In addition to such jurisdiction as previously conferred upon them, municipal courts having a salaried judge or judges shall have original jurisdiction of all prosecutions and proceedings in behalf of the people of this state for all misdemeanors and offenses arising under the laws of this state and committed within the corporate limits of the cities in which the courts are located, and which are punishable by a fine or imprisonment for not more than 1 year, or both, and may issue all lawful writs and process and do all lawful acts which may be necessary and proper to carry into effect the jurisdiction given by this act. This act shall not affect the jurisdiction of the circuit court over any case pending in the circuit court when this 1974 amendatory act takes effect.