(a) Appointed commission members serve staggered six-year terms. Every two years:
(1) the term of one of the members appointed under Section 1701.051(a)(1) expires;
(2) the term of one of the members appointed under Section 1701.051(a)(2) expires; and
(3) the term of one of the members appointed under Section 1701.051(a)(3) expires.
(b) A vacancy in an office of a member of the commission shall be filled for the unexpired term.