The present invention relates to an improved process for producing chemical cellulose pulp wherein biopolymers are added immediately before, during or after a bleaching step, depending on pulp characteristics and on process conditions used. The biopolymers according to the present invention are starches chemically modified by an etherification reaction. This treatment results in a differentiated pulp having improved physical, chemical and mechanical properties when compared with cellulose pulps obtained by traditional processes. The use of said biopolymer alters the relations between important pulp properties rendering their application in papermaking process advantageous. This differentiation increases the possibilities of use and also of new applications, including for the substitution of pulps produced from other cellulose sources. Thus, the present invention also relates to methods of making paper, such as printing, writing, decorative, special or tissue-type papers, through the use of the cellulose pulps modified by the above process.