Always start with something small. Bacteria are single-celled organisms that have the necessary requirements for bing regarded as living organisms. They have DNA which is required for genetic engineering. Even with bacteria being small, the DNA genome is still a very large unit to try to manipulate. The next thing is, once you have performed the genetic engineering, placing the genetic sequence in the bacteriums DNA, a new cell has to be grown from the original cell. This is not a problem with bacteria, as they reproduce using a process known as binary fission. Bacteria are also expendable. Cultures of bacteria may be cultivated using appropriate incubation procedures and media. It is possible to secure a wide range of acceptable bacteria to work with at a relatively low expense. It is always important to control expenses in projects such as genetic engineering, where time and money are always controlling factors that dictate the possibility of success.