In most multicellular organisms, every cell carries the same DNA, but this genetic information is used in varying ways by different types of cells. In other words, what a cell does within an organism dictates which of its genes are expressed.
Most enlisted positions require four years of active duty. If you join the Navy through an officer program, you must serve at least four of your eight years on active duty. However, pilots and flight officers must serve a minimum of eight to 10 years of active duty. Dentists, Medical Service Corps officers and nurses must serve a minimum of three years of active duty.
appointed in the above categories to fill active force requirements must enter EAD before reaching age 35 years. Officers serving in NC or BSC must be able to complete 20 years active federal military service to include 10 years active federal commissioned service by the end of the month of the officer's 62nd birthday.