an amorphous colony with an infinite number of spores, which is known as the palmella stage. The gelatinous wall is removed, palmettosports produce flagella, and the spores are released to form new thalli when favorable conditions return.


Sexual Reproduction: Sexual reproduction in Chlamydomonas may be isogamous, anisogamous, or oogamous. The thallus can be homothallic or heterothallic, The gametes can be naked (gymnogametes) or protected by the cell wall.

  • Isogamy: The fusing pairs of gametes are nude and of similar size in this situation. 

  • Anisogamy: The fusing pairs, in this case, are identical in form but different in scale. Four larger macrogametes are produced by the female cell. Eight smaller microgametes are produced by the male cell.

  • Oogamy: The vegetative thallus, which is acting as a female cell, removes its flagella and acts as a non-motile macrogamete or egg. Pyrenoids are abundant in the female gamete. 


Chlamydomonas Classification

The Chlamydomonas is classified under these categories.

  • Chlamydomonas acidophila

  • Chlamydomonas caudata Wille

  • Chlamydomonas moewusii

  • Chlamydomonas nivalis

  • Chlamydomonas ovoidae

  • Chlamydomonas reinhardtii


Chlamydomonas Characteristics

The unicellular, pear-shaped, and biflagellate plant body is unicellular, pear-shaped, and biflagellate. Each cell has two contractile vacuoles, one eye-spot, and a cup-shaped chloroplast. Palmella-stage is present. Biflagellate zoospore formation is used for asexual reproduction. Iso-, aniso- and oogamy are all forms of sexual reproduction.


Chlamydomonas Function

Chlamydomonas is a model organism for research into flagellar motility, chloroplast dynamics, biogenesis, and genetics. Chlamydomonas have ion channels (channelrhodopsins) that are directly activated by light, which is one of its many distinguishing features.

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FAQs on Chlamydomonas

1. Explain the Habitat of Chlamydomonas.

A papilla may or may not be present in unicellular cells that are spherical or slightly cylindrical. Chloroplasts are commonly green and cup-shaped. The genus's two anterior flagella, one as long as the other, are distinguishing characteristics. Chlamydomonas can be found in both freshwater and damp soil. It is usually found in an ammonium-rich setting. Chlamydomonas is a genus of green algae with about 325 members that are all unicellular flagellates found in stagnant water, moist soil, freshwater, seawater, and even snow as "snow algae."

2. What are Chlamydomonas and What Do Chlamydomonas Do?

Chlamydomonas is a unicellular green algae genus (Chlorophyta). This genus of algae has a cell wall, a chloroplast, a "chin" that detects light, and two anterior flagella with which they can swim in a breast-stroke motion. The function of carbonic anhydrase (CA) in eukaryotic CCMs has been established using Chlamydomonas as a model organism. CA facilitates the transport and aggregation of carbonate species within specific organelles by catalyzing the interconversion of CO2 and HCO3.

3. What happens during the germination of the zygote in the Chlamydomonas?

During the germination of a zygote, the diploid nucleus of the zygote will undergo meiosis in order to form 4 haploid nuclei. The four daughter protoplasts each have a single haploid nucleus then form four haploid zoospores or meiozoospores. Each zoospore will contain neuro-motor apparatus, an eyespot, two flagella, and a contractile vacuole. In 4 of the zoospores, there may be 2 of (+) types and the other two will be of (-) types present in heterothallic forms. The number of meiospores that are present per zygospore is 8 in C. reinhardtii while it is 16 to 32 in C. intermedia.

4. What are the various species of Chlamydomonas that have been noted down in the literature?

Some of the few known species of Chlamydomonas that are known through the literature can be provided as follows:

  1. Chlamydomonas acidophila: This species is an acid-tolerant microalga that is associated with freshwater habitats.

  2. Chlamydomonas Caudata: This species is a freshwater type with an unusual arrangement of daughter cells.

  3. Chlamydomonas ehrenbergii: Found in freshwater mostly in the United Kingdom.

  4. Chlamydomonas elegans: First discovered in 1915

  5. Chlamydomonas moewusii: terrestrial living species within moist soils. Used as a model for the study of hydrogen evolution.

5. How to study all about the Chlamydomonas - Meaning, Structure, Life Cycle, Function, and FAQs through Vedantu?

Chlamydomonas - Meaning, Structure, Life Cycle, Function, and FAQs can be quite a tough topic for students who are learning about the same for the first time. But students who are preparing for the exam need not worry as they can refer to the Vedantu NCERT Solutions for Biology. This solution will contain all the details that are necessary related to the topic Chlamydomonas and hence providing a sound knowledge about the same to the students who are preparing for the exams. 

6. What is the nature of the zygote or zygospore in the Chlamydomonas?

The zygote is characterized as a resting diploid spore. The zygote tends to secrete a thick wall that is smooth or ornamented. The zygote also accumulates a large number of oils and starch. The zygospores survive long periods of unfavorable conditions and germinate when the season becomes favorable. This zygospore is red in color as it consists of the haematochrome. When the resting period has concluded and the favorable conditions are back, that is when the zygospore germinated in which the diploid nucleus tends to divide by meiosis to form haploid nuclei.

7. What are some of the important features of the Chlamydomonas?

The features of the Chlamydomonas can be provided as follows:

  1. It has a unicellular biflagellate and pear shaped body

  2. Each cell will usually have a cup-shaped chloroplast along with one eyespot and two contractile vacuoles.

  3. Sexual reproduction occurs through isogamy, oogamy, and anisogamy.

  4. There is the presence of palmella stage

  5. Asexual reproduction is processed via biflagellate zoospore formation.

  6. The cytoplasm consists of the nucleus, mitochondria, E.R, ribosomes, Golgi apparatus, etc. These nuclei are present in the cavity of the chloroplast.

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