Eukaryotic nucleus is enclosed by a double membrane called as the nuclear envelope.
Chloroplasts have outer and inner membrane separated by a intramembranous space of 10 to 20 nm.
Mitochondria too has inner and outer membrane. The inner membrane folds to form cristae.
Ribosomes are the translational apparatus of the cell with two major components the small ribosomal subunit which reads the RNA, and the large subunit which joins amino acids to form a polypeptide chain. Each subunit is composed of one or more rRNA molecules and a variety of proteins. It is devoid of any membrane.