Bacteria are prokaryotic organisms. Being prokaryotes, bacteria do not have a nucleus in their cells. Their DNA or the genetic material lies in the cytoplasm itself. Therefore, if the observed cells have a nucleus and other membrane-bound organelles, this means that those cells were not the bacterial cells. Bacterial cells also do not have other membrane-bound organelles such as mitochondria, endoplasmic reticulum, etc.
Proteins in the cell membrane provide the structural support aspect. There are also channel proteins in the cell membrane that help substances pass through the cell membrane.
