Bonds in the total amount of two billion eight hundred fifty million dollars ($2,850,000,000), exclusive of refunding bonds, or so much thereof as is necessary, are hereby authorized to be issued and sold for carrying out the purposes expressed in this part and to reimburse the General Obligation Bond Expense Revolving Fund pursuant to Section 16724.5 of the Government Code. All bonds herein authorized which have been duly sold and delivered as provided herein shall constitute valid and legally binding general obligations of the state, and the full faith and credit of the state is hereby pledged for the punctual payment of both principal and interest thereof.