Question

The earliest cells were prokaryotes, surrounded by a cell membrane but lacking which key structure?

Answer 1

nucleus

The first organisms were made of only one cell   Figure below  . The earliest cells were prokaryotes . Prokaryotic cells are surrounded by a cell membrane. They do not have a nucleus. Their organelles are free in the cell. The cells get their nutrients directly from the water they live in. The cells need to use these nutrients to live and grow.