Final answer:
The first 'living' cells in the Archean had crucial components such as a plasma membrane, cytoplasm, ribosomes, and DNA. These fundamental structures are found in prokaryotic cells, which include Bacteria and Archaea, with the latter group possibly being the ancestors of eukaryotic cells.
Step-by-step explanation:
The first "living" cells to appear in the Archean contained key components that are essential to life. Given the evidence, scientists believe that these early cells were prokaryotes, specifically belonging to the domains of Bacteria and Archaea. The Archaea are particularly noteworthy because they include microbes that thrive under extreme conditions and may have been among the earliest forms of life.
The key components of these earliest cells included a plasma membrane that separated the cell from its environment, cytoplasm containing the jelly-like cytosol, ribosomes for protein synthesis, and genetic material in the form of DNA to store and transmit hereditary information.
Some Archaea are thought to have given rise to eukaryotic cells, as they share similarities in cell membrane and biochemistry. These prokaryotes were the sole inhabitants of Earth for billions of years before eukaryotes emerged, and they set the stage for the vast diversity of life we see today.