Also visible in the amoeba is the nucleus, which contains the amoeba's DNA. In order to reproduce the ameba goes through mitotic division, where the nucleus duplicates its genetic material and the cytoplasm splits into two new daughter cells, each identical to the original parent. This method of reproduction is called binary fission. Another structure easily seen in the amoeba is the contractile vacuole. This organelle pumps out excess water so that the amoeba does not burst or lyse.