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.
If you enter military service for more than 30 days, your employing office must give you a notice explaining that your enrollment may continue for up to 24 months and that you are responsible for the employee share of the premiums for the first 12 months and for 102 percent of the premium afterwards.