Lab 2- Bio 201
1
Name: _____________________
Prokaryotic and
Eukaryotic Cells
OBJECTIVES
• To explore cell structure and morphology in prokaryotes and eukaryotes.
• To gain more experience using the microscope.
• To obtain a better understanding of these terms: prokaryote, eukaryote, cell, cell membrane, cell wall,
nucleus, plastids, et al.
• Give two general characteristics of prokaryotic cells.
• Distinguish among the three morphological types of bacteria.
• Describe the subcellular structure of a typical bacterium.
• Identify cellular structures of a typical plant cell.
• Identify cellular structures of a typical animal cell.
Understanding the nature of cell structure and function is important to an understanding of organisms.
All organisms are composed of cells, whether they exist as single cells, colonies of cells, or in multicellular
form. Cells are usually very small, and for this reason, a thorough understanding of subcellular structure
and function has been possible only through advances in electron microscopy and molecular biology.
There are two general types of cells: prokaryotic and eukaryotic. These two words have their root in
the Greek word karyon (nut), which refers to a cell's nucleus. The prefix pro- means "before" or "prior to."
Thus prokaryotic means "before having a nucleus." Prokaryotic cells do not have a membrane-bound
nucleus and their genetic material (DNA) is only loosely confined to a nuclear area within the cell.
Bacteria, including the cyanobacteria (formerly known as blue-green algae), are prokaryotes. All other
organisms are eukaryotes. The prefix eu- means "true." The cells of eukaryotes have true,
membrane-bound nuclei containing their genetic material.
Prokaryotic and eukaryotic cells also differ in several other ways. Eukaryotic cells are generally larger and
contain additional specialized compartments (membrane-bounded organelles) in which cell
functions such as energy production may occur Prokaryotic cells lack membrane-bound organelles; their
cell functions are carried out in the cytoplasm.
During this laboratory you will investigate some of the structural of prokaryotic and eukaryotic cells. We
are going to focus on the simple differences between eukaryotes and prokaryotes in Bio 201. We will
cover the prokaryotes in much more detail in Bio 203.
PROCEDURE
Part A: Prokaryotic Cells
Part 1: Observing Bacteria
Most prokaryotic cells are extremely small (approximately 1 to 2 µm in diameter). Most are heterotrophic,
depending on preformed food, but some are autotrophic and make their own food. Morphologically,
bacteria are either round (coccus), rod-shaped (bacillus), or spiral-shaped (spirillum). To view them
with the compound microscope, you must use an oil-immersion lens (100x objective). Even then, not
much more than their basic shapes will be visible. With the aid of the electron microscope, however, you
can study these prokaryotic cells more closely. You can even use special staining techniques to learn about
their structure.
