Prokaryote vs, Eukaryote cells (Introduction)

by David Turell , Thursday, May 07, 2015, 02:16 (3488 days ago)

Bacteria are eukaryotes, no nucleus. Eukaryotes are much more complex and have a nucleus. Just how did the change occur?:-http://www.evolutionnews.org/2015/05/at_the_dawn_of095801.html-
"I am not telling you this to give you a short course in cell biology, but to illustrate how different the cell types are. The details I have described represent some of the white spaces in the evolutionary story that must be accounted for if evolution by undirected processes is true. Stories exist for how mitochondria and chloroplasts came to be present in eukaryotic cells -- they mainly involve the incorporation of ancient bacteria into the incipient eukaryotic cell. The proposed process has been given the name endosymbiosis. There is no single proposed mechanism for the evolution of the nucleus or the other structures I have named. -"I deliberately call such evolutionary accounts "stories." To become a eukaryote like C. reinhardtii involves enormous changes in cell organization that affect every aspect of cellular life. Most of these structures are common to eukaryotic cells, and most are membrane-bound. Membranes mean there must be transport mechanisms in or out of each compartment. DNA replication and division becomes more complicated because the nuclear membrane must break down and reform at each division. Nuclear genes have somehow come to specify proteins necessary for mitochondrial function; they must be transcribed, the RNA exported to the cytoplasm, made into protein, and then the proteins must be transported into the mitochondrion. Specific problems associated with the replication of chromosomes versus circular DNA as in bacteria have to solved. There are more differences to be dealt with than I can cover -- exons and introns, and the separation of mRNA production in the nucleus from protein synthesis in the cytoplasm, just to name two. All of these problems must be solved somehow if the story of undirected evolution is true.-"How many new steps were needed to accomplish all this? Even if it happened one organelle at a time, that it happened at all is a wonder. And all this had to happen before the appearance of multicellular animals, since animals and plants have these structures in common.-"These are some of the things Darwin didn't know, but now we do. I wonder what Darwin would have said if he had known these details."