The Planning Commission may adopt the Master Plan as a whole by a single resolution or may, by successive resolutions, adopt successive parts of the Plan, such parts corresponding with major geographical sections or divisions of the Municipality or with functional subdivisions of the subject matter of the Plan. In addition, the Commission may adopt any amendment or extension of the Plan or an addition thereto. Before the adoption of the Plan or any such part, amendment, extension or addition, the Commission shall hold at least one public hearing thereon, notice of the time and place of which shall be given, not less than fifteen days prior to such hearing, by one publication in a newspaper of general circulation in the Municipality and by registered United States mail to each public utility company and to each railroad company owning or operating any public utility or railroad within the geographical sections or divisions of the Municipality affected. The adoption of the Plan or of any such part of amendment or extension or addition shall be by resolution of the Commission carried by the affirmative votes of not less than six members of the Commission. The resolution shall refer expressly to the maps and descriptive and other matter intended by the Commission to form the whole or part of the Plan, and the action taken shall be recorded on the map and Plan and descriptive matter by the identifying signature of the Chairman and/or Secretary of the Commission. An attested copy of the Plan or part thereof shall be certified to Council and to the County Register of Deeds. An attested copy of the Plan or parts thereof shall be certified to Council.