All cells need a membrane. The membrane helps with keeping in all the fluids and organelles plus it takes in and sends out important things. Plant cells and bacteria have cell walls which give an extra layer of protection.
Yes, the cells of archaebacteria, bacteria, protists, fungi, plants and animals all have cell membranes. (Viruses have protein coats, not cell membranes and thus are not true 'cells'.) Thus indeed,...