Question

Dinoflagellates have a mesokaryotic cell organization. Which of the following features is not related to such cellular organization?
A. Single nuclear membrane
B. No spindle formation
C. Presence of histones
D. Permanently condensed chromosomes

Answer 1

Hint: The continuous coiling, shortening, and thickening of chromosomes to become more visible under the light that is a specific characteristic feature of the dinoflagellates showing them to be in between the primitive and the advanced cell type.

Complete answer:
Dinoflagellates are the single-celled mesokaryotic organisms that belong to the phylum Dinoflagellata. Mesokaryotes are the organisms that were used to be considered in between the nucleoid of the prokaryotes and the nucleus of the eukaryotes and their nucleus do not contain histones proteins instead a new family of proteins called viral nucleoproteins.

Additional Information:
-Dinoflagellates are mostly marine organisms that may also be found in the freshwater habitats.
-These organisms are said to be photosynthetic or sometimes mixotrophic, a type of nutrition where various sources of energy are utilized.
-The accumulation of these organisms over various water bodies may result in the formation of red tide, also called a harmful algal bloom.
-The harmful red tide causes toxicity in the shellfish living in that water body which if consumed by humans may cause shellfish poisoning.
-Some dinoflagellates are known for their property of bioluminescence, where they emit blue-green light.
-It is found in the Indian ocean, which gives blue-green at night.
-The mesokaryotic organisms are those which differ based on the presence of their nucleus.
-Earlier these organisms were said to be prokaryotes but later after several studies, they were included in the advanced organisms.
-The chromosomes in these organisms remain condensed throughout the interphase and do not form the spindle fibers as in mitosis.
-They do not have histone proteins instead they have dinoflagellate/viral nucleoproteins.
So, the correct answer is ‘Presence of Histones’.

Note: Histones are the basic proteins that are found in the nuclei of the eukaryotic cells which pack the DNA molecules into a structural complex called nucleosomes. The term dinoflagellate was derived from the Greek word dinos, meaning ‘whirling’, and also from the Latin word flagellum, meaning ‘a whip or scourge’. The first modern dinoflagellates were described by Henry Baker in 1753. It was named in 1773 by Otto Friedrich Müller.