A new approach is employed to provide the required expressions for the bare constituent quark densities in the proton. In this approach, we assume the bare quark densities take a Gaussian form in four-momentum space, which fulfill more properly the desired constrains of parton densities inside the proton. Using the modified chiral quark model and the related convolutions, the parton densities inside the proton are obtained. By evolving the gluon density to high energy scale, the contribution of charm quark to the proton structure function can be extracted and it is found in good agreement with the available experimental data. Sea quark ((anti-)strange) densities are calculated and compared with the ones from some phenomenological and experimental groups in which consistent results are obtained. What makes the results more valuable is that the initial framework is completely theoretical and we do not need to resort to any parametrizations in our calculations.