Actually, organelle replication , occurs during the G2 stage of the cell cycle . During this stage, organelles are replicated and proteins are synthesized. The G2 phase follows DNA replication which occurs during the S-phase. The actual cell cycle begins with the resting phase called G0, followed by the G1 phase, the S and G2 phases which are known as interphase. The M or mitosis phase is when the cell divides into two daughter cells. During G0, cells are at "rest" and during interphase--G1, cells grow and synthesize the 20 amino acids needed to manufacture proteins later on. During S phase, DNA synthesis occurs. During G2, production of microtubules occurs and other organelles are manufactured. During M phase, mitosis occurs and when the two daughter cells are produced, they enter the G0 step once again.
Prokaryotic cells have a structure that is less complex than eukaryotic cells. They do not have a nucleus or region where the DNA is bound by a membrane. Prokaryotic DNA is coiled up in a region of the cytoplasm called the nucleoid. Like eukaryotic cells, prokaryotic cells contain a plasma membrane, cell wall, and cytoplasm. Unlike eukaryotic cells, prokaryotic cells do not contain membrane-bound organelles. However, they do contain some non-membranous organelles such as ribosomes, flagella, and plasmids (circular DNA structures that are not involved in reproduction). Examples of prokaryotic cells include bacteria and archaeans .