163CellDiversity10

163CellDiversity10 - BI 163 LABORATORY COLLECTION AND...

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1 BI 163 LABORATORY COLLECTION AND OBSERVATION OF CELLS (Reviewed Fall 2010) Prokaryotes Prokaryotes are set apart from all other organ- isms because their cells lack nuclei. Phylogenetic evidence indicates that there are two very distinct groups of prokaryotes: Bacteria and Archaea. These two groups diverged from one another near the time of the origin of life! Domain Bacteria Bacteria are single-celled organisms that lack nuclei. They are also distinguished from eukaryotic organisms by some unique features of their protein synthesis. You will learn more about that later in the course. Bacteria come in a great variety of shapes and sizes (although from our perspective they are all very small!). Bacteria can be found in almost any habitat on earth. One of the most famous bacterial species is Escherichia coli (shown below), which lives in the human colon. Domain Archaea Archaea are also single-celled organisms that lack nuclei. Their protein synthesis, however, is more like that of eukaryotes than that of bacteria. Archaea come in a great variety of shapes and sizes and can be found in a great diversity of habitats. Eukaryotes Eukaryotes are organisms whose cells include a nucleus. They also contain a variety of organelles such as mitochondria and chloroplasts, which are specialized to carry out specific cellular functions. Protists Protists is a general term for unicellular eukaryotes. There are currently a number of different groups of protists, although the phylogeny of these organisms is still under revision. As would be expected, protists are a very diverse group (if they are really even a group at all). They are often placed into three categories based on their method of obtaining energy. Fungus-like protists absorb food from their surroundings. Plant-like protists (algae) are photosynthetic. And animal-like protists (protozoa) engulf food particles (i.e. “eat”). Fungi (Mushrooms, Yeasts, Molds)
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This note was uploaded on 10/06/2010 for the course ES ES271 taught by Professor Machaut during the Spring '10 term at Colby.

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163CellDiversity10 - BI 163 LABORATORY COLLECTION AND...

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