write the characters of dinoflagellutes
Answers
Answer:
Neither plant nor animal, dinoflagellates are unicellular protists; most exhibit the following characteristics:
- They are planktonic.
Ninety percent of all dinoflagellates are marine plankton. Others are benthic, symbiotic, or parasitic.
- They are small.
Although many of them are microscopic and range from 15 to 40 microns in size, the largest,Noctiluca, may be as large as 2 mm in diameter!
- They are motile.
Dinoflagellates swim by means of two flagella, movable protein and microtubule strands that propel the cell through the water. The longitudinal flagellum extends out from the sulcal groove of the hypotheca (posterior part of cell); when it whips back and forth it propels the cell forward. The flattened transverse flagellum lies in the cingulum, the groove that extends around the equator of the cell. Its motion provides maneuvering and forward movement. As a result of the action of the two flagella the cell spirals as it moves.
- Many are thecate, having an internal skeleton of cellulose-like plates.
The peripheral part of the cell has a series of membranes called the amphiesma. In “armored” species polysaccharide deposited between the membranes forms rigid plates called thecae. “Naked” cells lack thecae.
- Their chromosomes are always condensed.
Dinoflagellate DNA always exists in a crystalline form in the nucleus, unlike other eukaryotes. In addition, lack proteins called histones that in other eukaryotic cells helps organize the chromosomes. Dinoflagellates contain a lot of DNA, which explains the large size of the nucleus. The metabolic requirements of supporting the large amount of DNA may explain the low growth rates of dinoflagellates compared to other unicellular protists.
- Not all dinoflagellates are photosynthetic.
Many dinoflagellates are photosynthetic, manufacturing their own food using the energy from sunlight, and providing a food source for other organisms. The photosynthetic dinoflagellates are important primary producers in coastal waters.Some photosynthetic dinoflagellates are symbiotic, living in the cells of their hosts, such as corals.
- Dinoflagellates usually reproduce asexually.
The most form of reproduction is asexual, where daughter cells form by simple mitosis and division of the cell. The daughter cells will be genetically identical to that of the original cell. The thecal plates may either be divided, or completely shed and then reformed.
Hope this helps...!! : )
Explanation:
Following are the main characters of Dinoflagellates: Dinoflagellates are basically unicellular motile and biflagellate, golden brown, photosynthetic protists. The predominant colour is golden brown but yellow, green, brown and even blue forms also occur due to change in the proportion of various pigments.