Protists and the Dawn of the Eukarya

Kwame's illness began with a fever and shaking chills, followed by muscle aches, nausea, and vomiting. The child's kidneys failed, he developed seizures and went into a coma, and finally he died. Every 30 seconds, malaria kills someone somewhere—usually in sub-Saharan Africa, although malaria occurs in more than 100 countries and territories. About 600 million people have this disease.

Mosquitoes carry the malaria pathogen from person to person. This pathogen is not a bacterium—rather, it is a tiny eukaryote, Plasmodium falciparum. Probably the most obvious visible difference between it and the prokaryotes is that Plasmodium has numerous compartments—membrane-enclosed organelles that perform specialized functions. This single-celled pathogen has a cytoskeleton, a nucleus enclosed by a nuclear envelope, and several kinds of organelles. As a member of the domain Eukarya, it differs from members of the two prokaryotic domains in other important ways as well.

The flexibility and options that arose once the eu-karyotic cell had evolved resulted in a profusion of body forms and myriad specialized functions. Eukaryotic evolution has produced great diversity, especially among the multicellular clades, but even among the unicellular members of the domain. In both multicellular and unicellular forms, however, there are also many cases of convergent evolution; for example, organisms with an amoeba-like body form arose several times. These various amoebas are examples of organisms called protists.

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Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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