What is the evolutionary pressure that caused polynucleated cells to form in some protists?

Question

I also would like to know (and this may be cheating asking another question here but...) Does each nucleus contain an identical set of DNA? How does mitosis work with these little guys??? Thanks!!!!

Answer 1

Great question! And no, I won't call it cheating if you add another follow-up query. It's good to be inquisitive.

Now, to answer your question precisely, there was no evolutionary pressure that caused polynucleated cells to form in protists as such. The factors that affect evolution viz. natural selection, genetic drift, gene migration, recombination and mutation cannot (with the exception of mutation) cause the appearance of a certain morphological trait as effectively as they can help the organism to sustain it.

The answer actually lies in the second question you asked. Yes, mitosis. To state it briefly, yes, each nucleus *does* contain an identical set of DNA.

The reason why cells are different functionally in multicellular organisms is because of the effects of certain gene mechanisms that "switch off" and "switch on" the production of enzymes under specific conditions thus, altering their functionality.

Now, to answer your primary query-- as you already might be aware that during the cell-division, it is the nucleus that first divides into two: (Mitosis). Sometimes, the outer membrane of the protist fails to separate due to the lack of phospholipid membrane material. This delay in cell division back in the days of the beginning might have resulted in a polynucleated cell.

The success of this polynucleated cell may be easily justified due to the increased efficiency of the metabolism as the decentralisation of regulating power i.e. nuclear material could have resulted in division of labour and thus, in perhaps the first *ever* "pseudo"-multicellular animal.

As for your follow-up queries, I think I have provided enough detail in the paragraph above, which you can use as a *very* basic outline and explore the subject further by studying the topic in detail in your book(s).

Answer 2

This is purely a guess.

Off the top of my head, the only polynucleated cell that I can think of are skeletal muscle cells. As you know, they are very long and would need to get instructions from the nucleus through out the cell. It would seem that having a polynucleated cell would increase the efficiency of tRNA.

It is also my understanding that each nucleus does contain the whole all chromosomes

Answer 3

it somewhat is what it somewhat is - if people have developed to the element that we are able to amplify our lives extra and administration ailment, then this is all part of evolution. in spite of the undeniable fact that, i do no longer see how we are able to truly evolve as a species any extra thinking how great the gene pool is. Evolution happens over long sessions the place mutations have a wager to propagate, and with lots of genes interior the pool, any mutations that are effective won't have an substantial effect on the inhabitants as an entire.

Answer 4

I would guess that a virus caused it.