- What is the peptidoglycan layer and how does it differ between gram-positive and gram-negative bacteria?
- Compare and contrast monotrichous, amphitrichous, lophotrichous, or peritrichous flagella.
3.4 Unique Characteristics of Eukaryotic Cells
Learning Objectives
- Explain the distinguishing characteristics of eukaryotic cells
- Describe internal and external structures of prokaryotic cells in terms of their physical structure, chemical
structure, and function - Identify and describe structures and organelles unique to eukaryotic cells
- Compare and contrast similar structures found in prokaryotic and eukaryotic cells
Eukaryotic organisms include protozoans, algae, fungi, plants, and animals. Some eukaryotic cells are independent,
single-celled microorganisms, whereas others are part of multicellular organisms. The cells of eukaryotic organisms
have several distinguishing characteristics. Above all, eukaryotic cells are defined by the presence of a nucleus
surrounded by a complex nuclear membrane. Also, eukaryotic cells are characterized by the presence of membrane-
bound organelles in the cytoplasm. Organelles such as mitochondria, the endoplasmic reticulum (ER), Golgi
apparatus, lysosomes, and peroxisomes are held in place by thecytoskeleton, an internal network that supports
transport of intracellular components and helps maintain cell shape (Figure 3.36). The genome of eukaryotic
cells is packaged in multiple, rod-shaped chromosomes as opposed to the single, circular-shaped chromosome that
characterizes most prokaryotic cells.Table 3.2compares the characteristics of eukaryotic cell structures with those
of bacteria and archaea.
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