Final answer:
When considering characteristics not observed in prokaryotes, it is important to note that prokaryotic cells do not have a highly structured cytoplasm or an endoplasmic reticulum; these are features of eukaryotic cells.
Step-by-step explanation:
The question asks which characteristics are not observed in prokaryotes. Prokaryotic cells are unicellular organisms without organelles enclosed by membranes. Consequently, they lack a nucleus, instead having their genetic material in a nucleoid. They do have a cell wall, which gives them shape and protection, as well as a plasma membrane, cytoplasm, ribosomes, and in some cases, other structures like flagella, pili, and a protective capsule. However, prokaryotes do not have a highly structured cytoplasm or an endoplasmic reticulum, which are characteristic of eukaryotic cells.