Why are the dinoflagellates mesokaryotes?
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) The Dinoflagellates have been referred to as mesokaryotes because they have some "nuclear" features that appear to be intermediate between those of prokaryotes and eukaryotes
(2) They have nuclear envelopes (membranes), although (unlike the situation in higher plant cells) these membranes don't break down completely during mitosis.
(3) They have DNA organized into chromosomes, but these chromosomes are always condensed (never extended as during interphase in higher plant cells) and the chromosomes do not have a histone protein component
(4) Both the dinoflagellates and the diatoms have sexual reproduction which is accomplished by the production of motile haploid gametes (eggs and sperms) which fuse to form a diploid zygote. The gametes require a water medium to move around in (and find each other) but because these organisms live their entire lives in water this is not a problem. The zygote is a "resting" stage which subsequently becomes active to start the next generation. There are differences in the primitive life cycles of these organisms.
(5) Dinoflagellates are haploid organisms. Therefore, their gametes are produced by mitotic divisions of their nuclei. As the diploid nucleus of the zygote becomes active it undergoes meiosis to create the haploid nucleus of the free-living organism.
(2) They have nuclear envelopes (membranes), although (unlike the situation in higher plant cells) these membranes don't break down completely during mitosis.
(3) They have DNA organized into chromosomes, but these chromosomes are always condensed (never extended as during interphase in higher plant cells) and the chromosomes do not have a histone protein component
(4) Both the dinoflagellates and the diatoms have sexual reproduction which is accomplished by the production of motile haploid gametes (eggs and sperms) which fuse to form a diploid zygote. The gametes require a water medium to move around in (and find each other) but because these organisms live their entire lives in water this is not a problem. The zygote is a "resting" stage which subsequently becomes active to start the next generation. There are differences in the primitive life cycles of these organisms.
(5) Dinoflagellates are haploid organisms. Therefore, their gametes are produced by mitotic divisions of their nuclei. As the diploid nucleus of the zygote becomes active it undergoes meiosis to create the haploid nucleus of the free-living organism.
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