Evolution of Eukaryotes

Evolution of Eukaryotes - alternation of generations found...

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Evolution of Eukaryotes | The transition to eukaryotic cells appears to have occurred during the Proterozoic Era, about 1.2 to 1.5 billion years ago. However, recent genetic studies suggest eukaryotes diverged from prokaryotes closer to 2 billion years ago. Fossils do not yet agree with this date. The old Kingdom Protista, as I learned it long ago, thus contains some living groups that might serve as possible models for the early eukaryotes. This taxonomic kingdom has been broken into many new kingdoms, reflecting new studies and techniques that help elucidate the true phylogenetic sequence of life on Earth. Protists exhibit a great deal of variation in their life histories (life cycles). They exhibit an alternation between diploid and haploid phases that is similar to the
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Unformatted text preview: alternation of generations found in plants. Protist life cycles vary from diploid dominant, to haploid dominant. A generalized eukaryote life cycle is shown in Figure 1. The great diversity of form, habitat, mode of nutrition, and life history exhibited by eukaryotes suggests they evolved several times from various groups of prokaryotes. This makes the Protista a polyphyletic group. Eukaryotes are generally larger, have a variety of membrane-bound organelles, greater internal complexity than prokaryotic cells, and has a secialized method of cell division ( meiosis ) that is a prelude to true sexual reproduction. Protists might be viewed as a group from which the other eukaryotic kingdoms evolved, as shown by Figure 2....
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This note was uploaded on 11/29/2011 for the course BIO BSC1010 taught by Professor Gwenhauner during the Fall '10 term at Broward College.

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Evolution of Eukaryotes - alternation of generations found...

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