There shall be a city planning commission consisting of five members, four of whom shall be citizens who hold no other city office or employment, selected by the council one each year for overlapping terms of four years, and one of whom shall be a member of the council, designated annually by the council. The commission shall adopt its own rules, and elect its own officers annually. It shall have all the power and authority conferred upon city planning commissions by state law and such other duties as may be imposed upon it by the administrative code. Its members shall serve without compensation.