A City Planning Commission to be composed of seven members, appointed as provided by law (53 P.S. § 10202), is hereby created in and for the City. The Planning Commission shall perform all duties and may exercise all powers conferred by law upon City planning agencies; provided, the Planning Commission previously created in and for the said City shall constitute the tenure of any of the members thereof, but any and all vacancies in the said Commission, hereafter occurring, shall be filled in the manner and for the term provided in the law governing City planning commissions in effect at the time of the happening of said vacancy.