What are the main characteristics of prokaryotic and eukaryotic cells?
Biologists recognize 2 basic cell types: prokaryotic and eukaryotic. The earliest cells on earth were relatively simple prokaryotic cells. Over billions of years, some of these early prokaryotic cells evolved into present-day prokaryotic cells, while others evolved into much larger and more complex eukaryotic cells. Both types of cells have genetic material in the form of DNA; a thin, flexible, plasma membrane which surrounds the semi-fluid contents of the cell called the cytoplasm; and specialized structures within the cytoplasm called organelles. In addition, both types of cells may have a thick, rigid cell wall surrounding the plasma membrane.
In terms of differences, eukaryotic cells are much larger and more complex than prokaryotic cells. On average, a typical eukaryotic cell is about 1,000 X larger in volume than a typical prokaryotic cell. Because of their much larger size, eukaryotic cells generally have much more DNA than prokaryotic cells, and there is a much greater degree of compartmentalization and division of labor within a eukaryotic cell. The interior of eukaryotic cells is generally divided into many specialized compartments by internal membranes (membranes separate from the plasma membrane) and membrane-bound organelles (organelles completely surrounded by membranes). Usually, prokaryotic cells lack internal membranes and membrane-bound organelles. In addition, the DNA of eukaryotic cells is enclosed within a membrane-bound nucleus, while the DNA of prokaryotic cells is located in the cytoplasm.
During this lab, you will use the brightfield microscope to examine and compare the features of several types of prokaryotic cells, and several types of eukaryotic cells.
Use the interactive exercise below to identify the structures found in typical prokaryotic and eukaryotic cells.
|Indicate which type(s) of cells each of the following characteristics applies to by writing “P” for prokaryotic cells only, “E” for eukaryotic cells only, “B” for both, or “N” for neither.|
|Lack a plasma membrane||Check your answer.|
|Contain cytoplasm||Check your answer.|
|Contain genetic material in the form of DNA||Check your answer.|
|Contain a membrane-bound nucleus||Check your answer.|
|Contain specialized structures called organelles||Check your answer.|
|Usually lack membrane-bound organelles||Check your answer.|
|May have a rigid cell wall surrounding the plasma membrane||Check your answer.|
|Interior is generally divided into many specialized compartments by internal membranes||Check your answer.|
|First type of cells to evolve on our planet||Check your answer.|
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