What structural elements are characteristic of all cells?

First you need to remember that there are two types of cells. Prokaryotes do not have any membrane organelles in their structure. Eukaryotes evolved from prokaryotes and received many different membrane organelles. In eukaryotes and prokaryotes, respectively, only non-membrane organelles can be found. Mitochondria, plastids, the Golgi complex and vacuoles are membrane organelles, which means they are not suitable as answers. The cell center is found only in eukaryotes. Ribosomes are found in both prokaryotes and eukaryotes.
Answer: ribosomes.