All members of the commission appointed by the governor shall be appointed for terms of four years, with staggered expiration dates. The terms of office of members appointed by the governor shall commence and end as provided by section 69.19. Legislative members of the commission shall serve terms of office as provided in section 69.16B. A vacancy on the commission shall be filled for the unexpired term of the vacancy in the same manner as the original appointment was made. If a legislative member ceases to be a member of the general assembly the legislative member may continue to serve until a successor is appointed.