The chloroplast genome of higher plants is relatively small and simple. This genome contains about 120 genes which code for chloroplast proteins. The organelle’s genome also contains ribosomal RNA genes which code for the RNA components of the chloroplast ribosome. In this program, students identify the ribosomal RNA genes in the chloroplast genome of spinach. Students first isolate chloroplasts from fresh spinach and then prepare DNA from the isolated organelle. The DNA is digested with EcoR1, electrophoresed, and the separated fragments transferred to a nylon membrane. The DNA fragments containing the ribosomal genes are then detected by hybridization using a biotin-labeled probe made from a plasmid that contains the ribosomal gene sequences. Fresh spinach, microscopes, ethyl alcohol, a water bath incubator that will maintain a temperature of 60-65°C, and a centrifuge that can be operated at a force of at least 3000 x g are needed for the program. A microcentrifuge is also desirable, but not absolutely necessary.